Avian admission trends at three wildlife rehabilitation facilities in the United States

Wildlife rehabilitators play a crucial role in monitoring wildlife health and are often the first to engage the public when they encounter injured or orphaned wildlife. Due to the vast number of animals rehabilitators treat annually, rehabilitation records serve as a valuable and cost-effective data source for monitoring wildlife population and health trends. This study explores avian admission trends across three wildlife rehabilitation facilities in the US from 2015 to 2023. Our goal was to explore whether trends in the number of birds entering wildlife rehabilitation facilities reflected events on the landscape, including the coronavirus disease 2019 (COVID-19) pandemic and the highly pathogenic avian influenza (HPAI) H5N1 outbreak. Digitized records of 43 297 native wild birds were accessed through the Wildlife Rehabilitation Medical Database (WRMD). Time series analyses showed an increasing trend in the number of birds admitted to all facilities from 2015 to 2019, followed by a decline in admissions, particularly amongst raptors, waterfowl and passerines, post-2021 in all three rehabilitation facilities. Admission data for all facilities also showed a strong seasonal pattern, with yearly peaks between May and July. Given the limitations of a retrospective analysis of sole intake numbers, we were unable to link these trends to any specific event confidently; nevertheless, this study demonstrates that rehabilitation data hold the potential to provide insight into avian population trends when interpreted within the broader context of disease dynamics, environmental change and human activity.