1
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An unexpected presence in urban environment: factors governing occurrence of the vulnerable European turtle-dove (Streptopelia turtur) in the city of Rabat, Morocco. Urban Ecosyst 2022. [DOI: 10.1007/s11252-022-01234-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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2
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Benharzallah N, Bachir AS, Barbraud C. Nest characteristics and food supply affect reproductive output of white storks Ciconia ciconia in semi-arid areas. Biologia (Bratisl) 2022. [DOI: 10.1007/s11756-022-01011-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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3
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Ryeland J, House CM, Umbers KDL, Spencer RJ. Optimal clutch size and male incubation investment in the male-only incubating emu (Dromaius novaehollandiae). Behav Ecol Sociobiol 2021. [DOI: 10.1007/s00265-021-03110-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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4
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Nägeli M, Scherler P, Witczak S, Catitti B, Aebischer A, van Bergen V, Kormann U, Grüebler MU. Weather and food availability additively affect reproductive output in an expanding raptor population. Oecologia 2021; 198:125-138. [PMID: 34797425 PMCID: PMC8803806 DOI: 10.1007/s00442-021-05076-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Accepted: 11/01/2021] [Indexed: 11/24/2022]
Abstract
The joint effects of interacting environmental factors on key demographic parameters can exacerbate or mitigate the separate factors’ effects on population dynamics. Given ongoing changes in climate and land use, assessing interactions between weather and food availability on reproductive performance is crucial to understand and forecast population dynamics. By conducting a feeding experiment in 4 years with different weather conditions, we were able to disentangle the effects of weather, food availability and their interactions on reproductive parameters in an expanding population of the red kite (Milvus milvus), a conservation-relevant raptor known to be supported by anthropogenic feeding. Brood loss occurred mainly during the incubation phase, and was associated with rainfall and low food availability. In contrast, brood loss during the nestling phase occurred mostly due to low temperatures. Survival of last-hatched nestlings and nestling development was enhanced by food supplementation and reduced by adverse weather conditions. However, we found no support for interactive effects of weather and food availability, suggesting that these factors affect reproduction of red kites additively. The results not only suggest that food-weather interactions are prevented by parental life-history trade-offs, but that food availability and weather conditions are crucial separate determinants of reproductive output, and thus population productivity. Overall, our results suggest that the observed increase in spring temperatures and enhanced anthropogenic food resources have contributed to the elevational expansion and the growth of the study population during the last decades.
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Affiliation(s)
- Melanie Nägeli
- Swiss Ornithological Institute, Seerose 1, 6204, Sempach, Switzerland.,Department of Evolutionary Biology and Environmental Studies, University of Zurich, Wintherthurerstrasse 190, 8057, Zurich, Switzerland
| | - Patrick Scherler
- Swiss Ornithological Institute, Seerose 1, 6204, Sempach, Switzerland. .,Department of Evolutionary Biology and Environmental Studies, University of Zurich, Wintherthurerstrasse 190, 8057, Zurich, Switzerland.
| | - Stephanie Witczak
- Swiss Ornithological Institute, Seerose 1, 6204, Sempach, Switzerland.,Department of Evolutionary Biology and Environmental Studies, University of Zurich, Wintherthurerstrasse 190, 8057, Zurich, Switzerland
| | - Benedetta Catitti
- Swiss Ornithological Institute, Seerose 1, 6204, Sempach, Switzerland.,Department of Evolutionary Biology and Environmental Studies, University of Zurich, Wintherthurerstrasse 190, 8057, Zurich, Switzerland
| | | | | | - Urs Kormann
- Swiss Ornithological Institute, Seerose 1, 6204, Sempach, Switzerland
| | - Martin U Grüebler
- Swiss Ornithological Institute, Seerose 1, 6204, Sempach, Switzerland
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5
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Brood sex ratio modulates the effects of extra food on parental effort and sibling competition in a sexually dimorphic raptor. Behav Ecol Sociobiol 2021. [DOI: 10.1007/s00265-021-02970-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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6
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Mermoz ME, Villarruel C, de la Colina A, Mahler B. Fledgling sex-ratio is biased towards the helping sex in a Neotropical cooperative breeder, the brown-and-yellow marshbird (Pseudoleistes virescens). BEHAVIOUR 2021. [DOI: 10.1163/1568539x-bja10061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Abstract
In many cooperatively breeding species, helpers increase the breeding success of their parents. The repayment hypothesis predicts a skewed sex-ratio towards the helping sex at population level; at individual level bias would increase in broods attended by a smaller number of helpers. We studied a brown-and-yellow marshbird (Pseudoleistes virescens) population during 11 breeding seasons. We found that 90% of helpers were males and that they increased nestling survival, although this effect disappeared in presence of parasitic shiny cowbirds. Helpers sometimes helped at nests of adults other than their parents. Population sex-ratio of fledglings was highly skewed towards males (1.4:1). At individual level, male-biased sex-ratio of fledglings was more pronounced early in the season and increased with brood losses but was not affected by number of helpers. Marshbirds feed at communal areas so retaining helpers would not be costly. Therefore, a general skew towards males might be the best adaptive strategy.
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Affiliation(s)
- Myriam E. Mermoz
- Instituto de Ecología, Genética, y Evolución de Buenos Aires (UBA-CONICET), Intendente Güiraldes 2160 — Ciudad Universitaria — C1428EGA, CABA, Argentina
- Departamento de Ecología, Genética, y Evolución, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Intendente Güiraldes 2160 — C1428EGA Ciudad Universitaria, CABA, Argentina
| | - Cecilia Villarruel
- Departamento de Ecología, Genética, y Evolución, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Intendente Güiraldes 2160 — C1428EGA Ciudad Universitaria, CABA, Argentina
- Current address: Instituto de Fisiología, Biología Molecular y Neurociencias (UBA-CONICET), Intendente Güiraldes 2160 — C1428EGA Ciudad Universitaria, CABA, Argentina
| | - Alicia de la Colina
- Instituto de Ecología, Genética, y Evolución de Buenos Aires (UBA-CONICET), Intendente Güiraldes 2160 — Ciudad Universitaria — C1428EGA, CABA, Argentina
- Current address: Departamento de Conservación e Investigación, Fundación Temaikèn — B1625 Escobar, Prov. de Buenos Aires, Argentina
| | - Bettina Mahler
- Instituto de Ecología, Genética, y Evolución de Buenos Aires (UBA-CONICET), Intendente Güiraldes 2160 — Ciudad Universitaria — C1428EGA, CABA, Argentina
- Departamento de Ecología, Genética, y Evolución, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Intendente Güiraldes 2160 — C1428EGA Ciudad Universitaria, CABA, Argentina
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7
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Golawski A, Mroz E, Golawska S. The function of food storing in shrikes: the importance of larders for the condition of females and during inclement weather. THE EUROPEAN ZOOLOGICAL JOURNAL 2020. [DOI: 10.1080/24750263.2020.1769208] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
Affiliation(s)
- A. Golawski
- Siedlce University of Natural Sciences and Humanities, Faculty of Exact and Natural Sciences, Siedlce, Poland
| | - E. Mroz
- Siedlce University of Natural Sciences and Humanities, Faculty of Exact and Natural Sciences, Siedlce, Poland
| | - S. Golawska
- Siedlce University of Natural Sciences and Humanities, Faculty of Exact and Natural Sciences, Siedlce, Poland
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8
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Direct and indirect effects of temperature and prey abundance on bald eagle reproductive dynamics. Oecologia 2019; 192:391-401. [PMID: 31858230 DOI: 10.1007/s00442-019-04578-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Accepted: 12/05/2019] [Indexed: 10/25/2022]
Abstract
Understanding the mechanisms by which populations are regulated is critical for predicting the effects of large-scale perturbations. While discrete mortality events provide clear evidence of direct impacts, indirect pathways are more difficult to assess but may play important roles in population and ecosystem dynamics. Here, we use multi-state occupancy models to analyze a long-term dataset on nesting bald eagles in south-central Alaska with the goal of identifying both direct and indirect mechanisms influencing reproductive output in this apex predator. We found that the probabilities of both nest occupancy and success were higher in the portion of the study area where water turbidity was low, supporting the hypothesis that access to aquatic prey is a critical factor limiting the reproductive output of eagles in this system. As expected, nest success was also positively related to salmon abundance; however, the negative effect of spring warmth suggested that access to salmon resources is indirectly diminished in warm springs as a consequence of increased glacial melt. Together, these findings reveal complex interrelationships between a critical prey resource and large-scale weather and climate processes which likely alter the accessibility of resources rather than directly affecting resource abundance. While important for understanding bald eagle reproductive dynamics in this system specifically, our results have broader implications that suggest complex interrelationships among system components.
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9
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Hanane S. Multi-scale turtle dove nest habitat selection in a Mediterranean agroforestry landscape: implications for the conservation of a vulnerable species. EUR J WILDLIFE RES 2018. [DOI: 10.1007/s10344-018-1205-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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10
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Grüebler MU, Müller M, Michel VT, Perrig M, Keil H, Naef-Daenzer B, Korner-Nievergelt F. Brood provisioning and reproductive benefits in relation to habitat quality: a food supplementation experiment. Anim Behav 2018. [DOI: 10.1016/j.anbehav.2018.05.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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11
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Affiliation(s)
- Kristen G Dillon
- Arizona Cooperative Fish and Wildlife Research Unit, School of Natural Resources and the Environment, University of Arizona, BioSciences East, Tucson, AZ, USA
- Idaho Cooperative Fish and Wildlife Research Unit, University of Idaho, Perimeter Drive, MS, Moscow, ID, USA
| | - Courtney J Conway
- U. S. Geological Survey, Idaho Cooperative Fish and Wildlife Research Unit, University of Idaho, Perimeter Drive, MS, Moscow, ID, USA
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12
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Ferrer M, Morandini V, Baguena G, Newton I. Reintroducing endangered raptors: A case study of supplementary feeding and removal of nestlings from wild populations. J Appl Ecol 2017. [DOI: 10.1111/1365-2664.13014] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Miguel Ferrer
- Applied Ecology Group; Estación Biológica de Doñana (EBD-CSIC); Seville Spain
| | - Virginia Morandini
- Applied Ecology Group; Estación Biológica de Doñana (EBD-CSIC); Seville Spain
| | - Gerardo Baguena
- Fundación para la Conservación del Quebrantahuesos; Zaragoza Spain
| | - Ian Newton
- Centre for Ecology & Hydrology; Wallingford UK
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13
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Redpath S, Thompson A, Amar A. Female begging calls reflect nutritional need of nestlings in the hen harrier Circus cyaneus. BMC Evol Biol 2017. [PMID: 28629327 PMCID: PMC5477127 DOI: 10.1186/s12862-017-0986-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Most birds exhibit bi-parental care with both sexes providing food for their young. Nestling signal food needs through begging. However, for some species, males rarely visit the nest, so have limited opportunity for gaining information directly from the chicks. Instead, females beg when males deliver food. We tested whether this calling signalled nutritional need and specifically the needs of the female (Breeder Need hypothesis) or that of their chicks (Offspring Need hypothesis). RESULTS We observed begging and provisioning rates at 42 nests of hen harrier (Circus cyaneus) in Scotland, explored the factors associated with variation in begging rate and the relationship between begging and provisioning. We also tested the impact of food on begging and provisioning through a feeding experiment. Female begging rate increased up to a chick age of 3 weeks and then tailed off. In addition, begging increased when broods were large. CONCLUSIONS Our data provided support for the Offspring Need hypothesis. At nests where adlib food was provided females reduced their begging rate. These patterns suggested that female begging was an honest signal of need. However, begging continued even with adlib food and was only weakly associated with greater provisioning by males, suggesting that these calls may also play an additional role, possibly reflecting sexual or parent-offspring conflict.
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Affiliation(s)
- Steve Redpath
- Institute of Biological and Environmental Science, Aberdeen University, Zoology Building, Tillydrone Av, Aberdeen, AB24 2TZ, UK. .,FitzPatrick Institute of African Ornithology, DST/NRF Centre of Excellence, University of Cape Town, Rondebosch, 7701, South Africa. .,Department of Ecology, Swedish University of Agricultural Science, Grimso Wildlife Research Station, -730 91, Riddarhyttan, SE, Sweden.
| | - Alex Thompson
- FitzPatrick Institute of African Ornithology, DST/NRF Centre of Excellence, University of Cape Town, Rondebosch, 7701, South Africa
| | - Arjun Amar
- FitzPatrick Institute of African Ornithology, DST/NRF Centre of Excellence, University of Cape Town, Rondebosch, 7701, South Africa
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14
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Clark RW, Dorr SW, Whitford MD, Freymiller GA, Putman BJ. Activity cycles and foraging behaviors of free-ranging sidewinder rattlesnakes (Crotalus cerastes): the ontogeny of hunting in a precocial vertebrate. ZOOLOGY 2016; 119:196-206. [DOI: 10.1016/j.zool.2016.02.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Revised: 01/15/2016] [Accepted: 02/25/2016] [Indexed: 10/22/2022]
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15
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Jönsson I, Wiehn J, Korpimäki E. Body reserves and unpredictable breeding conditions in the Eurasian kestrel,Falco tinnunculus. ECOSCIENCE 2016. [DOI: 10.1080/11956860.1999.11682545] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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16
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Brodin A, Ingemar Jönsson K, Holmgren N. Optimal energy allocation and behaviour in female raptorial birds during the nestling period. ECOSCIENCE 2016. [DOI: 10.1080/11956860.2003.11682760] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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17
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Mueller AK, Chakarov N, Heseker H, Krüger O. Intraguild predation leads to cascading effects on habitat choice, behaviour and reproductive performance. J Anim Ecol 2016; 85:774-84. [PMID: 26781959 DOI: 10.1111/1365-2656.12493] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Accepted: 11/29/2015] [Indexed: 11/30/2022]
Abstract
Intraguild predation (IGP) is a commonly recognized mechanism influencing the community structure of predators, but the complex interactions are notoriously difficult to disentangle. The mesopredator suppression hypothesis predicts that a superpredator may either simultaneously repress two mesopredators, restrain the dominant one and thereby release the subdominant mesopredator, or elicit different responses by both mesopredators. We show the outcome arising from such conditions in a three-level predator assemblage (Eurasian eagle owl Bubo bubo L., northern goshawk Accipiter gentilis L. and common buzzard Buteo buteo L.) studied over 25 years. In the second half of the study period, the eagle owl re-colonized the study area, thereby providing a natural experiment of superpredator introduction. We combined this set-up with detailed GIS analysis of habitat use and a field experiment simulating intrusion by the superpredator into territories of the subdominant mesopredator, the buzzard. Although population trends were positive for all three species in the assemblage, the proportion of failed breeding attempts increased significantly in both mesopredators after the superpredator re-colonized the area. We predicted that superpredator-induced niche shifts in the dominant mesopredator may facilitate mesopredator coexistence in superpredator-free refugia. We found significant changes in nesting habitat choice in goshawk, but not in buzzard. Since competition for enemy-free refugia and the rapid increase in population density may have constrained niche shifts of the subdominant mesopredator, we further predicted behavioural changes in response to the superpredator. The field experiment indeed showed a significant increase in aggressive response of buzzards towards eagle owl territory intrusion over the course of 10 years, probably due to phenotypic plasticity in the response towards superpredation risk. Overall, our results show that intraguild predation can be a powerful force of behavioural change, simultaneously influencing habitat use and aggressiveness in predator communities. These changes might help to buffer mesopredator populations against the negative effects of intraguild predation.
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Affiliation(s)
- Anna-Katharina Mueller
- Department of Animal Behaviour, Bielefeld University, PO Box 100131, Bielefeld, 33501, Germany
| | - Nayden Chakarov
- Department of Animal Behaviour, Bielefeld University, PO Box 100131, Bielefeld, 33501, Germany.,Department of Biology, Molecular Ecology and Evolution Lab, Lund University, Ecology Building, Lund, SE-22362, Sweden
| | - Hanna Heseker
- Department of Animal Behaviour, Bielefeld University, PO Box 100131, Bielefeld, 33501, Germany
| | - Oliver Krüger
- Department of Animal Behaviour, Bielefeld University, PO Box 100131, Bielefeld, 33501, Germany
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18
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Derbyshire R, Strickland D, Norris DR. Experimental evidence and 43 years of monitoring data show that food limits reproduction in a food-caching passerine. Ecology 2015; 96:3005-15. [DOI: 10.1890/15-0191.1] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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19
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Griffen BD, Norelli AP. Spatially variable habitat quality contributes to within-population variation in reproductive success. Ecol Evol 2015; 5:1474-83. [PMID: 25897386 PMCID: PMC4395176 DOI: 10.1002/ece3.1427] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Revised: 01/21/2015] [Accepted: 01/27/2015] [Indexed: 11/08/2022] Open
Abstract
Variation in habitat quality is common across terrestrial, freshwater, and marine habitats. We investigated how habitat quality influenced the reproductive potential of mud crabs across 30 oyster reefs that were degraded to different extents. We further coupled this field survey with a laboratory experiment designed to mechanistically determine the relationship between resource consumption and reproductive performance. We show a >10-fold difference in average reproductive potential for crabs across reefs of different quality. Calculated consumption rates for crabs in each reef, based on a type II functional response, suggest that differences in reproductive performance may be attributed to resource limitation in poor quality reefs. This conclusion is supported by results of our laboratory experiment where crabs fed a higher quality diet of abundant animal tissue had greater reproductive performance. Our results demonstrate that spatial variation in habitat quality can be a considerable contributor to within-population individual variation in reproductive success (i.e., demographic heterogeneity). This finding has important implications for assessing population extinction risk.
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Affiliation(s)
- Blaine D Griffen
- Department of Biological Sciences, University of South Carolina Columbia, South Carolina, 29208 ; Marine Science Program, University of South Carolina Columbia, South Carolina, 29208
| | - Alexandra P Norelli
- Marine Science Program, University of South Carolina Columbia, South Carolina, 29208
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20
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Evolution of parental roles in raptors: prey type determines role asymmetry in the Eurasian kestrel. Anim Behav 2014. [DOI: 10.1016/j.anbehav.2014.07.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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21
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Ferrer M, Newton I, Muriel R, Báguena G, Bustamante J, Martini M, Morandini V. Using manipulation of density-dependent fecundity to recover an endangered species: the bearded vultureGypaetus barbatusas an example. J Appl Ecol 2014. [DOI: 10.1111/1365-2664.12308] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Miguel Ferrer
- Department of Ethology and Biodiversity Conservation; Estación Biológica de Doñana (EBD-CSIC); C/Americo Vespucio s/n 41092 Seville Spain
| | - Ian Newton
- Centre for Ecology & Hydrology; Benson Lane; Crowmarsh Gifford Wallingford OX10 8BB UK
| | - Roberto Muriel
- Department of Ethology and Biodiversity Conservation; Estación Biológica de Doñana (EBD-CSIC); C/Americo Vespucio s/n 41092 Seville Spain
| | - Gerardo Báguena
- Fundación para la Conservación del Quebrantahuesos; Plaza San Pedro Nolasco 1, 4°F 50001 Zaragoza Spain
| | - Javier Bustamante
- Department of Wetland Ecology; Estación Biológica de Doñana (EBD-CSIC); C/Americo Vespucio s/n 41092 Seville Spain
| | - Matilde Martini
- Department of Ethology and Biodiversity Conservation; Estación Biológica de Doñana (EBD-CSIC); C/Americo Vespucio s/n 41092 Seville Spain
| | - Virginia Morandini
- Department of Ethology and Biodiversity Conservation; Estación Biológica de Doñana (EBD-CSIC); C/Americo Vespucio s/n 41092 Seville Spain
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22
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Sonerud GA, Steen R, Selås V, Aanonsen OM, Aasen GH, Fagerland KL, Fosså A, Kristiansen L, Løw LM, Rønning ME, Skouen SK, Asakskogen E, Johansen HM, Johnsen JT, Karlsen LI, Nyhus GC, Røed LT, Skar K, Sveen BA, Tveiten R, Slagsvold T. Evolution of parental roles in provisioning birds: diet determines role asymmetry in raptors. Behav Ecol 2014. [DOI: 10.1093/beheco/aru053] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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23
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Trophic niche width, offspring condition and immunity in a raptor species. Oecologia 2013; 174:1215-24. [PMID: 24368708 DOI: 10.1007/s00442-013-2855-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Accepted: 12/02/2013] [Indexed: 10/25/2022]
Abstract
Strategies developed by organisms to maximize foraging efficiency have a strong influence on fitness. The way in which the range of food resources is exploited has served to classify species, populations and individuals from more specialist (narrow trophic niche) to more generalist (broad trophic niche). Recent studies have provided evidence that many of the considered generalist species/populations are actually composed of different specialist individuals (individual specialization). Even the existence of generalism as an adaptive strategy has been questioned. In this study, we investigated the relationship between trophic niche width, individual quality and offspring viability in a population of common kestrel Falco tinnunculus during 4 years. We showed that the diet of kestrels varied significantly among years and that individuals of better quality fed their offspring with a higher diversity of prey species and a higher amount of food. Moreover, body condition and immune response of nestlings were positively correlated with diversity of prey delivered by parents. Our study suggests that generalism has the potential to increase fitness and that broadening the trophic niche may be an adaptive strategy in unpredictable environments.
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24
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Wellicome TI, Danielle Todd L, Poulin RG, Holroyd GL, Fisher RJ. Comparing food limitation among three stages of nesting: supplementation experiments with the burrowing owl. Ecol Evol 2013; 3:2684-95. [PMID: 24567832 PMCID: PMC3930041 DOI: 10.1002/ece3.616] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2013] [Revised: 04/08/2013] [Accepted: 04/17/2013] [Indexed: 11/25/2022] Open
Abstract
Food availability is an important limiting factor for avian reproduction. In altricial birds, food limitation is assumed to be more severe during the nestling stage than during laying or incubation, but this has yet to be adequately tested. Using food-supplementation experiments over a 5-year period, we determined the degree and timing of food limitation for burrowing owls (Athene cunicularia) breeding in Canada. Burrowing owls are an endangered species and food limitation during the nestling stage could influence reproductive performance of this species at the northern extent of their range. Supplemented pairs fledged on average 47% more owlets than unfed pairs, except during a year when natural food was not limiting (i.e., a prey irruption year). The difference in fledgling production resulted from high nestling mortality in unfed broods, with 96% of all nestling deaths being attributed to food shortage. Supplemental feeding during the nestling period also increased fledgling structural size. Pairs fed from the start of laying produced the same number of hatchlings as pairs that received no supplemental food before hatch. Furthermore, pairs supplemented from egg laying to fledging and pairs supplemented during the nestling period alone had the same patterns of nestling survival, equal numbers of fledglings, and similar fledgling mass and structural size. Our results provide empirical support for the hypothesis that the nestling period is the most food-limited phase of the breeding cycle. The experimental design we introduce here could be used with other altricial species to examine how the timing of food limitation differs among birds with a variety of life-history strategies. For burrowing owls, and other species with similar life histories, long-term, large-scale, and appropriately timed habitat management increasing prey abundance or availability is critical for conservation. Our results provide empirical support for the hypothesis that the nestling period is the most food-limited phase of the breeding cycle. For burrowing owls, and other species with similar life histories, long-term, large-scale, and appropriately timed habitat management increasing prey abundance or availability is critical for conservation.
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Affiliation(s)
- Troy I Wellicome
- Department of Biological Sciences, University of Alberta T6G 2E9, Edmonton, Canada ; Canadian Wildlife Service Room 200, 4999-98th Ave., T6B 2X3, Edmonton, Canada
| | - L Danielle Todd
- Department of Biology, University of Regina S4S 0A2, Regina, Canada
| | - Ray G Poulin
- Department of Biology, University of Regina S4S 0A2, Regina, Canada ; Royal Saskatchewan Museum 2340 Albert St., S4P 2V7, Regina, Canada
| | - Geoffrey L Holroyd
- Canadian Wildlife Service Room 200, 4999-98th Ave., T6B 2X3, Edmonton, Canada
| | - Ryan J Fisher
- Department of Biological Sciences, University of Alberta T6G 2E9, Edmonton, Canada
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Sonerud GA, Steen R, Løw LM, Røed LT, Skar K, Selås V, Slagsvold T. Size-biased allocation of prey from male to offspring via female: family conflicts, prey selection, and evolution of sexual size dimorphism in raptors. Oecologia 2012; 172:93-107. [PMID: 23073637 DOI: 10.1007/s00442-012-2491-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2012] [Accepted: 09/27/2012] [Indexed: 10/27/2022]
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26
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Sternalski A, Mougeot F, Bretagnolle V. Phenotypic variation in nestlings of a bird of prey under contrasting breeding and diet conditions. Biol J Linn Soc Lond 2012. [DOI: 10.1111/j.1095-8312.2012.01981.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | - François Mougeot
- Estación Experimental de Zonas Áridas (EEZA-CSIC); Carretera de Sacramento s/n; 04120 La Cañada de San Urbano; Almería; Spain
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Kross SM, Tylianakis JM, Nelson XJ. Translocation of threatened New Zealand falcons to vineyards increases nest attendance, brooding and feeding rates. PLoS One 2012; 7:e38679. [PMID: 22719921 PMCID: PMC3375302 DOI: 10.1371/journal.pone.0038679] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2012] [Accepted: 05/14/2012] [Indexed: 11/18/2022] Open
Abstract
Anthropogenic landscapes can be rich in resources, and may in some cases provide potential habitat for species whose natural habitat has declined. We used remote videography to assess whether reintroducing individuals of the threatened New Zealand falcon Falco novaeseelandiae into a highly modified agricultural habitat affected the feeding rates of breeding falcons or related breeding behavior such as nest attendance and brooding rates. Over 2,800 recording hours of footage were used to compare the behavior of falcons living in six natural nests (in unmanaged, hilly terrain between 4 km and 20 km from the nearest vineyard), with that of four breeding falcon pairs that had been transported into vineyards and nested within 500 m of the nearest vineyard. Falcons in vineyard nests had higher feeding rates, higher nest attendance, and higher brooding rates. As chick age increased, parents in vineyard nests fed chicks a greater amount of total prey and larger prey items on average than did parents in hill nests. Parents with larger broods brought in larger prey items and a greater total sum of prey biomass. Nevertheless, chicks in nests containing siblings received less daily biomass per individual than single chicks. Some of these results can be attributed to the supplementary feeding of falcons in vineyards. However, even after removing supplementary food from our analysis, falcons in vineyards still fed larger prey items to chicks than did parents in hill nests, suggesting that the anthropogenic habitat may be a viable source of quality food. Although agricultural regions globally are rarely associated with raptor conservation, these results suggest that translocating New Zealand falcons into vineyards has potential for the conservation of this species.
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Affiliation(s)
- Sara M Kross
- School of Biological Sciences, University of Canterbury, Christchurch, New Zealand.
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28
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Condition-dependent expression of melanin-based coloration in the Eurasian kestrel. Naturwissenschaften 2012; 99:391-6. [DOI: 10.1007/s00114-012-0914-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Revised: 04/02/2012] [Accepted: 04/03/2012] [Indexed: 10/28/2022]
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Santangeli A, Hakkarainen H, Laaksonen T, Korpimäki E. Home range size is determined by habitat composition but feeding rate by food availability in male Tengmalm’s owls. Anim Behav 2012. [DOI: 10.1016/j.anbehav.2012.02.002] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Epanchin PN, Knapp RA, Lawler SP. Nonnative trout impact an alpine-nesting bird by altering aquatic-insect subsidies. Ecology 2010; 91:2406-15. [PMID: 20836462 DOI: 10.1890/09-1974.1] [Citation(s) in RCA: 125] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Adjacent food webs may be linked by cross-boundary subsidies: more-productive donor systems can subsidize consumers in less-productive neighboring recipient systems. Introduced species are known to have direct effects on organisms within invaded communities. However, few studies have addressed the indirect effects of nonnative species in donor systems on organisms in recipient systems. We studied the direct role of introduced trout in altering a lake-derived resource subsidy and their indirect effects in altering a passerine bird's response to that subsidy. We compared the abundance of aquatic insects and foraging Gray-crowned Rosy-Finches (Leucosticte tephrocotis dawsoni, "Rosy-Finch") at fish-containing vs. fishless lakes in the Sierra Nevada Mountains of California (USA). Introduced trout outcompeted Rosy-Finches for emerging aquatic insects (i.e., mayflies). Fish-containing lakes had 98% fewer mayflies than did fishless lakes. In lakes without fish, Rosy-Finches showed an aggregative response to emerging aquatic insects with 5.9 times more Rosy-Finches at fishless lakes than at fish-containing lakes. Therefore, the introduction of nonnative fish into the donor system reduced both the magnitude of the resource subsidy and the strength of cross-boundary trophic interactions. Importantly, the timing of the subsidy occurs when Rosy-Finches feed their young. If Rosy-Finches rely on aquatic-insect subsidies to fledge their young, reductions in the subsidy by introduced trout may have decreased Rosy-Finch abundances from historic levels. We recommend that terrestrial recipients of aquatic subsidies be included in conservation and restoration plans for ecosystems with alpine lakes.
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Affiliation(s)
- Peter N Epanchin
- Graduate Group in Ecology, Department of Entomology, University of California, Davis, One Shields Avenue, Davis, California 95616, USA.
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31
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Vergara P, Fargallo JA, Martínez-Padilla J. Reaching independence: food supply, parent quality, and offspring phenotypic characters in kestrels. Behav Ecol 2010. [DOI: 10.1093/beheco/arq011] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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32
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Supplementary feeding during the chick-rearing period is ineffective in increasing the breeding success in the bearded vulture (Gypaetus barbatus). EUR J WILDLIFE RES 2010. [DOI: 10.1007/s10344-010-0366-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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33
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Experimental increase in food supply influences the outcome of within-family conflicts in Tengmalm’s owl. Behav Ecol Sociobiol 2010. [DOI: 10.1007/s00265-009-0898-z] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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34
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Solonen T. Factors Affecting Reproduction in the Tawny OwlStrix alucoin Southern Finland. ANN ZOOL FENN 2009. [DOI: 10.5735/086.046.0407] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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35
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Covariation between eumelanic pigmentation and body mass only under specific conditions. Naturwissenschaften 2009; 96:375-82. [PMID: 19122994 DOI: 10.1007/s00114-008-0489-2] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2008] [Revised: 11/17/2008] [Accepted: 11/24/2008] [Indexed: 02/06/2023]
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Karell P, Pietiäinen H, Siitari H, Pihlaja T, Kontiainen P, Brommer JE. Parental allocation of additional food to own health and offspring growth in a variable environment. CAN J ZOOL 2009. [DOI: 10.1139/z08-133] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Life-history theory predicts increased investment in current reproduction when future reproduction is uncertain and a more balanced investment in current and future reproduction when prospects for both are good. The outcome of the balance in parental allocation depends on which life-history component maximizes the fitness benefits. In our study system, a 3-year vole cycle generates good prospects of current and future reproduction for Ural owls ( Strix uralensis Pallas, 1771) in increase vole phases and uncertain prospects in decrease vole phases. We supplementary-fed Ural owls during the nestling period in 2002 (an increase phase) and 2003 (a decrease phase), and measured offspring growth, parental effort, and physiological health by monitoring haematocrit, leucocyte profiles, intra- and inter-celluar blood parasites, and (in 2003) humoral antibody responsiveness. Food supplementation reduced parental feeding rate in both years, but improved a female parent’s health only in 2002 (an increase phase) and had no effects on males in either year. Nevertheless, supplementary-fed offspring reached higher asymptotic mass and fledged earlier in both years. Furthermore, early fledging reduced offspring exposure to blood-sucking black flies (Diptera, Simuliidae) in the nest. We discuss how parental allocation of resources to current and future reproduction may vary under variable food conditions.
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Affiliation(s)
- Patrik Karell
- Bird Ecology Unit, Department of Biological and Environmental Sciences, University of Helsinki, P.O. Box 65 (Viikinkaari 1), 00014 Helsinki, Finland
- Evolutionary Research Unit, Department of Biological and Environmental Sciences, University of Jyväskylä, P.O. Box 35, 40014 Jyväskylä, Finland
| | - Hannu Pietiäinen
- Bird Ecology Unit, Department of Biological and Environmental Sciences, University of Helsinki, P.O. Box 65 (Viikinkaari 1), 00014 Helsinki, Finland
- Evolutionary Research Unit, Department of Biological and Environmental Sciences, University of Jyväskylä, P.O. Box 35, 40014 Jyväskylä, Finland
| | - Heli Siitari
- Bird Ecology Unit, Department of Biological and Environmental Sciences, University of Helsinki, P.O. Box 65 (Viikinkaari 1), 00014 Helsinki, Finland
- Evolutionary Research Unit, Department of Biological and Environmental Sciences, University of Jyväskylä, P.O. Box 35, 40014 Jyväskylä, Finland
| | - Tuomo Pihlaja
- Bird Ecology Unit, Department of Biological and Environmental Sciences, University of Helsinki, P.O. Box 65 (Viikinkaari 1), 00014 Helsinki, Finland
- Evolutionary Research Unit, Department of Biological and Environmental Sciences, University of Jyväskylä, P.O. Box 35, 40014 Jyväskylä, Finland
| | - Pekka Kontiainen
- Bird Ecology Unit, Department of Biological and Environmental Sciences, University of Helsinki, P.O. Box 65 (Viikinkaari 1), 00014 Helsinki, Finland
- Evolutionary Research Unit, Department of Biological and Environmental Sciences, University of Jyväskylä, P.O. Box 35, 40014 Jyväskylä, Finland
| | - Jon E. Brommer
- Bird Ecology Unit, Department of Biological and Environmental Sciences, University of Helsinki, P.O. Box 65 (Viikinkaari 1), 00014 Helsinki, Finland
- Evolutionary Research Unit, Department of Biological and Environmental Sciences, University of Jyväskylä, P.O. Box 35, 40014 Jyväskylä, Finland
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37
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Affiliation(s)
- T C R White
- School of Agriculture Food and Wine, Waite Agricultural Research Institute, The University of Adelaide, Glen Osmond, South Australia 5064, Australia.
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Laaksonen T, Negro JJ, Lyytinen S, Valkama J, Ots I, Korpimäki E. Effects of experimental brood size manipulation and gender on carotenoid levels of Eurasian kestrels Falco tinnunculus. PLoS One 2008; 3:e2374. [PMID: 18545646 PMCID: PMC2396282 DOI: 10.1371/journal.pone.0002374] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2008] [Accepted: 04/24/2008] [Indexed: 11/19/2022] Open
Abstract
Background Animals use carotenoid-pigments for coloration, as antioxidants and as enhancers of the immune system. Carotenoid-dependent colours can thus signal individual quality and carotenoids have also been suggested to mediate life-history trade-offs. Methodology To examine trade-offs in carotenoid allocation between parents and the young, or between skin coloration and plasma of the parents at different levels of brood demand, we manipulated brood sizes of Eurasian kestrels (Falco tinnunculus). Principal Findings Brood size manipulation had no overall effect on plasma carotenoid levels or skin hue of parents, but female parents had twice the plasma carotenoid levels of males. Males work physically harder than females and they might thus also use more carotenoids against oxidative stress than females. Alternatively, females could be gaining back the carotenoid stores they depleted during egg-laying by eating primarily carotenoid-rich food items during the early nestling stage. Fledglings in enlarged broods had higher plasma carotenoid concentrations than those in reduced broods. This difference was not explained by diet. In light of recent evidence from other species, we suggest it might instead be due to fledglings in enlarged broods having higher testosterone levels, which in turn increased plasma carotenoid levels. The partial cross-foster design of our experiment revealed evidence for origin effects (genetic or maternal) on carotenoid levels of fledglings, but no origin-environment interaction. Significance These results from wild birds differ from studies in captivity, and thus offer new insights into carotenoid physiology in relation to division of parental care and demands of the brood.
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Affiliation(s)
- Toni Laaksonen
- Section of Ecology, Department of Biology, University of Turku, Turku, Finland.
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Byholm P, Kekkonen M. FOOD REGULATES REPRODUCTION DIFFERENTLY IN DIFFERENT HABITATS: EXPERIMENTAL EVIDENCE IN THE GOSHAWK. Ecology 2008; 89:1696-702. [PMID: 18589533 DOI: 10.1890/07-0675.1] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
- Patrik Byholm
- University of Helsinki, Bird Ecology Unit, Department of Biological and Environmental Sciences, Helsinki, Finland.
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40
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Vergara P, Fargallo JA. Sex, melanic coloration, and sibling competition during the postfledging dependence period. Behav Ecol 2008. [DOI: 10.1093/beheco/arn035] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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41
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Sockman KW, Sharp PJ, Schwabl H. Orchestration of avian reproductive effort: an integration of the ultimate and proximate bases for flexibility in clutch size, incubation behaviour, and yolk androgen deposition. Biol Rev Camb Philos Soc 2007. [DOI: 10.1111/j.1469-185x.2006.tb00221.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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42
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Mock DW, Schwagmeyer P, Parker G. Male house sparrows deliver more food to experimentally subsidized offspring. Anim Behav 2005. [DOI: 10.1016/j.anbehav.2004.10.020] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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43
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Steinhart GB, Sandrene ME, Weaver S, Stein RA, Marschall EA. Increased parental care cost for nest-guarding fish in a lake with hyperabundant nest predators. Behav Ecol 2004. [DOI: 10.1093/beheco/ari006] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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44
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45
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G. MCDonald P, Olsen PD, Cockburn A. Weather dictates reproductive success and survival in the Australian brown falcon Falco berigora. J Anim Ecol 2004. [DOI: 10.1111/j.0021-8790.2004.00842.x] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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46
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Durant JM, Gendner JP, Handrich Y. Should I brood or should I hunt: a female barn owl's dilemma. CAN J ZOOL 2004. [DOI: 10.1139/z04-078] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
While brooding, many female raptors rely exclusively on food provisioning from males. Thus, they may forego hunting until young are about half grown before exiting the nest to undertake a first foraging trip. To investigate the mechanisms that trigger this first foraging exit, we analysed nest food provisioning, female body mass change, and nestling and female food requirements in regard to exit date in five pairs of barn owls, Tyto alba (Scopoli, 1769), nesting in eastern France. Adult mass and behaviour were monitored using an automated weighing system and a video camera. Our results indicate that the first foraging exit of the female occurs about 15 days after the hatching of the first egg. This reinitiation of foraging occurs at about the same time that male food provisioning no longer matches nestling food requirements — about 17 days after the hatching of the first egg. Thus the timing of the female's first hunting trip may be primarily adjusted to a discrepancy between brood food requirements and available food supply. Additionally, we found that females started to lose mass, on average, 6 days before their first hunting trip through a reduction of food intake, and we discuss the potential mechanisms and implications.
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47
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Laaksonen T, Lyytinen S, Korpimäki E. Sex-Specific Recruitment and Brood Sex Ratios of Eurasian Kestrels in a Seasonally and Annually Fluctuating Northern Environment. Evol Ecol 2004. [DOI: 10.1023/b:evec.0000035081.91292.17] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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48
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Rosenberg DK, Swindle KA, Anthony RG. Influence of prey abundance on northern spotted owl reproductive success in western Oregon. CAN J ZOOL 2003. [DOI: 10.1139/z03-167] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The hypothesis that high temporal variability of northern spotted owl (Strix occidentalis caurina) reproductive success is a response to prey abundance remains largely untested. We evaluated this relationship in the Oregon Cascade Mountains. Despite similar biomass of northern flying squirrels (Glaucomys sabrinus) (169 ± 13.9 g/ha) and deer mice (Peromyscus maniculatus) (160 ± 18.8 g/ha), flying squirrels dominated the breeding season diet based on both biomass (49%) and numbers (40%). Abundance of flying squirrels and western red-backed voles (Clethrionomys californicus) was more variable spatially ([Formula: see text]38% of process variation) than temporally (15%–24%), whereas abundance of deer mice was more similar across stands (12% spatial variation) than among years (68% temporal variation). Spotted owl reproductive success was statistically associated only with the abundance of deer mice (number of young per territory: r2 = 0.68). However, deer mice comprised only 1.6 ± 0.5% of the biomass consumed. The low temporal variability of the dominant prey species provided evidence that simple prey relationship models were not likely to explain the highly synchronous and temporally dynamic patterns of spotted owl reproductive performance. Reproductive success was likely a result of the interaction of both weather and prey and the life history strategy of this long-lived owl.
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49
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Dawson RD, Bortolotti GR. Parental effort of American kestrels: the role of variation in brood size. CAN J ZOOL 2003. [DOI: 10.1139/z03-064] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Brood size has the potential to determine the allocation of resources between parents and offspring, as well as influence the relative contributions of each sex to parental effort. However, it is unclear whether brood size is the proximate determinant of parental effort, or conversely whether parental effort is the proximate factor to which brood size is adjusted. If brood size determines parental effort, then theory suggests that parental effort should vary with experimental changes in brood size. In contrast, if parental effort determines brood size, then parental effort is expected to be independent of experimental variation in brood size. To distinguish between these hypotheses, we experimentally reduced brood sizes of American kestrels (Falco sparverius). Our results suggest that male parents responded to brood-size variation and adjusted their provisioning behaviour accordingly. Conversely, female parents did not adjust provisioning in response to brood size, and as a result, offspring in reduced broods received more food on a per-nestling basis. However, condition and survival of offspring were similar in reduced broods and control young, which may have been the result of larger food requirements of small broods, owing to increased thermoregulatory costs compared with control broods. Female parents with reduced broods also did not brood offspring more often, further suggesting that females do not respond to variation in brood size. We conclude that the proximate determinants of parental effort are sex-specific in American kestrels: for males, brood size determines behaviour, whereas for females, behaviour may be a proximate factor determining brood size.
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50
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Sunde P, Bølstad MS, Møller JD. Reversed sexual dimorphism in tawny owls, Strix aluco
, correlates with duty division in breeding effort. OIKOS 2003. [DOI: 10.1034/j.1600-0706.2003.12203.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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