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Botha JA, Trueman CN, Kirkman SP, Arnould JPY, Lombard AT, Connan M, Hofmeyr GJG, Seakamela SM, Pistorius PA. Geographical, temporal, and individual-based differences in the trophic ecology of female Cape fur seals. Ecol Evol 2023; 13:e9790. [PMID: 36789339 PMCID: PMC9909003 DOI: 10.1002/ece3.9790] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 12/30/2022] [Accepted: 01/10/2023] [Indexed: 02/11/2023] Open
Abstract
Information on resource use and trophic dynamics of marine predators is important for understanding their role in ecosystem functioning and predicting population-level responses to environmental change. Where separate populations experience different local environmental conditions, geographic variability in their foraging ecology is often expected. Within populations, individuals also vary in morphology, physiology, and experience, resulting in specialization in resource use. In this context, isotopic compositions of incrementally grown tissues such as keratinous hairs offer a valuable opportunity to study long-term variation in resource and habitat use. We investigated the trophic ecology of female Cape fur seals (Arctocephalus pusillus pusillus) using carbon and nitrogen isotopic compositions of serially sampled whiskers collected at four breeding sites along the coast of South Africa. Drawing on over 900 isotopic measurements, we assessed geographic variability in isotopic niche width between colonies and the degree of individual specialization. We found slight, but clear geographic differences in isotopic ratios and isotopic niche widths, seemingly related to ecological setting, with niche widths being proportional to the area of available shelf and shelf-slope habitat surrounding the colony. We further identified periodic oscillations in isotopic ratios, which likely reflect temporal patterns in foraging distribution and prey type, linked to shifts in the availability of prey resources and their interaction with constraints on individual females throughout their breeding cycle. Finally, individual specialization indices revealed that each of the study populations contain specialist individuals that utilize only a small subset of the total population niche width. The degree of individual specialization was, however, not consistent across colonies and may reflect an interactive influence between density-dependent effects and habitat heterogeneity. Overall, this study provides important information on the trophic ecology of Cape fur seals breeding in South Africa and highlights the need to consider geographic and individual variability when assessing the foraging ecology of marine predators.
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Affiliation(s)
- Jonathan A. Botha
- Marine Apex Predator Research Unit (MAPRU), Department of Zoology and Institute for Coastal and Marine ResearchNelson Mandela UniversityGqeberhaSouth Africa
| | - Clive N. Trueman
- Ocean and Earth Science, SouthamptonUniversity of SouthamptonSouthamptonUK
| | - Stephen P. Kirkman
- Marine Apex Predator Research Unit (MAPRU), Department of Zoology and Institute for Coastal and Marine ResearchNelson Mandela UniversityGqeberhaSouth Africa
- Oceans and Coast Research, Department of ForestryFisheries and the EnvironmentCape TownSouth Africa
| | - John P. Y. Arnould
- Faculty of Science, Engineering and Built EnvironmentDeakin UniversityBurwoodVictoriaAustralia
| | - Amanda T. Lombard
- Marine Apex Predator Research Unit (MAPRU), Department of Zoology and Institute for Coastal and Marine ResearchNelson Mandela UniversityGqeberhaSouth Africa
| | - Maëlle Connan
- Marine Apex Predator Research Unit (MAPRU), Department of Zoology and Institute for Coastal and Marine ResearchNelson Mandela UniversityGqeberhaSouth Africa
| | - G. J. Greg Hofmeyr
- Marine Apex Predator Research Unit (MAPRU), Department of Zoology and Institute for Coastal and Marine ResearchNelson Mandela UniversityGqeberhaSouth Africa
- Port Elizabeth Museum at BayworldGqeberhaSouth Africa
| | - S. Mduduzi Seakamela
- Oceans and Coast Research, Department of ForestryFisheries and the EnvironmentCape TownSouth Africa
| | - Pierre A. Pistorius
- Marine Apex Predator Research Unit (MAPRU), Department of Zoology and Institute for Coastal and Marine ResearchNelson Mandela UniversityGqeberhaSouth Africa
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2
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Active breeding seabirds prospect alternative breeding colonies. Oecologia 2023; 201:341-354. [PMID: 36746795 DOI: 10.1007/s00442-023-05331-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Accepted: 01/30/2023] [Indexed: 02/08/2023]
Abstract
Compared to other animal movements, prospecting by adult individuals for a future breeding site is commonly overlooked. Prospecting influences the decision of where to breed and has consequences on fitness and lifetime reproductive success. By analysing movements of 31 satellite- and GPS-tracked gull and tern populations belonging to 14 species in Europe and North America, we examined the occurrence and factors explaining prospecting by actively breeding birds. Prospecting in active breeders occurred in 85.7% of studied species, across 61.3% of sampled populations. Prospecting was more common in populations with frequent inter-annual changes of breeding sites and among females. These results contradict theoretical models which predict that prospecting is expected to evolve in relatively predictable and stable environments. More long-term tracking studies are needed to identify factors affecting patterns of prospecting in different environments and understand the consequences of prospecting on fitness at the individual and population level.
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3
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Sage E, Bouten W, van Dijk W, Camphuysen KCJ, Shamoun-Baranes J. Built up areas in a wet landscape are stepping stones for soaring flight in a seabird. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 852:157879. [PMID: 35944643 DOI: 10.1016/j.scitotenv.2022.157879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 07/29/2022] [Accepted: 08/03/2022] [Indexed: 06/15/2023]
Abstract
The energy exchange between the Earth's surface and atmosphere results in a highly dynamic habitat through which birds move. Thermal uplift is an atmospheric feature which many birds are able to exploit in order to save energy in flight, but which is governed by complex surface-atmosphere interactions. In mosaic landscapes consisting of multiple land uses, the spatial distribution of thermal uplift is expected to be heterogenous and birds may use the landscape selectively to maximise flight over areas where thermal soaring opportunities are best. Flight generalists such as the lesser black-backed gull, Larus fuscus, are expected to be less reliant on thermal uplift than obligate soaring birds. Nevertheless, gulls may select flight behaviours and routes in response to or in anticipation of thermal uplift in order to reduce their transport costs, even in landscapes where thermal uplift isn't prevalent. We explore thermal soaring over land in lesser black-backed gulls by using high-resolution GPS tracking to characterise individual instances of thermal soaring and detailed energy exchange modelling to map the thermal landscape which gulls experience. We determine that lesser black-backed gulls are regularly able to undertake thermal soaring, even in a wet temperate landscape below sea level. By examining the relationship between lesser black-backed gull flight, thermal uplift and land use, we determine that built up areas, particularly towns and cities, provide thermal uplift hotspots which lesser black-backed gulls preferentially make use of, resulting in more opportunities for energy saving flight through thermal soaring.
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Affiliation(s)
- Elspeth Sage
- Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, P.O. Box 94240, 1090GE Amsterdam, the Netherlands.
| | - Willem Bouten
- Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, P.O. Box 94240, 1090GE Amsterdam, the Netherlands
| | - Walter van Dijk
- Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, P.O. Box 94240, 1090GE Amsterdam, the Netherlands
| | - Kees C J Camphuysen
- Royal Netherlands Institute for Sea Research (NIOZ), P.O. Box 59, 1790AB Den Burg, Texel, the Netherlands
| | - Judy Shamoun-Baranes
- Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, P.O. Box 94240, 1090GE Amsterdam, the Netherlands
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4
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Garthe S, Schwemmer P, Kubetzki U, Heinze B. Effects of agricultural practices on foraging habitats of a seabird species in the Baltic Sea. Ecol Evol 2022; 12:e9551. [PMID: 36440314 PMCID: PMC9682205 DOI: 10.1002/ece3.9551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Revised: 09/13/2022] [Accepted: 09/23/2022] [Indexed: 11/25/2022] Open
Abstract
Omnivorous and opportunistic species may be good indicators of food availability. Gulls often use human‐impacted landscapes and may respond to changes by altering their feeding ecology. We investigated the foraging behavior of individual common gulls (Larus canus), focusing on their distribution during foraging and their selected habitat types. We tracked adult common gulls using GPS telemetry at their largest breeding colony in the southwestern Baltic Sea, Germany. Foraging habitats were analyzed from tracking data for three breeding seasons 2016, 2017, and 2019 and were compared with potentially available foraging habitats. Most breeding birds flew toward terrestrial areas. Feeding sites were located on average 11.7–14.3 km from the colony (range 0.9–36.5 km). Corn and sugar beet fields were used significantly and extensively compared with their availability in 2016 and 2017, while wheat, rape, and barley fields were used significantly less. Data from 2019 suggested seasonal shifts in habitat use. Birds spent between 30 and 1300 min per week at their preferred feeding sites, with significant differences between the major habitats selected. We found a stable, clear, multiyear pattern in common gull foraging behavior in relation to agricultural practices. Fields with little or no crop cover and thus access to the soil were preferred over fields with high crop cover. These results suggest that local food availability may be limiting further population increases in this species.
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Affiliation(s)
- Stefan Garthe
- Research and Technology Centre (FTZ) Kiel University Büsum Germany
| | | | - Ulrike Kubetzki
- Research and Technology Centre (FTZ) Kiel University Büsum Germany
| | - Bernd Heinze
- Verein Langenwerder zum Schutz der Wat‐ und Wasservögel e.V. Nossendorf Germany
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5
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Sato T, Yabuhara Y, Okado J, Watanuki Y, Yamauchi A, Kawaguchi Y. At-Sea Habitat Use of Rhinoceros Auklets Breeding in the Shelf Region of Eastern Hokkaido. Zoolog Sci 2022; 39:261-269. [DOI: 10.2108/zs210014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2021] [Accepted: 12/16/2021] [Indexed: 11/17/2022]
Affiliation(s)
- Takahiro Sato
- Graduate School of Technology, Industrial, and Social Sciences, Tokushima University, 2-1 Minamijosanjima-cho, Tokushima 770-8506, Japan
| | - Yuki Yabuhara
- Graduate School of Technology, Industrial, and Social Sciences, Tokushima University, 2-1 Minamijosanjima-cho, Tokushima 770-8506, Japan
| | - Jumpei Okado
- Graduate School of Fisheries Sciences, Hokkaido University, 3-1-1 Minato-cho, Hakodate, Hokkaido 041-8611, Japan
| | - Yutaka Watanuki
- Graduate School of Fisheries Sciences, Hokkaido University, 3-1-1 Minato-cho, Hakodate, Hokkaido 041-8611, Japan
| | - Akihiro Yamauchi
- Graduate School of Technology, Industrial, and Social Sciences, Tokushima University, 2-1 Minamijosanjima-cho, Tokushima 770-8506, Japan
| | - Yoichi Kawaguchi
- Graduate School of Technology, Industrial, and Social Sciences, Tokushima University, 2-1 Minamijosanjima-cho, Tokushima 770-8506, Japan
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6
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Pereira JM, Ramos JA, Almeida N, Araújo PM, Ceia FR, Geraldes P, Marques AM, Matos DM, Rodrigues I, Dos Santos I, Paiva VH. Foraging costs drive within-colony spatial segregation in shearwaters from two contrasting environments in the North Atlantic Ocean. Oecologia 2022; 199:13-26. [PMID: 35044501 DOI: 10.1007/s00442-022-05109-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 12/07/2021] [Indexed: 11/24/2022]
Abstract
Foraging spatial segregation is frequent in central-place foragers during the breeding season, but very few studies have investigated foraging spatial segregation between adjacent sub-colonies. Here, we assessed for within-colony differences in the at-sea distribution, habitat use, trophic ecology and chick growth data of two Calonectris colonies differing in size, and breeding in two different environments in the North Atlantic Ocean. For this, we GPS tracked 52 Cory's shearwaters (Calonectris borealis) breeding in 2 small sub-colonies at Berlenga Island (Portugal) and 59 Cape Verde shearwaters (Calonectris edwardsii) breeding in 2 sub-colonies differing greatly in size at Raso Islet (Cabo Verde), over 2 consecutive breeding seasons (2017-2018), during chick-rearing. Cory's shearwaters from the two sub-colonies at Berlenga Island broadly overlapped in repeatedly used foraging patches close to the colony. In contrast, the foraging distribution of Cape Verde shearwaters was partially segregated in the colony surroundings, but overlapped at distant foraging areas off the west coast of Africa. Despite spatial segregation close to the colony, Cape Verde shearwaters from both sub-colonies departed in similar directions, foraged in similar habitats and exhibited mostly short trips within the archipelago of Cabo Verde. These results, corroborated with similar trophic ecology and chick growth rates between sub-colonies, support the idea that foraging spatial segregation in the colony surroundings was not likely driven by interference competition or directional bias. We suggest that high-quality prey patches are able to shape travel costs and foraging distribution of central-place foragers from neighbouring sub-colonies.
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Affiliation(s)
- Jorge M Pereira
- Department of Life Sciences, MARE-Marine and Environmental Sciences Centre, University of Coimbra, Calçada Martim de Freitas, 3000-456, Coimbra, Portugal. .,Environment and Sustainability Institute, University of Exeter, Penryn Campus, Penryn, Cornwall, TR10 9FE, UK.
| | - Jaime A Ramos
- Department of Life Sciences, MARE-Marine and Environmental Sciences Centre, University of Coimbra, Calçada Martim de Freitas, 3000-456, Coimbra, Portugal
| | - Nathalie Almeida
- Department of Life Sciences, MARE-Marine and Environmental Sciences Centre, University of Coimbra, Calçada Martim de Freitas, 3000-456, Coimbra, Portugal.,Biosfera Cabo Verde, Rua de Moçambique 28, Mindelo, Caixa Postal 233, São Vicente, Cabo Verde
| | - Pedro M Araújo
- Department of Life Sciences, MARE-Marine and Environmental Sciences Centre, University of Coimbra, Calçada Martim de Freitas, 3000-456, Coimbra, Portugal.,CIBIO/InBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, Campus Agrário de Vairão, Universidade do Porto, 4485-661, Vairão, Portugal
| | - Filipe R Ceia
- Department of Life Sciences, MARE-Marine and Environmental Sciences Centre, University of Coimbra, Calçada Martim de Freitas, 3000-456, Coimbra, Portugal
| | - Pedro Geraldes
- SPEA-Sociedade Portuguesa para o Estudo das Aves, Av. Columbano Bordalo Pinheiro, 87, 3º Andar, 1070-062, Lisbon, Portugal
| | - Ana M Marques
- Department of Life Sciences, MARE-Marine and Environmental Sciences Centre, University of Coimbra, Calçada Martim de Freitas, 3000-456, Coimbra, Portugal
| | - Diana M Matos
- Department of Life Sciences, MARE-Marine and Environmental Sciences Centre, University of Coimbra, Calçada Martim de Freitas, 3000-456, Coimbra, Portugal
| | - Isabel Rodrigues
- Department of Life Sciences, MARE-Marine and Environmental Sciences Centre, University of Coimbra, Calçada Martim de Freitas, 3000-456, Coimbra, Portugal.,Biosfera Cabo Verde, Rua de Moçambique 28, Mindelo, Caixa Postal 233, São Vicente, Cabo Verde
| | - Ivo Dos Santos
- Department of Life Sciences, MARE-Marine and Environmental Sciences Centre, University of Coimbra, Calçada Martim de Freitas, 3000-456, Coimbra, Portugal
| | - Vitor H Paiva
- Department of Life Sciences, MARE-Marine and Environmental Sciences Centre, University of Coimbra, Calçada Martim de Freitas, 3000-456, Coimbra, Portugal
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7
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Langley LP, Bearhop S, Burton NHK, Banks AN, Frayling T, Thaxter CB, Clewley GD, Scragg E, Votier SC. GPS tracking reveals landfill closures induce higher foraging effort and habitat switching in gulls. MOVEMENT ECOLOGY 2021; 9:56. [PMID: 34772460 PMCID: PMC8588598 DOI: 10.1186/s40462-021-00278-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 07/23/2021] [Indexed: 05/05/2023]
Abstract
BACKGROUND Landfills are a major subsidy for some animals, with implications for their life history and demography. Gulls feed extensively on food from landfills and closures are expected to have ecological consequences, but how this influences movement ecology is virtually unknown. METHODS We used GPS-tracking to quantify foraging behaviour and habitat choice of lesser black-backed gulls (Larus fuscus) breeding at two colonies before and after closure of two nearby landfills. RESULTS Following closure, gulls from both colonies travelled further and for longer to forage. Gulls also changed habitat selection, although this differed by colony - birds from one colony shifted to agricultural habitats, while at the other, increased their use of urban areas. These behavioural responses had no effect on adult body condition but hint at potential direct effects of higher foraging costs and indirect impacts by shifting to new habitats. CONCLUSIONS Our results demonstrate how landfill availability influences gull foraging movements and habitat selection. We also emphasize the value of biologging to detect rapid behavioural responses in contrast to more conventional demographic approaches, which is especially important for animals that spend the majority of their lives away from direct observation.
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Affiliation(s)
- Liam P Langley
- Centre for Ecology and Conservation, University of Exeter, Penryn, TR10 9EZ, UK.
| | - Stuart Bearhop
- Centre for Ecology and Conservation, University of Exeter, Penryn, TR10 9EZ, UK
| | - Niall H K Burton
- British Trust for Ornithology, The Nunnery, Thetford, IP24 2PU, UK
| | - Alex N Banks
- Natural England, Sterling House, Exeter, EX1 1QA, UK
| | - Tim Frayling
- Natural England, Sterling House, Exeter, EX1 1QA, UK
| | - Chris B Thaxter
- British Trust for Ornithology, The Nunnery, Thetford, IP24 2PU, UK
| | - Gary D Clewley
- British Trust for Ornithology, The Nunnery, Thetford, IP24 2PU, UK
| | - Emily Scragg
- British Trust for Ornithology, The Nunnery, Thetford, IP24 2PU, UK
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8
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Lourie E, Schiffner I, Toledo S, Nathan R. Memory and Conformity, but Not Competition, Explain Spatial Partitioning Between Two Neighboring Fruit Bat Colonies. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.732514] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Spatial partitioning between neighboring colonies is considered a widespread phenomenon in colonial species, reported mainly in marine birds. Partitioning is suspected to emerge due to various processes, such as competition, diet specialization, memory, information transfer, or even “foraging cultures.” Yet, empirical evidence from other taxa, and studies that tease apart the relative contribution of the processes underlying partitioning, remain scarce, mostly due to insufficiently detailed movement data. Here, we used high-resolution movement tracks (at 0.125 Hz) of 107 individuals belonging to two neighboring colonies of the Egyptian fruit bat (Rousettus aegyptiacus), a highly gregarious central-place forager, using the ATLAS reverse-GPS system in the Hula Valley, Israel. Based on comparisons between agent-based mechanistic models and observed spatial partitioning patterns, we found high levels of partitioning of both area and tree resources (<11% overlap) that were stable across different fruiting seasons. Importantly, partitioning could not have emerged if the bats’ movement was only limited by food availability and travel distances, as most commonly hypothesized. Rather than density-dependent or between-colony competition, memory, and, to a lesser extent, conformity in tree-use explain how partitioning develops. Elucidating the mechanisms that shape spatial partitioning among neighboring colonies in the wild under variable resource conditions is important for understanding the ecology and evolution of inter-group coexistence, space use patterns and sociality.
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9
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Silston B, Wise T, Qi S, Sui X, Dayan P, Mobbs D. Neural encoding of perceived patch value during competitive and hazardous virtual foraging. Nat Commun 2021; 12:5478. [PMID: 34531399 PMCID: PMC8446065 DOI: 10.1038/s41467-021-25816-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 08/26/2021] [Indexed: 11/16/2022] Open
Abstract
Natural observations suggest that in safe environments, organisms avoid competition to maximize gain, while in hazardous environments the most effective survival strategy is to congregate with competition to reduce the likelihood of predatory attack. We probed the extent to which survival decisions in humans follow these patterns, and examined the factors that determined individual-level decision-making. In a virtual foraging task containing changing levels of competition in safe and hazardous patches with virtual predators, we demonstrate that human participants inversely select competition avoidant and risk diluting strategies depending on perceived patch value (PPV), a computation dependent on reward, threat, and competition. We formulate a mathematically grounded quantification of PPV in social foraging environments and show using multivariate fMRI analyses that PPV is encoded by mid-cingulate cortex (MCC) and ventromedial prefrontal cortices (vMPFC), regions that integrate action and value signals. Together, these results suggest humans utilize and integrate multidimensional information to adaptively select patches highest in PPV, and that MCC and vMPFC play a role in adapting to both competitive and predatory threats in a virtual foraging setting. Humans adapt decision strategies in response to environmental demands. Here the authors show that decisions in a virtual foraging task can be modelled based on perceived patch value, which includes reward, competition and threat, and is associated with activity in ventromedial prefrontal and medial cingulate cortices.
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Affiliation(s)
- Brian Silston
- Columbia University, Department of Psychology, 406 Schermerhorn Hall 1190 Amsterdam Ave., New York, NY, 10027, USA
| | - Toby Wise
- Department of Humanities and Social Sciences and California Institute of Technology, 1200 E California Blvd, HSS 228-77, Pasadena, CA, 91125, USA.,Wellcome Centre for Human Neuroimaging, University College London, London, UK.,Max Planck UCL Centre for Computational Psychiatry and Ageing Research, University College London, London, UK
| | - Song Qi
- Department of Humanities and Social Sciences and California Institute of Technology, 1200 E California Blvd, HSS 228-77, Pasadena, CA, 91125, USA
| | - Xin Sui
- Department of Humanities and Social Sciences and California Institute of Technology, 1200 E California Blvd, HSS 228-77, Pasadena, CA, 91125, USA
| | - Peter Dayan
- Max Planck Institute for Biological Cybernetics, Tübingen, Germany.,University of Tübingen, Tübingen, Germany
| | - Dean Mobbs
- Department of Humanities and Social Sciences and California Institute of Technology, 1200 E California Blvd, HSS 228-77, Pasadena, CA, 91125, USA. .,Computation and Neural Systems Program at the California Institute of Technology, 1200 E California Blvd, HSS, 228-77, Pasadena, CA, USA.
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10
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Clatterbuck CA, Lewison RL, Orben RA, Ackerman JT, Torres LG, Suryan RM, Warzybok P, Jahncke J, Shaffer SA. Foraging in marine habitats increases mercury concentrations in a generalist seabird. CHEMOSPHERE 2021; 279:130470. [PMID: 34134398 DOI: 10.1016/j.chemosphere.2021.130470] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 02/28/2021] [Accepted: 03/30/2021] [Indexed: 06/12/2023]
Abstract
Methylmercury concentrations vary widely across geographic space and among habitat types, with marine and aquatic-feeding organisms typically exhibiting higher mercury concentrations than terrestrial-feeding organisms. However, there are few model organisms to directly compare mercury concentrations as a result of foraging in marine, estuarine, or terrestrial food webs. The ecological impacts of differential foraging may be especially important for generalist species that exhibit high plasticity in foraging habitats, locations, or diet. Here, we investigate whether foraging habitat, sex, or fidelity to a foraging area impact blood mercury concentrations in western gulls (Larus occidentalis) from three colonies on the US west coast. Cluster analyses showed that nearly 70% of western gulls foraged primarily in ocean or coastal habitats, whereas the remaining gulls foraged in terrestrial and freshwater habitats. Gulls that foraged in ocean or coastal habitats for half or more of their foraging locations had 55% higher mercury concentrations than gulls that forage in freshwater and terrestrial habitats. Ocean-foraging gulls also had lower fidelity to a specific foraging area than freshwater and terrestrial-foraging gulls, but fidelity and sex were unrelated to gull blood mercury concentrations in all models. These findings support existing research that has described elevated mercury levels in species using aquatic habitats. Our analyses also demonstrate that gulls can be used to detect differences in contaminant exposure over broad geographic scales and across coarse habitat types, a factor that may influence gull health and persistence of other populations that forage across the land-sea gradient.
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Affiliation(s)
| | | | - Rachael A Orben
- Oregon State University, Department of Fisheries and Wildlife, Hatfield Marine Science Center, Newport, OR, USA
| | - Joshua T Ackerman
- U.S. Geological Survey, Western Ecological Research Center, Dixon Field Station, Dixon, CA, USA
| | - Leigh G Torres
- Oregon State University, Department of Fisheries and Wildlife, Marine Mammal Institute, Hatfield Marine Science Center, Newport, OR, USA
| | - Robert M Suryan
- Oregon State University, Department of Fisheries and Wildlife, Hatfield Marine Science Center, Newport, OR, USA
| | | | | | - Scott A Shaffer
- San José State University, Department of Biological Sciences, San Jose, CA, USA
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11
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Aarts G, Mul E, Fieberg J, Brasseur S, van Gils JA, Matthiopoulos J, Riotte-Lambert L. Individual-Level Memory Is Sufficient to Create Spatial Segregation among Neighboring Colonies of Central Place Foragers. Am Nat 2021; 198:E37-E52. [PMID: 34260868 DOI: 10.1086/715014] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
AbstractCentral place foragers often segregate in space, even without signs of direct agonistic interactions. Using parsimonious individual-based simulations, we show that for species with spatial cognitive abilities, individual-level memory of resource availability can be sufficient to cause spatial segregation in the foraging ranges of colonial animals. The shapes of the foraging distributions are governed by commuting costs, the emerging distribution of depleted resources, and the fidelity of foragers to their colonies. When colony fidelity is weak and foragers can easily switch to colonies located closer to favorable foraging grounds, this leads to space partitioning with equidistant borders between neighboring colonies. In contrast, when colony fidelity is strong-for example, because larger colonies provide safety in numbers or individuals are unable to leave-it can create a regional imbalance between resource requirements and resource availability. This leads to nontrivial space-use patterns that propagate through the landscape. Interestingly, while better spatial memory creates more defined boundaries between neighboring colonies, it can lower the average intake rate of the population, suggesting a potential trade-off between an individual's attempt for increased intake and population growth rates.
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12
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Sebastiano M, Jouanneau W, Blévin P, Angelier F, Parenteau C, Gernigon J, Lemesle JC, Robin F, Pardon P, Budzinski H, Labadie P, Chastel O. High levels of fluoroalkyl substances and potential disruption of thyroid hormones in three gull species from South Western France. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 765:144611. [PMID: 33385816 DOI: 10.1016/j.scitotenv.2020.144611] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 12/08/2020] [Accepted: 12/16/2020] [Indexed: 06/12/2023]
Abstract
Per- and poly-fluoroalkyl substances (PFAS) raised increasing concerns over the past years due to their persistence and global distribution. Understanding their occurrence in the environment and their disruptive effect on the physiology of humans and wildlife remains a major challenge in ecotoxicological studies. Here, we investigate the occurrence of several carboxylic and sulfonic PFAS in 105 individuals of three seabird species (27 great black-backed gull Larus marinus; 44 lesser black-backed gull Larus fuscus graellsii; and 34 European herring gull Larus argentatus) from South western France. We further estimated the relationship between plasma concentrations of PFAS and i) the body condition of the birds and ii) plasma concentrations of thyroid hormone triiodothyronine (TT3). We found that great and lesser black-backed gulls from South Western France are exposed to PFAS levels comparable to highly contaminated species from other geographical areas, although major emission sources (i.e. related to industrial activities) are absent in the region. We additionally found that PFAS are negatively associated with the body condition of the birds in two of the studied species, and that these results are sex-dependent. Finally, we found positive associations between exposure to PFAS and TT3 in the great black-backed gull, suggesting a potential disrupting mechanism of PFAS exposure. Although only three years of data have been collected, we investigated PFAS trend over the study period, and found that great black-backed gulls document an increasing trend of plasma PFAS concentration from 2016 to 2018. Because PFAS might have detrimental effects on birds, French seabird populations should be monitored since an increase of PFAS exposure may impact on population viability both in the short- and long-term.
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Affiliation(s)
- M Sebastiano
- Centre d'Etudes Biologiques de Chizé (CEBC), UMR 7372 CNRS-Univ. La Rochelle, France.
| | - W Jouanneau
- Centre d'Etudes Biologiques de Chizé (CEBC), UMR 7372 CNRS-Univ. La Rochelle, France
| | - P Blévin
- Centre d'Etudes Biologiques de Chizé (CEBC), UMR 7372 CNRS-Univ. La Rochelle, France; Akvaplan-niva AS, Fram Centre, NO-9296 Tromsø, Norway
| | - F Angelier
- Centre d'Etudes Biologiques de Chizé (CEBC), UMR 7372 CNRS-Univ. La Rochelle, France
| | - C Parenteau
- Centre d'Etudes Biologiques de Chizé (CEBC), UMR 7372 CNRS-Univ. La Rochelle, France
| | - J Gernigon
- Réserve Naturelle de Lilleau des Niges, 17880, France
| | - J C Lemesle
- Réserve Naturelle de Lilleau des Niges, 17880, France
| | - F Robin
- Réserve Naturelle de Lilleau des Niges, 17880, France; Ligue pour la Protection des Oiseaux (LPO), 17300 Rochefort, France
| | - P Pardon
- Univ. Bordeaux, CNRS, EPOC, EPHE, UMR 5805, F-33600 Pessac, France
| | - H Budzinski
- Univ. Bordeaux, CNRS, EPOC, EPHE, UMR 5805, F-33600 Pessac, France
| | - P Labadie
- Univ. Bordeaux, CNRS, EPOC, EPHE, UMR 5805, F-33600 Pessac, France
| | - O Chastel
- Centre d'Etudes Biologiques de Chizé (CEBC), UMR 7372 CNRS-Univ. La Rochelle, France
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13
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Kavelaars MM, Baert JM, Stienen EWM, Shamoun-Baranes J, Lens L, Müller W. Breeding habitat loss reveals limited foraging flexibility and increases foraging effort in a colonial breeding seabird. MOVEMENT ECOLOGY 2020; 8:45. [PMID: 33292559 PMCID: PMC7653720 DOI: 10.1186/s40462-020-00231-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 10/26/2020] [Indexed: 05/21/2023]
Abstract
BACKGROUND Habitat loss can force animals to relocate to new areas, where they would need to adjust to an unfamiliar resource landscape and find new breeding sites. Relocation may be costly and could compromise reproduction. METHODS Here, we explored how the Lesser black-backed gull (Larus fuscus), a colonial breeding seabird species with a wide ecological niche, responds to the loss of its breeding habitat. We investigated how individuals adjusted their foraging behaviour after relocating to another colony due to breeding site destruction, and whether there were any reproductive consequences in the first years after relocation. To this end, we compared offspring growth between resident individuals and individuals that recently relocated to the same colony due to breeding habitat loss. Using GPS-tracking, we further investigated the foraging behaviour of resident individuals in both colonies, as well as that of relocated individuals, as enhanced foraging effort could represent a potential driver of reproductive costs. RESULTS We found negative consequences of relocation for offspring development, which were apparent when brood demand was experimentally increased. Recently relocated gulls travelled further distances for foraging than residents, as they often visited more distant foraging sites used by residents breeding in their natal colony as well as new areas outside the home range of the residents in the colony where they settled. CONCLUSIONS Our results imply that relocated individuals did not yet optimally adapt to the new food landscape, which was unexpected, given the social information on foraging locations that may have been available from resident neighbours in their new breeding colony. Even though the short-term reproductive costs were comparatively low, we show that generalist species, such as the Lesser black-backed gull, may be more vulnerable to habitat loss than expected. Long term studies are needed to investigate how long individuals are affected by their relocation in order to better assess potential population effects of (breeding) habitat loss.
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Affiliation(s)
- Marwa M Kavelaars
- Behavioural Ecology and Ecophysiology (BECO) Researchgroup, University of Antwerp, Universiteitsplein 1, 2610, Antwerp, Belgium.
- Terrestrial Ecology Unit (TEREC), Ghent University, K.L. Ledeganckstraat 35, 9000, Ghent, Belgium.
| | - Jan M Baert
- Behavioural Ecology and Ecophysiology (BECO) Researchgroup, University of Antwerp, Universiteitsplein 1, 2610, Antwerp, Belgium
- Terrestrial Ecology Unit (TEREC), Ghent University, K.L. Ledeganckstraat 35, 9000, Ghent, Belgium
| | - Eric W M Stienen
- Research Institute for Nature and Forest (INBO), Kliniekstraat 25, 1070, Brussels, Belgium
| | - Judy Shamoun-Baranes
- Computational Geo-Ecology, IBED, University of Amsterdam, P.O. Box 94248, 1090, GE, Amsterdam, The Netherlands
| | - Luc Lens
- Terrestrial Ecology Unit (TEREC), Ghent University, K.L. Ledeganckstraat 35, 9000, Ghent, Belgium
| | - Wendt Müller
- Behavioural Ecology and Ecophysiology (BECO) Researchgroup, University of Antwerp, Universiteitsplein 1, 2610, Antwerp, Belgium
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14
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Reusch K, Suárez N, Ryan PG, Pichegru L. Foraging movements of breeding Kelp Gulls in South Africa. MOVEMENT ECOLOGY 2020; 8:36. [PMID: 32905351 PMCID: PMC7469291 DOI: 10.1186/s40462-020-00221-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Accepted: 08/19/2020] [Indexed: 06/11/2023]
Abstract
BACKGROUND Kelp Gulls Larus dominicanus are one of the most abundant gulls in the Southern Hemisphere and can play an important role in their ecosystem. Understanding their foraging ecology is therefore important, especially in the context of anthropogenic changes of the environment. Over 35,000 Kelp Gulls breed in South Africa but little is known about their habitat use. It has been hypothesised that foraging mainly occurs in natural habitats while provisioning chicks to ensure high quality food, but knowledge on their foraging ecology during the incubation period remains poor. METHODS We tracked incubating Kelp Gulls from six colonies distributed along the coast of South Africa, varying in their distance to urban areas and landfills, and compared foraging trip patterns and habitat selection between colonies. RESULTS Gulls from west coast colonies, generally located further from landfills than the other studied colonies, travelled farther from their breeding sites (11.7 ± 9.9-17.8 ± 21.7 km, n = 3 colonies) than birds from Cape Town and south and east coast colonies (1.7 ± 0.8-3.1 ± 3.7 km, n = 3) with birds travelling farthest when foraging at sea. Gulls from all colonies spent more time foraging in marine, coastal, and natural terrestrial environments than scavenging in strongly modified habitats while incubating. CONCLUSIONS Our results suggest that Kelp Gulls in South Africa are able to exploit various resources from different foraging habitats, regardless of colony location and seem to rely less on anthropogenic habitats than expected.
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Affiliation(s)
- Katharina Reusch
- Institute for Coastal and Marine Research, Department of Zoology, Nelson Mandela University, PO Box 77000, Port Elizabeth, South Africa
| | - Nicolás Suárez
- Centro para el Estudio de Sistemas Marinos, CCT CENPAT-CONICET, Puerto Madryn, Chubut Argentina
| | - Peter G. Ryan
- FitzPatrick Institute of African Ornithology, DST-NRF Centre of Excellence, University of Cape Town, Rondebosch, Cape Town, 7701 South Africa
| | - Lorien Pichegru
- Institute for Coastal and Marine Research, Department of Zoology, Nelson Mandela University, PO Box 77000, Port Elizabeth, South Africa
- FitzPatrick Institute of African Ornithology, DST-NRF Centre of Excellence, University of Cape Town, Rondebosch, Cape Town, 7701 South Africa
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15
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Ausems ANMA, Skrzypek G, Wojczulanis-Jakubas K, Jakubas D. Sharing menus and kids' specials: Inter- and intraspecific differences in stable isotope niches between sympatrically breeding storm-petrels. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 728:138768. [PMID: 32339838 DOI: 10.1016/j.scitotenv.2020.138768] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 04/15/2020] [Accepted: 04/15/2020] [Indexed: 06/11/2023]
Abstract
Species sharing resources are predicted to compete, but co-occurring species can avoid competition through niche partitioning. Here, we investigated the inter- and intra-specific differences using stable isotope analyses in the black-bellied storm-petrel (Fregetta tropica) and the Wilson's storm-petrel (Oceanites oceanicus), breeding sympatrically in maritime Antarctica. We analysed stable carbon, nitrogen and oxygen isotopes in samples representing different life stages; chick down (pre-laying females), chick feather (chick), and adult blood (chick-rearing adults). Pre-laying females had wider stable isotope niches than chicks or chick-rearing adults, due to pre-laying females being free roaming while chick-rearing adults were central-place-foragers. Chicks were fed at a higher trophic level than the adults (higher δ15N), likely to compensate for the high nutritional demands of the growing chicks. Wilson's storm-petrels showed substantial overlap in stable isotope niches between all life stages, while the black-bellied storm-petrel chicks showed very little overlap. Wilson's storm-petrel niches significantly overlapped with those of pre-laying and chick-rearing black-bellied storm-petrels, suggesting negligible niche partitioning. Chick growth rate was negatively correlated with chick δ15N values, suggesting nutritional stress resulting in the use endogenous instead of dietary amino acids in protein synthesis. The higher trophic level of the relatively larger black-bellied storm-petrel chicks may be due to their longer stay in the nest, and relatively larger body mass gain, despite chick growth rates being similar to the smaller Wilson's storm-petrel chicks. Despite breeding sympatrically, the studied storm-petrel species showed considerable overlap in isotopic niches, which may be explained by sharing the same main prey species, reducing the detectability of foraging niche partitioning through stable isotope analyses. We found dietary shifts in black-bellied storm-petrels that are absent in Wilson's, showing different chick provisioning strategies, and shows that the high productivity of the Antarctic marine ecosystem may facilitate foraging niche overlap of sympatrically living species.
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Affiliation(s)
- Anne N M A Ausems
- The University of Gdańsk, Faculty of Biology, Department of Vertebrate Ecology and Zoology, ul. Wita Stwosza 59, 80-308 Gdańsk, Poland.
| | - Grzegorz Skrzypek
- The University of Western Australia, School of Biological Sciences, West Australian Biogeochemistry Centre, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - Katarzyna Wojczulanis-Jakubas
- The University of Gdańsk, Faculty of Biology, Department of Vertebrate Ecology and Zoology, ul. Wita Stwosza 59, 80-308 Gdańsk, Poland
| | - Dariusz Jakubas
- The University of Gdańsk, Faculty of Biology, Department of Vertebrate Ecology and Zoology, ul. Wita Stwosza 59, 80-308 Gdańsk, Poland
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16
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Ramírez F, Afán I, Bouten W, Carrasco JL, Forero MG, Navarro J. Humans shape the year-round distribution and habitat use of an opportunistic scavenger. Ecol Evol 2020; 10:4716-4725. [PMID: 32551055 PMCID: PMC7297764 DOI: 10.1002/ece3.6226] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 03/02/2020] [Accepted: 03/09/2020] [Indexed: 12/03/2022] Open
Abstract
Research focused on evaluating how human food subsidies influence the foraging ecology of scavenger species is scarce but essential for elucidating their role in shaping behavioral patterns, population dynamics, and potential impacts on ecosystems. We evaluate the potential role of humans in shaping the year-round distribution and habitat use of individuals from a typical scavenger species, the yellow-legged gull (Larus michahellis), breeding at southwestern Spain. To do this, we combined long-term, nearly continuous GPS-tracking data with spatially explicit information on habitat types and distribution of human facilities, as proxied by satellite imagery of artificial night lights. Overall, individuals were mainly associated with freshwater habitats (mean proportion, 95% CI: 40.6%, 36.9%-44.4%) followed by the marine-related systems (40.3, 37.7%-42.8%), human-related habitats (13.5%, 13.2%-13.8%), and terrestrial systems (5.5%, 4.6%-6.5%). However, these relative contributions to the overall habitat usage largely changed throughout the annual cycle as a likely response to ecological/physiological constraints imposed by varying energy budgets and environmental constraints resulting from fluctuations in the availability of food resources. Moreover, the tight overlap between the year-round spatial distribution of gulls and that of human facilities suggested that the different resources individuals relied on were likely of anthropogenic origin. We therefore provide evidence supporting the high dependence of this species on human-related food resources throughout the annual cycle. Owing to the ability of individuals to disperse and reach transboundary areas of Spain, Portugal, or Morocco, international joint efforts aimed at restricting the availability of human food resources would be required to manage this overabundant species and the associated consequences for biodiversity conservation (e.g., competitive exclusion of co-occurring species) and human interests (e.g., airports or disease transmission).
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Affiliation(s)
- Francisco Ramírez
- Departament de Biologia Evolutiva, Ecologia i Ciències AmbientalsFacultat de BiologiaUniversitat de BarcelonaBarcelonaSpain
| | - Isabel Afán
- Remote Sensing and GIS Laboratory (LAST‐EBD)Estación Biológica de Doñana CSICSevilleSpain
| | - Willem Bouten
- Theoretical and Computational EcologyInstitute for Biodiversity and Ecosystem DynamicsUniversity of AmsterdamAmsterdamThe Netherlands
| | - Josep Lluís Carrasco
- Departament de Fonaments Clínics, BioestadísticaFacultat de MedicinaUniversitat de BarcelonaBarcelonaSpain
| | | | - Joan Navarro
- Institut de Ciències del Mar - CSICBarcelonaSpain
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17
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Calderón-Capote MC, Dechmann DKN, Fahr J, Wikelski M, Kays R, O'Mara MT. Foraging movements are density-independent among straw-coloured fruit bats. ROYAL SOCIETY OPEN SCIENCE 2020; 7:200274. [PMID: 32537224 PMCID: PMC7277244 DOI: 10.1098/rsos.200274] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Accepted: 04/27/2020] [Indexed: 06/11/2023]
Abstract
Intraspecific competition in large aggregations of animals should generate density-dependent effects on foraging patterns. To test how large differences in colony size affect foraging movements, we tracked seasonal movements of the African straw-coloured fruit bat (Eidolon helvum) from four colonies that range from 4000 up to 10 million animals. Contrary to initial predictions, we found that mean distance flown per night (9-99 km), number of nightly foraging sites (2-3) and foraging and commuting times were largely independent of colony size. Bats showed classic central-place foraging and typically returned to the same day roost each night. However, roost switching was evident among individuals in three of the four colonies especially towards the onset of migration. The relatively consistent foraging patterns across seasons and colonies indicate that these bats seek out roosts close to highly productive landscapes. Once foraging effort starts to increase due to local resource depletion they migrate to landscapes with seasonally increasing resources. This minimizes high intraspecific competition and may help to explain why long-distance migration, otherwise rare in bats, evolved in this highly gregarious species.
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Affiliation(s)
- María C. Calderón-Capote
- Department of Migration, Max Planck Institute of Animal Behavior, Radolfzell, Germany
- Department of Biology, University of Munich, Munich, Germany
| | - Dina K. N. Dechmann
- Department of Migration, Max Planck Institute of Animal Behavior, Radolfzell, Germany
- Department of Biology, University of Konstanz, Konstanz, Germany
| | - Jakob Fahr
- Department of Migration, Max Planck Institute of Animal Behavior, Radolfzell, Germany
- TU Braunschweig, Zoological Institute, Braunschweig, Germany
| | - Martin Wikelski
- Department of Migration, Max Planck Institute of Animal Behavior, Radolfzell, Germany
- Department of Biology, University of Konstanz, Konstanz, Germany
| | - Roland Kays
- North Carolina Museum of Natural Sciences and Department of Forestry and Environmental Resources, North Carolina State University, Raleigh, NC, USA
| | - M. Teague O'Mara
- Department of Migration, Max Planck Institute of Animal Behavior, Radolfzell, Germany
- Department of Biology, University of Konstanz, Konstanz, Germany
- Department of Biological Sciences, Southeastern Louisiana University, Hammond, LA, USA
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18
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Zorrozua N, Egunez A, Aldalur A, Galarza A, Diaz B, Hidalgo J, Jover L, Sanpera C, Castège I, Arizaga J. Evaluating the effect of distance to different food subsidies on the trophic ecology of an opportunistic seabird species. J Zool (1987) 2020. [DOI: 10.1111/jzo.12759] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- N. Zorrozua
- Department of Ornithology Aranzadi Sciences Society Donostia Spain
| | - A. Egunez
- Department of Ornithology Aranzadi Sciences Society Donostia Spain
| | - A. Aldalur
- Department of Ornithology Aranzadi Sciences Society Donostia Spain
| | - A. Galarza
- Sustainable Development and Natural Environment Department County Council of Biscay Bilbao Spain
| | - B. Diaz
- Department of Ornithology Aranzadi Sciences Society Donostia Spain
| | - J. Hidalgo
- Sociedad Ornitológica Lanius Bilbao Spain
| | - L. Jover
- Institut de Recerca de la Biodiversitat (IRBio) Universitat de Barcelona Barcelona Spain
| | - C. Sanpera
- Institut de Recerca de la Biodiversitat (IRBio) Universitat de Barcelona Barcelona Spain
- Departament de Biologia Evolutiva Ecologia i Ciències Ambientals Facultat de Biologia Universitat de Barcelona Barcelona Spain
| | - I. Castège
- Centre de la mer de Biarritz Plateau de l'Atalaye Biarritz France
| | - J. Arizaga
- Department of Ornithology Aranzadi Sciences Society Donostia Spain
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19
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Sotillo A, Baert JM, Müller W, Stienen EWM, Soares AMVM, Lens L. Time and energy costs of different foraging choices in an avian generalist species. MOVEMENT ECOLOGY 2019; 7:41. [PMID: 31908778 PMCID: PMC6937837 DOI: 10.1186/s40462-019-0188-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/19/2019] [Accepted: 12/18/2019] [Indexed: 06/10/2023]
Abstract
BACKGROUND Animals can obtain a higher foraging yield by optimizing energy expenditure or minimizing time costs. In this study, we assessed how individual variation in the relative use of marine and terrestrial foraging habitats relates to differences in the energy and time investments of an avian generalistic feeder (the Lesser Black-backed Gull, Larus fuscus), and how this changes during the course of the chick-rearing period. METHODS We analyzed 5 years of GPS tracking data collected at the colony of Zeebrugge (Belgium). Cost proxies for energy expenditure (overall dynamic body acceleration) and time costs (trip durations and time spent away from the colony), together with trip frequency, were analyzed against the relative use of the marine and terrestrial habitats. RESULTS The marine habitat was most often used by males and outside weekends, when fisheries are active. Marine trips implied higher energetic costs and lower time investments. As chicks became older, terrestrial trips became more prevalent, and trip frequency reached a peak towards 20 days after hatching of the first egg. Over a full chick rearing period, energy costs varied widely between individuals, but no trends were found across the marine foraging gradient. Conversely, a higher use of marine foraging implied lower overall amounts of time spent away from the colony. CONCLUSIONS Foraging habitat choice was related to overall time costs incurred by gulls, but not to energy costs. The effect of chick age on foraging habitat choice and effort may be driven by energy expenditure constraints on the amount of marine foraging that can be performed. If time is less constraining to them, Lesser Black-backed Gulls may meet the increasing chick demand for food by switching from high to low energy demanding foraging strategies.
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Affiliation(s)
- Alejandro Sotillo
- Department of Biology, Terrestrial Ecology Unit, Ghent University, K.L. Ledeganckstraat 35, 9000 Ghent, Belgium
- Department of Biology & CESAM - Centre for Environmental and Marine Studies, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal
| | - Jan M. Baert
- Department of Biology, Terrestrial Ecology Unit, Ghent University, K.L. Ledeganckstraat 35, 9000 Ghent, Belgium
- Department of Biology – Behavioural Ecology and Ecophysiology Group, University of Antwerp, Campus Drie Eiken, Universiteitsplein 1, 2610 Wilrijk, Antwerp Belgium
| | - Wendt Müller
- Department of Biology – Behavioural Ecology and Ecophysiology Group, University of Antwerp, Campus Drie Eiken, Universiteitsplein 1, 2610 Wilrijk, Antwerp Belgium
| | - Eric W. M. Stienen
- Research Institute for Nature and Forest (INBO), Herman Teirlinckgebouw, Havenlaan 88, 1000 Brussels, Belgium
| | - Amadeu M. V. M. Soares
- Department of Biology & CESAM - Centre for Environmental and Marine Studies, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal
| | - Luc Lens
- Department of Biology, Terrestrial Ecology Unit, Ghent University, K.L. Ledeganckstraat 35, 9000 Ghent, Belgium
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20
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Environmental Predictability as a Cause and Consequence of Animal Movement. Trends Ecol Evol 2019; 35:163-174. [PMID: 31699411 DOI: 10.1016/j.tree.2019.09.009] [Citation(s) in RCA: 89] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 09/10/2019] [Accepted: 09/18/2019] [Indexed: 11/22/2022]
Abstract
The impacts of environmental predictability on the ecology and evolution of animal movement have been the subject of vigorous speculation for several decades. Recently, the swell of new biologging technologies has further stimulated their investigation. This advancing research frontier, however, still lacks conceptual unification and has so far focused little on converse effects. Populations of moving animals have ubiquitous effects on processes such as nutrient cycling and seed dispersal and may therefore shape patterns of environmental predictability. Here, we synthesise the main strands of the literature on the feedbacks between environmental predictability and animal movement and discuss how they may react to anthropogenic disruption, leading to unexpected threats for wildlife and the environment.
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21
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Cockerham S, Lee B, Orben RA, Suryan RM, Torres LG, Warzybok P, Bradley R, Jahncke J, Young HS, Ouverney C, Shaffer SA. Microbial Ecology of the Western Gull (Larus occidentalis). MICROBIAL ECOLOGY 2019; 78:665-676. [PMID: 30891612 DOI: 10.1007/s00248-019-01352-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Accepted: 02/17/2019] [Indexed: 06/09/2023]
Abstract
Avian species host diverse communities of microorganisms which have important roles in the life of birds, including increased metabolism, protection from disease, and immune system development. Along with high human populations and a diversity of human uses of coastal zones, anthropogenic food sources are becoming increasingly available to some species, including gulls. Anthropogenic associations increase the likelihood of encountering foreign or pathogenic bacteria. Diseases in birds caused by bacteria are a substantial source of avian mortality; therefore, it is essential to characterize the microbiome of seabirds. Here, we determined both core and environmentally derived microbial communities of breeding western gulls (Larus occidentalis) from six colonies in California and Oregon. Using DNA extracted from bacterial swabs of the bill, cloaca, and feet of gulls, 16S rRNA gene sequencing was performed targeting the V4 region. We identified a total of 8542 operational taxonomic units (OTUs) from 75 gulls. Sixty-eight OTUs were identified in gulls from all six colonies with the greatest representation from phyla's of Firmicutes, Proteobacteria, Bacteroidetes, and Actinobacteria. Overall, microbial richness based on Chao's Abundance-based Coverage Estimator (ACE) index was similar for all colonies (mean = 2347 OTUs) with the smallest coastal colonies having the highest richness (mean = 2626 OTUs) and the largest colonies, located farther off-shore, having the lowest (mean = 2068 OTUs). This survey represents the most in-depth assessment to date of microbes associated with western gulls, and the first study to identify both species-specific and environmentally derived bacteria across multiple populations.
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Affiliation(s)
- Susan Cockerham
- Department of Biological Sciences, San José State University, One Washington Square, San Jose, CA, 95192-0100, USA.
| | - Becky Lee
- Department of Biological Sciences, San José State University, One Washington Square, San Jose, CA, 95192-0100, USA
| | - Rachael A Orben
- Department of Fisheries and Wildlife, Hatfield Marine Science Center, Oregon State University, Newport, OR, 97365, USA
| | - Robert M Suryan
- Department of Fisheries and Wildlife, Hatfield Marine Science Center, Oregon State University, Newport, OR, 97365, USA
- Alaska Fisheries Science Center, Auke Bay Laboratories, NOAA Fisheries, 17109 Pt. Lena Loop Rd, Juneau, AK, 99801, USA
| | - Leigh G Torres
- Department of Fisheries and Wildlife, Marine Mammal Institute, Oregon State University, Hatfield Marine Science Center, Newport, OR, 97365, USA
| | - Pete Warzybok
- Point Blue Conservation Science, 2030 SE Marine Science Dr., Petaluma, CA, USA
| | - Russell Bradley
- Point Blue Conservation Science, 2030 SE Marine Science Dr., Petaluma, CA, USA
| | - Jaime Jahncke
- Point Blue Conservation Science, 2030 SE Marine Science Dr., Petaluma, CA, USA
| | - Hillary S Young
- Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, CA, USA
| | - Cleber Ouverney
- Department of Biological Sciences, San José State University, One Washington Square, San Jose, CA, 95192-0100, USA
| | - Scott A Shaffer
- Department of Biological Sciences, San José State University, One Washington Square, San Jose, CA, 95192-0100, USA
- Institute of Marine Sciences, University of California, Santa Cruz, CA, USA
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22
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Fuirst M, Veit RR, Hahn M, Dheilly N, Thorne LH. Effects of urbanization on the foraging ecology and microbiota of the generalist seabird Larus argentatus. PLoS One 2018; 13:e0209200. [PMID: 30562368 PMCID: PMC6298667 DOI: 10.1371/journal.pone.0209200] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Accepted: 12/01/2018] [Indexed: 01/22/2023] Open
Abstract
Larus gull species have proven adaptable to urbanization and due to their generalist feeding behaviors, they provide useful opportunities to study how urban environments impact foraging behavior and host-associated microbiota. We evaluated how urbanization influenced the foraging behavior and microbiome characteristics of breeding herring gulls (Larus argentatus) at three different colonies on the east coast of the United States. Study colonies represented high, medium and low degrees of urbanization, respectively. At all colonies, gulls frequently foraged at landfills and in other urban environments, but both the use of urban environments and gull foraging metrics differed with the degree of urbanization. Gulls at the more urban colonies used urban environments more frequently, showed higher rates of site fidelity and took shorter trips. Gulls at less urban colonies used a greater diversity of habitat types and foraged offshore. We observed high microbial diversity at all colonies, though microbial diversity was highest at the least urban colony where gulls used a wider variety of foraging habitats. This suggests that gulls may acquire a wider range of bacteria when visiting a higher variety of foraging sites. Our findings highlight the influence of urban habitats on gull movements and microbiome composition and diversity during the breeding season and represent the first application of amplicon sequence variants, an objective and repeatable method of bacterial classification, to study the microbiota of a seabird species.
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Affiliation(s)
- Matthew Fuirst
- School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, NY, United States of America
| | - Richard R. Veit
- Department of Biology, College of Staten Island (CSI) CUNY, Staten Island, NY, United States of America
| | - Megan Hahn
- School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, NY, United States of America
| | - Nolwenn Dheilly
- School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, NY, United States of America
| | - Lesley H. Thorne
- School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, NY, United States of America
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Enners L, Schwemmer P, Corman A, Voigt CC, Garthe S. Intercolony variations in movement patterns and foraging behaviors among herring gulls ( Larus argentatus) breeding in the eastern Wadden Sea. Ecol Evol 2018; 8:7529-7542. [PMID: 30151168 PMCID: PMC6106178 DOI: 10.1002/ece3.4167] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Revised: 03/29/2018] [Accepted: 04/13/2018] [Indexed: 11/28/2022] Open
Abstract
Herring gulls (Larus argentatus) are opportunistic predators that prefer to forage in the intertidal zone, but an increasing degree of terrestrial foraging has recently been observed. We therefore aimed to analyze the factors influencing foraging behavior and diet composition in the German Wadden Sea. Gulls from three breeding colonies on islands at different distances from the mainland were equipped with GPS data loggers during the incubation seasons in 2012-2015. Logger data were analyzed for 37 individuals, including 1,115 foraging trips. Herring gulls breeding on the island furthest from the mainland had shorter trips (mean total distance = 12.3 km; mean maximum distance = 4.2 km) and preferred to feed on the tidal flats close to the colony, mainly feeding on common cockles (Cerastoderma edule) and shore crabs (Carcinus maenas). In contrast, herring gulls breeding close to the mainland carried out trips with a mean total distance of 26.7 km (mean maximum distance = 9.2 km). These gulls fed on the neobiotic razor clams (Ensis leei) in the intertidal zone, and a larger proportion of time was spent in distant terrestrial habitats on the mainland, feeding on earthworms. δ13C and δ15N values were higher at the colony furthest from the mainland and confirmed a geographical gradient in foraging strategy. Analyses of logger data, pellets, and stable isotopes revealed that herring gulls preferred to forage in intertidal habitats close to the breeding colony, but shifted to terrestrial habitats on the mainland as the tide rose and during the daytime. Reduced prey availability in the vicinity of the breeding colony might force herring gulls to switch to feed on razor clams in the intertidal zone or to use distant terrestrial habitats. Herring gulls may thus act as an indicator for the state of the intertidal system close to their breeding colony.
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Affiliation(s)
- Leonie Enners
- Research and Technology Centre (FTZ)University of KielBüsumGermany
| | | | | | | | - Stefan Garthe
- Research and Technology Centre (FTZ)University of KielBüsumGermany
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24
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Corman AM, Schwemmer P, Mercker M, Asmus H, Rüdel H, Klein R, Boner M, Hofem S, Koschorreck J, Garthe S. Decreasing δ 13C and δ 15N values in four coastal species at different trophic levels indicate a fundamental food-web shift in the southern North and Baltic Seas between 1988 and 2016. ENVIRONMENTAL MONITORING AND ASSESSMENT 2018; 190:461. [PMID: 29998431 DOI: 10.1007/s10661-018-6827-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Accepted: 06/27/2018] [Indexed: 06/08/2023]
Abstract
Marine ecosystems are exposed to increasing human pressures and climatic change worldwide. It has therefore become essential to describe ecosystem statuses with respect to multinational protection schemes, often necessitating long-term monitoring programmes. Changes in the food-web structure, which can be monitored via stable isotope measurements, represent an important descriptor of the status of marine ecosystems. We investigated long-term changes (29 years) in isotopic values (δ13C and δ15N) in four indicative organisms at different trophic levels in the southern North and Baltic Seas: bladderwrack (Fucus vesiculosus), blue mussel (Mytilus ssp.), eelpout (Zoarces viviparus), and herring gull (Larus argentatus). Time series analyses using generalised additive models revealed largely consistent declines in δ13C and δ15N throughout all trophic levels of the coastal food web at all study sites, indicating a clear change in these coastal regions from 1988 to 2016. There were no clear long-term patterns in egg biometrics for herring gulls, except for a consistent increase in eggshell thickness. The declines in stable isotope values were in line with the results of previous long-term studies of single higher-trophic-level species, which suggested that the noted changes were mainly caused by altered foraging patterns of the studied species. The current results demonstrate that declines in δ13C and δ15N have occurred throughout the whole food web, not just in particular species. We discuss the possible reasons for the decrease in stable isotope values, including decreasing eutrophication and an increase in terrestrial carbon sources.
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Affiliation(s)
- Anna-Marie Corman
- Research & Technology Centre (FTZ), Kiel University, Hafentörn 1, 25761, Büsum, Germany
| | - Philipp Schwemmer
- Research & Technology Centre (FTZ), Kiel University, Hafentörn 1, 25761, Büsum, Germany.
| | - Moritz Mercker
- BIONUM Büro für Biostatistik, Finkenwerder Norderdeich 15 A, 21129, Hamburg, Germany
| | - Harald Asmus
- Alfred Wegener Institute, Hafenstraße 43, 25992, List/Sylt, Germany
| | - Heinz Rüdel
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Auf dem Aberg 1, 57392, Schmallenberg, Germany
| | - Roland Klein
- Insitute of Biogeography, University of Trier, Universitätsring 15, 54286, Trier, Germany
| | - Markus Boner
- Agroisolab GmbH, Prof.-Rehm-Str. 6, 52428, Jülich, Germany
| | - Sabine Hofem
- Agroisolab GmbH, Prof.-Rehm-Str. 6, 52428, Jülich, Germany
| | - Jan Koschorreck
- Federal Environmental Agency, Bismarckplatz 1, 14193, Berlin, Germany
| | - Stefan Garthe
- Research & Technology Centre (FTZ), Kiel University, Hafentörn 1, 25761, Büsum, Germany
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25
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Hedd A, Pollet IL, Mauck RA, Burke CM, Mallory ML, McFarlane Tranquilla LA, Montevecchi WA, Robertson GJ, Ronconi RA, Shutler D, Wilhelm SI, Burgess NM. Foraging areas, offshore habitat use, and colony overlap by incubating Leach's storm-petrels Oceanodroma leucorhoa in the Northwest Atlantic. PLoS One 2018; 13:e0194389. [PMID: 29742124 PMCID: PMC5942770 DOI: 10.1371/journal.pone.0194389] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Accepted: 03/02/2018] [Indexed: 11/19/2022] Open
Abstract
Despite their importance in marine food webs, much has yet to be learned about the spatial ecology of small seabirds. This includes the Leach’s storm-petrel Oceanodroma leucorhoa, a species that is declining throughout its Northwest Atlantic breeding range. In 2013 and 2014, we used global location sensors to track foraging movements of incubating storm-petrels from 7 eastern Canadian breeding colonies. We determined and compared the foraging trip and at-sea habitat characteristics, analysed spatial overlap among colonies, and determined whether colony foraging ranges intersected with offshore oil and gas operations. Individuals tracked during the incubation period made 4.0 ± 1.4 day foraging trips, travelling to highly pelagic waters over and beyond continental slopes which ranged, on average, 400 to 830 km from colonies. Cumulative travel distances ranged from ~900 to 2,100 km among colonies. While colony size did not influence foraging trip characteristics or the size of areas used at sea, foraging distances tended to be shorter for individuals breeding at the southern end of the range. Core areas did not overlap considerably among colonies, and individuals from all sites except Kent Island in the Bay of Fundy foraged over waters with median depths > 1,950 m and average chlorophyll a concentrations ≤ 0.6 mg/m3. Sea surface temperatures within colony core areas varied considerably (11–23°C), coincident with the birds’ use of cold waters of the Labrador Current or warmer waters of the Gulf Stream Current. Offshore oil and gas operations intersected with the foraging ranges of 5 of 7 colonies. Three of these, including Baccalieu Island, Newfoundland, which supports the species’ largest population, have experienced substantial declines in the last few decades. Future work should prioritize modelling efforts to incorporate information on relative predation risk at colonies, spatially explicit risks at-sea on the breeding and wintering grounds, effects of climate and marine ecosystem change, as well as lethal and sub-lethal effects of environmental contaminants, to better understand drivers of Leach’s storm-petrel populations trends in Atlantic Canada.
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Affiliation(s)
- April Hedd
- Psychology Department, Memorial University, St. John’s, NL, Canada
- * E-mail:
| | | | - Robert A. Mauck
- Biology Department, Kenyon College, Gambier, OH, United States of America
| | | | - Mark L. Mallory
- Department of Biology, Acadia University, Wolfville, NS, Canada
| | | | | | - Gregory J. Robertson
- Wildlife Research Division, Environment and Climate Change Canada, Mount Pearl, NL, Canada
| | | | - Dave Shutler
- Department of Biology, Acadia University, Wolfville, NS, Canada
| | - Sabina I. Wilhelm
- Canadian Wildlife Service, Environment and Climate Change Canada, Mount Pearl, NL, Canada
| | - Neil M. Burgess
- Ecotoxicology & Wildlife Health Division, Environment and Climate Change Canada, Mount Pearl, NL, Canada
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Genovart M, Bécares J, Igual JM, Martínez-Abraín A, Escandell R, Sánchez A, Rodríguez B, Arcos JM, Oro D. Differential adult survival at close seabird colonies: The importance of spatial foraging segregation and bycatch risk during the breeding season. GLOBAL CHANGE BIOLOGY 2018; 24:1279-1290. [PMID: 29178374 DOI: 10.1111/gcb.13997] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Revised: 10/20/2017] [Accepted: 11/07/2017] [Indexed: 05/10/2023]
Abstract
Marine megafauna, including seabirds, are critically affected by fisheries bycatch. However, bycatch risk may differ on temporal and spatial scales due to the uneven distribution and effort of fleets operating different fishing gear, and to focal species distribution and foraging behavior. Scopoli's shearwater Calonectris diomedea is a long-lived seabird that experiences high bycatch rates in longline fisheries and strong population-level impacts due to this type of anthropogenic mortality. Analyzing a long-term dataset on individual monitoring, we compared adult survival (by means of multi-event capture-recapture models) among three close predator-free Mediterranean colonies of the species. Unexpectedly for a long-lived organism, adult survival varied among colonies. We explored potential causes of this differential survival by (1) measuring egg volume as a proxy of food availability and parental condition; (2) building a specific longline bycatch risk map for the species; and (3) assessing the distribution patterns of breeding birds from the three study colonies via GPS tracking. Egg volume was very similar between colonies over time, suggesting that environmental variability related to habitat foraging suitability was not the main cause of differential survival. On the other hand, differences in foraging movements among individuals from the three colonies expose them to differential mortality risk, which likely influenced the observed differences in adult survival. The overlap of information obtained by the generation of specific bycatch risk maps, the quantification of population demographic parameters, and the foraging spatial analysis should inform managers about differential sensitivity to the anthropogenic impact at mesoscale level and guide decisions depending on the spatial configuration of local populations. The approach would apply and should be considered in any species where foraging distribution is colony-specific and mortality risk varies spatially.
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Affiliation(s)
- Meritxell Genovart
- IMEDEA (CSIC-UIB), Esporles, Mallorca, Spain
- CEAB (CSIC), Accés Cala Sant Francesc, Blanes,Girona, Catalonia, Spain
| | - Juan Bécares
- SEO/BirdLife - Marine Programme, Delegació de Catalunya, Barcelona, Spain
| | | | - Alejandro Martínez-Abraín
- Grupo de Investigación en Biología Evolutiva, Departamento de Bioloxía, Universidade da Coruña, A Coruña, Spain
| | - Raul Escandell
- SOM (Societat Ornitològica de Menorca), Es Castell, Menorca, Spain
| | - Antonio Sánchez
- Oficina Técnica Devesa-Albufera (Ayuntamiento de Valencia), Valencia, Spain
| | - Beneharo Rodríguez
- SEO/BirdLife - Marine Programme, Delegació de Catalunya, Barcelona, Spain
- Canary Islands' Ornithology and Natural History Group (GOHNIC), Tenerife, Canary Islands, Spain
| | - José M Arcos
- SEO/BirdLife - Marine Programme, Delegació de Catalunya, Barcelona, Spain
| | - Daniel Oro
- IMEDEA (CSIC-UIB), Esporles, Mallorca, Spain
- CEAB (CSIC), Accés Cala Sant Francesc, Blanes,Girona, Catalonia, Spain
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27
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Calizza E, Costantini ML, Careddu G, Rossi L. Effect of habitat degradation on competition, carrying capacity, and species assemblage stability. Ecol Evol 2017; 7:5784-5796. [PMID: 28811883 PMCID: PMC5552933 DOI: 10.1002/ece3.2977] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Revised: 03/03/2017] [Accepted: 03/07/2017] [Indexed: 11/11/2022] Open
Abstract
Changes in species’ trophic niches due to habitat degradation can affect intra‐ and interspecific competition, with implications for biodiversity persistence. Difficulties of measuring species’ interactions in the field limit our comprehension of competition outcomes along disturbance gradients. Thus, information on how habitat degradation can destabilize food webs is scarce, hindering predictions regarding responses of multispecies systems to environmental changes. Seagrass ecosystems are undergoing degradation. We address effects of Posidonia oceanica coverage reduction on the trophic organization of a macroinvertebrate community in the Tyrrhenian Sea (Italy), hypothesizing increased trophic generalism, niche overlap among species and thus competition and decreased community stability due to degraded conditions. Census data, isotopic analysis, and Bayesian mixing models were used to quantify the trophic niches of three abundant invertebrate species, and intra‐ and interspecific isotopic and resource‐use similarity across locations differing in seagrass coverage. This allowed the computation of (1) competition strength, with respect to each other and remaining less abundant species and (2) habitat carrying capacity. To explore effects of the spatial scale on the interactions, we considered both individual locations and the entire study area (“‘meadow scale”). We observed that community stability and habitat carrying capacity decreased as P. oceanica coverage declined, whereas niche width, similarity of resource use and interspecific competition strength between species increased. Competition was stronger, and stability lower, at the meadow scale than at the location scale. Indirect effects of competition and the spatial compartmentalization of species interactions increased stability. Results emphasized the importance of trophic niche modifications for understanding effects of habitat loss on biodiversity persistence. Calculation of competition coefficients based on isotopic distances is a promising tool for describing competitive interactions in real communities, potentially extendible to any subset of ecological niche axes for which specimens’ positions and pairwise distances can be obtained.
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Affiliation(s)
- Edoardo Calizza
- Department of Environmental Biology Sapienza University of Rome Rome Italy.,CoNISMa Rome Italy
| | | | - Giulio Careddu
- Department of Environmental Biology Sapienza University of Rome Rome Italy
| | - Loreto Rossi
- Department of Environmental Biology Sapienza University of Rome Rome Italy.,CoNISMa Rome Italy
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28
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Weiss O, Dorfman A, Ram T, Zadicario P, Eilam D. Rats do not eat alone in public: Food-deprived rats socialize rather than competing for baits. PLoS One 2017; 12:e0173302. [PMID: 28278246 PMCID: PMC5344391 DOI: 10.1371/journal.pone.0173302] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Accepted: 02/17/2017] [Indexed: 11/18/2022] Open
Abstract
Limited resources result in competition among social animals. Nevertheless, social animals also have innate preferences for cooperative behavior. In the present study, 12 dyads of food-deprived rats were tested in four successive trials, and then re-tested as eight triads of food-deprived rats that were unfamiliar to each other. We found that the food-deprived dyads or triads of rats did not compete for the food available to them at regular spatially-marked locations that they had previously learnt. Rather, these rats traveled together to collect the baits. One rat, or two rats in some triads, lead (ran ahead) to collect most of the baits, but "leaders" differed across trials so that, on average, each rat ultimately collected similar amounts of baits. Regardless of which rat collected the baits, the rats traveled together with no substantial difference among them in terms of their total activity. We suggest that rats, which are a social species that has been found to display reciprocity, have evolved to travel and forage together and to share limited resources. Consequently, they displayed a sort of 'peace economy' that on average resulted in equal access to the baits across trials. For social animals, this type of dynamics is more relaxed, tolerant, and effective in the management of conflicts. Rather than competing for the limited available food, the food-deprived rats socialized and coexisted peacefully.
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Affiliation(s)
- Omri Weiss
- Department of Zoology, Tel-Aviv University, Ramat Aviv, Israel
| | - Alex Dorfman
- Department of Zoology, Tel-Aviv University, Ramat Aviv, Israel
| | - Tamar Ram
- Department of Zoology, Tel-Aviv University, Ramat Aviv, Israel
| | - Pazit Zadicario
- Department of Zoology, Tel-Aviv University, Ramat Aviv, Israel
| | - David Eilam
- Department of Zoology, Tel-Aviv University, Ramat Aviv, Israel
- * E-mail:
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29
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Shaffer SA, Cockerham S, Warzybok P, Bradley RW, Jahncke J, Clatterbuck CA, Lucia M, Jelincic JA, Cassell AL, Kelsey EC, Adams J. Population-level plasticity in foraging behavior of western gulls ( Larus occidentalis). MOVEMENT ECOLOGY 2017; 5:27. [PMID: 29270295 PMCID: PMC5735870 DOI: 10.1186/s40462-017-0118-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Accepted: 11/28/2017] [Indexed: 05/05/2023]
Abstract
BACKGROUND Plasticity in foraging behavior among individuals, or across populations may reduce competition. As a generalist carnivore, western gulls (Larus occidentalis) consume a wide range of marine and terrestrial foods. However, the foraging patterns and habitat selection (ocean or land) of western gulls is not well understood, despite their ubiquity in coastal California. Here, we used GPS loggers to compare the foraging behavior and habitat use of western gulls breeding at two island colonies in central California. RESULTS Gulls from offshore Southeast Farallon Island (SFI; n = 41 gulls) conducted more oceanic trips (n = 90) of shorter duration (3.8 ± 3.3 SD hours) and distance (27.1 ± 20.3 km) than trips to the mainland (n = 41) which were nearly 4 times longer and 2 times farther away. In contrast, gulls from coastal Año Nuevo Island (ANI; n = 20 gulls) foraged at sites on land more frequently (n = 103) but trip durations (3.6 ± 2.4 h) and distances (20.8 ± 9.4 km) did not differ significantly from oceanic trips (n = 42) where trip durations were only slightly shorter (2.9 ± 2.7 h) and equidistant (20.6 ± 12.1 km). Gulls from both colonies visited more sites while foraging at sea but spent significantly longer (3-5 times) durations at each site visited on land. Foraging at sea was also more random compared to foraging trips over land where gulls from both colonies visited the same sites on multiple trips. The total home range of gulls from SFI (14,230 km2) was 4.5 times larger than that of gulls from ANI, consistent with greater resource competition resulting from a larger abundance of seabirds at SFI. CONCLUSIONS Population-level plasticity in foraging behavior was evident and dependent on habitat type. In addition, gulls from SFI were away foraging longer than gulls from ANI (22% vs. 7.5%, respectively), which impacts the defense of territories and attempts at nest predation by conspecifics. Our results can be used to explain lower chick productivity at SFI, and can provide insight into increased gull activity in urban areas.
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Affiliation(s)
- Scott A. Shaffer
- Department of Biological Sciences, San José State University, San Jose, CA 95192-0100 USA
- University of California, Institute of Marine Sciences, Santa Cruz, CA USA
| | - Sue Cockerham
- Department of Biological Sciences, San José State University, San Jose, CA 95192-0100 USA
| | | | | | | | - Corey A. Clatterbuck
- Department of Biological Sciences, San José State University, San Jose, CA 95192-0100 USA
- Biology Department, San Diego State University, San Diego, CA USA
| | - Magali Lucia
- University of California, Institute of Marine Sciences, Santa Cruz, CA USA
| | - Jennifer A. Jelincic
- Department of Biological Sciences, San José State University, San Jose, CA 95192-0100 USA
| | - Anne L. Cassell
- Department of Biological Sciences, San José State University, San Jose, CA 95192-0100 USA
| | - Emma C. Kelsey
- Department of Biological Sciences, San José State University, San Jose, CA 95192-0100 USA
- Western Ecological Research Center, U.S. Geological Survey, Santa Cruz Field Station, Santa Cruz, CA USA
| | - Josh Adams
- Western Ecological Research Center, U.S. Geological Survey, Santa Cruz Field Station, Santa Cruz, CA USA
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Terrestrial and Marine Foraging Strategies of an Opportunistic Seabird Species Breeding in the Wadden Sea. PLoS One 2016; 11:e0159630. [PMID: 27525661 PMCID: PMC4985156 DOI: 10.1371/journal.pone.0159630] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2015] [Accepted: 07/06/2016] [Indexed: 11/19/2022] Open
Abstract
Lesser black-backed gulls Larus fuscus are considered to be mainly pelagic. We assessed the importance of different landscape elements (open sea, tidal flats and inland) by comparing marine and terrestrial foraging behaviours in lesser black-backed gulls breeding along the coast of the southern North Sea. We attached GPS data loggers to eight incubating birds and collected information on diet and habitat use. The loggers recorded data for 10-19 days to allow flight-path reconstruction. Lesser black-backed gulls foraged in both offshore and inland areas, but rarely on tidal flats. Targets and directions were similar among all eight individuals. Foraging trips (n = 108) lasted 0.5-26.4 h (mean 8.7 h), and ranges varied from 3.0-79.9 km (mean 30.9 km). The total distance travelled per foraging trip ranged from 7.5-333.6 km (mean 97.9 km). Trips out to sea were significantly more variable in all parameters than inland trips. Presence in inland areas was closely associated with daylight, whereas trips to sea occurred at day and night, but mostly at night. The most common items in pellets were grass (48%), insects (38%), fish (28%), litter (26%) and earthworms (20%). There was a significant relationship between the carbon and nitrogen isotope signals in blood and the proportional time each individual spent foraging at sea/land. On land, gulls preferentially foraged on bare ground, with significantly higher use of potato fields and significantly less use of grassland. The flight patterns of lesser black-backed gulls at sea overlapped with fishing-vessel distribution, including small beam trawlers fishing for shrimps in coastal waters close to the colony and large beam-trawlers fishing for flatfish at greater distances. Our data show that individuals made intensive use of the anthropogenic landscape and seascape, indicating that lesser black-backed gulls are not a predominantly marine species during the incubation period.
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Isaksson N, Evans TJ, Shamoun-Baranes J, Åkesson S. Land or sea? Foraging area choice during breeding by an omnivorous gull. MOVEMENT ECOLOGY 2016; 4:11. [PMID: 27186375 PMCID: PMC4868019 DOI: 10.1186/s40462-016-0078-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Accepted: 04/04/2016] [Indexed: 05/05/2023]
Abstract
BACKGROUND Generalist predators may vary their diet and use of habitat according to both internal state (e.g. breeding stage) and external (e.g. weather) factors. Lesser black-backed gulls Larus fuscus (Linnaeus 1758) are dietary generalists, foraging in both terrestrial and marine habitats during breeding. We investigate what affects the gulls' propensity to forage at sea or on land. We assess the importance of terrestrial foraging to gulls in the Baltic Sea (sub. sp. L. f. fuscus), looking especially at their use of agricultural fields. RESULTS Through the GPS tracking of 19 individuals across 3 years we tracked 1038 foraging trips and found that 21.2 % of foraging trips were predominantly terrestrial, 9.0 % were a mix of terrestrial and marine, and 68.5 % were exclusively marine. Terrestrial trips were (1) more frequent when departing around sunrise, whereas marine trips occurred throughout the day. Additionally, trips with mostly land-based foraging decreased as the breeding season progressed, suggesting dietary switching coincident with the onset of chick provisioning. (2) During cloudy and cold conditions terrestrial foraging trips were more likely. (3) We found no differences between sexes in their land-based foraging strategy. (4) Gull individuals showed great variation in foraging strategy. Using observations of agricultural fields, carried out for one year, we found that (5) gulls preferentially foraged on fields with short vegetation, and there was a positive association with occurrence of waders and other species of gulls. (6) The availability and use of these preferred fields decreased through the breeding period. CONCLUSIONS This study found high prevalence of terrestrial foraging during early breeding as well as support for dietary switching early in the breeding season. The overall tendency for marine or terrestrial foraging was consistent within individuals, with gull identity accounting for much of the variation observed in foraging trips. Our results suggest that anthropogenic terrestrial food sources may play a role in the low breeding success of these gulls through either variation in quantity and/or quality. Finally, our study demonstrates the potential of combining data from GPS-tracking of individual animals with the 'ground-truthing' of habitat visited to elucidate the otherwise nebulous behavior of a generalist predator.
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Affiliation(s)
- Natalie Isaksson
- />Centre for Animal Movement Research, Department of Biology, Ecology Building, Lund University, Lund, SE-223 62 Sweden
| | - Thomas J. Evans
- />Centre for Animal Movement Research, Department of Biology, Ecology Building, Lund University, Lund, SE-223 62 Sweden
| | - Judy Shamoun-Baranes
- />Computational Geo-Ecology, University of Amsterdam, Postbus 94248, Amsterdam, 1090 GE The Netherlands
| | - Susanne Åkesson
- />Centre for Animal Movement Research, Department of Biology, Ecology Building, Lund University, Lund, SE-223 62 Sweden
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