Ecological and evolutionary implications of anthropogenic food subsidies on wildlife: the white stork as a case study

Martins, Bruno Herlander Mira (2024) Ecological and evolutionary implications of anthropogenic food subsidies on wildlife: the white stork as a case study. Doctoral thesis, University of East Anglia.

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Human activities are causing widespread depletion of natural resources while generating substantial food subsidies that offer new foraging opportunities for wildlife. These changes in food availability are reshaping ecosystems and influencing individual behaviours and population dynamics of species worldwide. Landfill sites are now recognized as one of the most important predictable anthropogenic food subsidies and are increasingly associated with enhanced fitness, survival, and abundance of opportunistic species. This thesis combines extensive GPS tracking, behavioural video recordings at landfills, and long-term breeding data to explore the drivers and mechanisms underlying changes in the foraging behaviour of the opportunistic white stork (Ciconia ciconia), particularly in the increased use of landfill resources. In the first study, I explore age-related differences in landfill use and demonstrate that adult storks visit landfills considerably more often than juveniles, exhibit higher feeding success, and display greater aggression towards conspecifics. Consequently, juveniles are outcompeted by adults and displaced from accessing these food sources. In further investigation into the ontogeny of landfill use, I reveal that landfills become crucial foraging sites for storks early in life. The increase in this new foraging behaviour is then driven by the development of individual foraging skills during the first few years and refined as individuals mature, resulting in better performance in the use of these resources in adulthood. Finally, when exploring the influence of landfill resources on the breeding performance and population dynamics of storks, I found that breeding near landfills advances the laying dates, positively affecting clutch sizes and fledgling numbers. Proximity to landfills is also decisive for increased fledgling body condition. Consequently, variations in the abundance and distribution of nests further revealed a notable increase in the overall number of nests in just six years, particularly in the areas closer to landfill sites, indicating a dynamic interplay between landfill resources, breeding success, and population dynamics. Overall, this research provides valuable insights into the intricate relationship between anthropogenic food subsidies, foraging behaviour, life traits, and population dynamics of opportunistic bird species. Moreover, it provides a basis for understanding the consequences of anthropogenic food waste on wildlife, guiding future conservation efforts and management of wildlife populations in the context of changing ecosystems.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Environmental Sciences
Depositing User: Chris White
Date Deposited: 03 Jul 2024 11:47
Last Modified: 03 Jul 2024 11:47

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