Changes in habitat use and resource selection of American White Ibis (Eudocimus albus) along an urbanization gradient in South Florida have consequences for their health

The American White Ibis (Eudocimus albus) is a nomadic wading bird, synonymous with the Everglades, that moves unpredictably between wetlands throughout their lifetime. Within the last two decades, ibis in south Florida are... [ view full abstract ]

The American White Ibis (Eudocimus albus) is a nomadic wading bird, synonymous with the Everglades, that moves unpredictably between wetlands throughout their lifetime. Within the last two decades, ibis in south Florida are increasingly found foraging in high densities in urban areas, and relying on artificial wetlands. This new habitat use aggregates individuals, habituates them to people, exposes them to novel resources (such as low quality anthropogenic food) and encourages contact with atypically encountered species, all of which have direct consequences for their health. Our project is part of a larger effort investigating the health of urbanized white ibises relative to wildland ibis. We are interested in the movement patterns and habitat use of ibises utilizing natural wetlands, agricultural areas, and urban areas both to determine degrees of fidelity to urban habitats and detect seasonal trends in habitat use. We outfitted 32 ibises from Palm Beach and adjacent counties, Florida with EcoTone backpack GPS transmitters recording 6 locations per day. Time spent in urban habitat types, measures of site fidelity, and home range size were calculated. Winter season home ranges of urban birds averaged 2.7 km2, while wildland bird home ranges were up to 2 orders of magnitude larger. In addition urbanized ibises visited fewer locations and thus could be at risk of effects to their health from consuming poor quality food or water, forming dense aggregations, and contacting urban species. Comparatively, individuals spending time in natural and restored wetlands used a greater variety of locations and travel further distances. In contrast to previous VHF radiotelemetry studies, GPS data provides a fine-scale picture of ibis movements along an anthropogenic gradient and will be instrumental in understanding how species change their movement ecology when adapting to urbanization.