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Knutie SA, Webster CN, Vaziri GJ, Albert L, Harvey JA, LaRue M, Verrett TB, Soldo A, Koop JAH, Chaves JA, Wegrzyn JL. Urban living can rescue Darwin's finches from the lethal effects of invasive vampire flies. GLOBAL CHANGE BIOLOGY 2024; 30:e17145. [PMID: 38273516 DOI: 10.1111/gcb.17145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 12/15/2023] [Accepted: 12/21/2023] [Indexed: 01/27/2024]
Abstract
Human activity changes multiple factors in the environment, which can have positive or negative synergistic effects on organisms. However, few studies have explored the causal effects of multiple anthropogenic factors, such as urbanization and invasive species, on animals and the mechanisms that mediate these interactions. This study examines the influence of urbanization on the detrimental effect of invasive avian vampire flies (Philornis downsi) on endemic Darwin's finches in the Galápagos Islands. We experimentally manipulated nest fly abundance in urban and non-urban locations and then characterized nestling health, fledging success, diet, and gene expression patterns related to host defense. Fledging success of non-parasitized nestlings from urban (79%) and non-urban (75%) nests did not differ significantly. However, parasitized, non-urban nestlings lost more blood, and fewer nestlings survived (8%) compared to urban nestlings (50%). Stable isotopic values (δ15 N) from urban nestling feces were higher than those from non-urban nestlings, suggesting that urban nestlings are consuming more protein. δ15 N values correlated negatively with parasite abundance, which suggests that diet might influence host defenses (e.g., tolerance and resistance). Parasitized, urban nestlings differentially expressed genes within pathways associated with red blood cell production (tolerance) and pro-inflammatory response (innate immunological resistance), compared to parasitized, non-urban nestlings. In contrast, parasitized non-urban nestlings differentially expressed genes within pathways associated with immunoglobulin production (adaptive immunological resistance). Our results suggest that urban nestlings are investing more in pro-inflammatory responses to resist parasites but also recovering more blood cells to tolerate blood loss. Although non-urban nestlings are mounting an adaptive immune response, it is likely a last effort by the immune system rather than an effective defense against avian vampire flies since few nestlings survived.
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Affiliation(s)
- Sarah A Knutie
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, Connecticut, USA
- Institute for Systems Genomics, University of Connecticut, Storrs, Connecticut, USA
| | - Cynthia N Webster
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, Connecticut, USA
| | - Grace J Vaziri
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, Connecticut, USA
| | - Lauren Albert
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, Connecticut, USA
| | - Johanna A Harvey
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, Connecticut, USA
- Department of Science and Technology, University of Maryland, College Park, Maryland, USA
| | - Michelle LaRue
- School of Earth and Environment, University of Canterbury, Christchurch, New Zealand
| | - Taylor B Verrett
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, Connecticut, USA
| | - Alexandria Soldo
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, Connecticut, USA
| | - Jennifer A H Koop
- Department of Biological Sciences, Northern Illinois University, DeKalb, Illinois, USA
| | - Jaime A Chaves
- Department of Biology, San Francisco State University, San Francisco, California, USA
- Colegio de Ciencias Biológicas y Ambientales, Universidad San Francisco de Quito, Quito, Ecuador
| | - Jill L Wegrzyn
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, Connecticut, USA
- Institute for Systems Genomics, University of Connecticut, Storrs, Connecticut, USA
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Sumasgutner P, Nilles T, Hykollari A, de Chapa MM, Isaksson C, Hochleitner L, Renner S, Fusani L. Integument colouration and circulating carotenoids in relation to urbanisation in Eurasian kestrels (Falco tinnunculus). THE SCIENCE OF NATURE - NATURWISSENSCHAFTEN 2023; 110:48. [PMID: 37736824 PMCID: PMC10516791 DOI: 10.1007/s00114-023-01874-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Revised: 09/03/2023] [Accepted: 09/04/2023] [Indexed: 09/23/2023]
Abstract
Urbanisation is one of the biggest environmental challenges of our time, yet we still lack an integrative understanding of how cities affect behaviour, physiology and parasite susceptibility of free-living organisms. In this study, we focus on carotenoids, strictly dietary micronutrients that can either be used as yellow-red pigments, for integument colouration (signalling function), or as antioxidants, to strengthen the immune system (physiological function) in an urban predator, the Eurasian kestrel (Falco tinnunculus). Kestrels are specialised vole hunters but shift to avian prey in cities where diurnal rodents are not sufficiently available. This different foraging strategy might determine the quantity of carotenoids available. We measured integument colouration, circulating carotenoids in the blood and ectoparasite burden in kestrels along an urban gradient. Our results showed that nestlings that were raised in more urbanised areas displayed, unrelated to their ectoparasite burden, a paler integument colouration. Paler colours were furthermore associated with a lower concentration of circulating carotenoids. These findings support the hypothesis that the entire urban food web is carotenoid deprived and only prey of low quality with low carotenoid content is available (e.g. fewer carotenoids in urban trees, insects, small birds and finally kestrels). The alternative hypothesis that nestlings allocate carotenoids to reduce physiological stress and/or to cope with parasites rather than invest into colouration could not be supported. Our study adds to existing evidence that urban stressors negatively affect carotenoid production in urban areas, a deficiency that dissipate into higher trophic levels.
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Affiliation(s)
- Petra Sumasgutner
- Konrad Lorenz Research Center, Core Facility for Behavior and Cognition, University of Vienna, Grünau/Almtal, Vienna, Austria.
- Department of Behavioral and Cognitive Biology, University of Vienna, Vienna, Austria.
- Natural History Museum Vienna, Vienna, Austria.
| | - Tom Nilles
- Konrad Lorenz Research Center, Core Facility for Behavior and Cognition, University of Vienna, Grünau/Almtal, Vienna, Austria
- Department of Behavioral and Cognitive Biology, University of Vienna, Vienna, Austria
- Natural History Museum Vienna, Vienna, Austria
| | - Alba Hykollari
- Research Institute of Wildlife Ecology, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Manuela Merling de Chapa
- Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany
- Hessian Agency for Nature, Environment and Geology, Biodiversity Center, Giessen, Germany
| | | | - Lukas Hochleitner
- Natural History Museum Vienna, Vienna, Austria
- Research Institute of Wildlife Ecology, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Swen Renner
- Natural History Museum Vienna, Vienna, Austria
| | - Leonida Fusani
- Department of Behavioral and Cognitive Biology, University of Vienna, Vienna, Austria
- Konrad Lorenz Institute of Ethology, University of Veterinary Medicine, Vienna, Austria
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Urban Birds Using Insects on Front Panels of Cars. BIRDS 2023. [DOI: 10.3390/birds4010002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Urbanization influences the food availability and quality for birds in many ways. Although a great amount of food for birds is provided incidentally or intentionally in urban areas, the quantity of insect-based food can be reduced in cities. We studied the role of one artificial food source, insects smashed on the front panels of cars, in Finland, and more specifically in the city of Rovaniemi, by conducting questionnaire research, searching for data from databases and performing a field study. Our results indicated that a total of seven bird species have been detected using insects on the front panels of cars in Finland. However, this behavior is not yet common since about 60% of responders to the questionnaire stated that this behavior is currently either rare or very rare. Most of the observations identified House Sparrows, followed by the White Wagtail or the Eurasian Jackdaw. Only a few observations identified the Eurasian Tree Sparrow, the Hooded Crow, the Great Tit and the Eurasian Magpie. The phenomenon was distributed quite widely across Finland, except in the case of the Eurasian Jackdaws, for which observations were restricted only to the southern part of the country. The first observation was made about the House Sparrow in 1971, followed by the White Wagtail (1975), Hooded Crow (1997), Eurasian Jackdaw (2006), Eurasian Tree Sparrow (2011), Eurasian Magpie (2019) and Great Tit (2022). The species using this food source are mainly sedentary urban exploiters, such as corvids and sparrows, that have been previously reported to have several different types of innovative behaviors. Most of the observations were conducted in urban parking sites of hypermarkets, and no observations were made in residential areas. Most of the foraging observations were made during the end phase of the breeding season, partly supporting the extra need for high-quality insect-based food for nestlings and fledglings. Our observations indicate that this behavior is not yet common and widespread among species.
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Parenting in the city: effects of urbanization on incubation behaviour and egg temperature in great tits, Parus major. Anim Behav 2022. [DOI: 10.1016/j.anbehav.2022.09.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Jain V, Bugnyar T, Cunningham SJ, Gallego-Abenza M, Loretto MC, Sumasgutner P. The spatial and temporal exploitation of anthropogenic food sources by common ravens (Corvus corax) in the Alps. MOVEMENT ECOLOGY 2022; 10:35. [PMID: 36008849 PMCID: PMC9414151 DOI: 10.1186/s40462-022-00335-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Accepted: 08/05/2022] [Indexed: 06/15/2023]
Abstract
BACKGROUND Anthropogenic food sources (AFSs) are widespread in human-transformed landscapes and the current scale at which they occur drives ecological change at the individual, population, and community levels. AFSs are exploited extensively by common ravens, Corvus corax. Understanding how raven populations use AFSs can provide insight into their ecological responses to AFSs. METHODS We equipped 81 ravens in the Austrian Alps with GPS-transmitters over a period of 2.75 years. Using these tracking data, we investigated how cohort differences (i.e., age, sex, and origin) and seasonal changes influence raven movement patterns (i.e., occurrence distribution and maximum daily displacement) and AFS-use (i.e., number of AFSs visited and probability of being present at any AFS) at 45 extensively exploited sites. RESULTS We found that proxies for experience and dominance, inferred by age (i.e., juvenile versus adult) and origin (i.e., wild-caught versus captive-bred-released) cohorts, influenced movement patterns and the number of AFSs visited. However, all individuals were equally likely to be present at AFSs, highlighting the importance of AFSs for non-breeders in the study population. Seasonal changes in environmental conditions that affect energetic demands, the availability of natural and anthropogenic food, and foraging competition, influenced individuals' occurrence distributions and AFS-use. We found that under harsher conditions in autumn and winter, individuals ranged wider and depended on AFSs to a larger degree. However, contrary to expectation, they were less likely to be present at AFSs in these seasons compared to spring and summer, suggesting a trade-off between time spent moving and exploiting resources. We attribute the small ranging movements exhibited by non-breeders in spring and summer to the presence of highly territorial and socially dominant breeders. As breeders mostly stay and forage within their territories during these seasons, competition at AFSs decrease, thereby increasing the likelihood of individuals being present at any AFS. CONCLUSIONS We emphasize that movement and AFS-use differ according to cohort differences and the seasonality of the environment. Our results highlight that predictable AFSs affect foraging strategies among non-breeding ravens. The extent of AFS-exploitation among non-breeding ravens in our study emphasize the potential of AFSs in shaping raven movement and resource-use.
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Affiliation(s)
- Varalika Jain
- FitzPatrick Institute of African Ornithology, DSI-NRF Centre of Excellence, Private Bax X3, Rondebosch, Cape Town, 7701, South Africa.
- Core Facility for Behaviour and Cognition, Konrad Lorenz Research Centre, University of Vienna, Fischerau 13, 4645, Grünau im Almtal, Austria.
| | - Thomas Bugnyar
- Core Facility for Behaviour and Cognition, Konrad Lorenz Research Centre, University of Vienna, Fischerau 13, 4645, Grünau im Almtal, Austria
- Department of Behavioural and Cognitive Biology, University of Vienna, Djerasi Platz 1, 1030, Vienna, Austria
| | - Susan J Cunningham
- FitzPatrick Institute of African Ornithology, DSI-NRF Centre of Excellence, Private Bax X3, Rondebosch, Cape Town, 7701, South Africa
| | - Mario Gallego-Abenza
- Core Facility for Behaviour and Cognition, Konrad Lorenz Research Centre, University of Vienna, Fischerau 13, 4645, Grünau im Almtal, Austria
- Department of Behavioural and Cognitive Biology, University of Vienna, Djerasi Platz 1, 1030, Vienna, Austria
- Department of Zoology, Stockholm University, Stockholm, Sweden
| | - Matthias-Claudio Loretto
- Ecosystem Dynamics and Forest Management Group, TUM School of Life Sciences, Technical University of Munich, Hans-Carl-von-Carlowitz-Platz 2, 85354, Freising, Germany
- Berchtesgaden National Park, Doktorberg 6, 83471, Berchtesgaden, Germany
| | - Petra Sumasgutner
- Core Facility for Behaviour and Cognition, Konrad Lorenz Research Centre, University of Vienna, Fischerau 13, 4645, Grünau im Almtal, Austria
- Department of Behavioural and Cognitive Biology, University of Vienna, Djerasi Platz 1, 1030, Vienna, Austria
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