Peregrine Power (United States)

Moult, breeding, and migration are the three major life‐history events in the annual cycle of birds. All are energetically demanding processes that rarely overlap. In large raptors such as the Egyptian vulture Neophron percnopterus , completing a full moult may take more than one year, requiring birds to balance this process with other life‐cycle events. We analysed 740 moult cards from across the species' distribution, including migratory, sedentary and mixed subpopulations, to test predictions about trade‐offs between the physiological demands of migration and moult. Juveniles began moulting in January–February of their second calendar year and continued ‘year‐round' until their fifth calendar year. Adults, however, suspended moult from the months preceding spring migration until the late breeding phase. Subadults from the Canary Islands started moulting earlier and completed it faster than those from western Europe, while adults from western Europe initiated moult later than adults from the Canary Islands, India, and Oman. Sedentary subpopulations, particularly that from the Canary Islands, showed a greater moult extent and replaced more primaries annually than migratory and mixed subpopulations, whereas the wintering subpopulation of southwestern Spain (Extremadura) exhibited the smallest moult extent. Moult symmetry decreased from the second plumage onwards and differed between the Canary Islands and Oman subpopulations. Geographic differences in moulting patterns likely arise from population‐specific life‐history trade‐offs, reflecting local adaptations or responses to environmental constraints. These patterns highlight the influence of migratory strategy on moult progression and suggest that sedentary lifestyles may allow more extensive feather renewal in long‐lived raptors.

ABSTRACT After rebounding from near extirpation during the organochlorine era, breeding Peregrine Falcons ( Falco peregrinus ) in California are again facing adversity, this time consistent with an outbreak of a highly pathogenic avian influenza. Following the first detection of the H5N1 variant clade 2.3.4.4b virus in California wild birds in July 2022, we assembled data from long-term monitoring (2000–2025) of peregrine breeding territory occupancy in the broad vicinity of San Francisco Bay to examine possible impacts on falcon populations. Prior to the outbreak, 47 focal breeding territories had shown nearly complete occupancy by pairs (98.5% of 390 site-years), with very few vacancies, single birds in attendance, or subadult pair members. Within 8 mo of the outbreak, occupancy had dropped to 65.1%, and 2 yrs later (2025), only 36.2% of sites remained occupied. An uptick in site-occupancy by single birds also occurred after the outbreak, but it is unclear whether these were survivors or floaters attempting to fill vacant territories where both pair members had perished. The high vacancy rates signaled an impact upon floaters (nonbreeding adults) that normally buffer breeding site-occupancy in healthy peregrine populations. From October 2022 through November 2025, 17 peregrine fatalities were diagnosed with H5N1 within the counties comprising our study area. Evidence that H5N1 caused these territory vacancies includes, (1) the striking temporal coincidence of occupancy loss with the outbreak, and (2) the lethality of the virus to peregrines and its confirmed presence in peregrine prey in our study area. Our study reaffirms the value of long-term territory occupancy monitoring in this sentinel species.

Trait datasets play a crucial role in advancing ecological, biogeographical and evolutionary studies and in prioritizing global conservation efforts. Birds are the best-known major group of organisms and comprise excellent environmental indicators. With their diverse traits, birds offer valuable insights into the provisioning of critical ecological functions and how animals adapt to global change. BIRDBASE is a global avian trait dataset that provides an up-to-date compilation of ecological traits for all birds. With 78 traits from 11,589 bird species in 254 families, and data on 6%-16% more species than the previous avian trait datasets, BIRDBASE includes all the bird species recognized by the four major avian taxonomies. BIRDBASE is also the first avian trait dataset that covers all the species in AviList, the new unified global avian checklist. As the most comprehensive avian trait dataset, BIRDBASE will enable new meta-analyses in ornithology, conservation biology and macroecology, expand our ability to understand the origins and maintenance of biodiversity, help quantify avian responses to global change, and inform international conservation efforts.

Abstract Management of emerging pathogen and parasite threats could provide cost‐effective compensatory mitigation options for protected species, such as golden eagles ( Aquila chrysaetos ). Golden eagle nestlings are vulnerable to infestations of poultry bugs ( Haematosiphon inodorus ), a blood‐sucking ectoparasite that lives in nest material and trichomonosis, a highly lethal disease caused by the protozoan Trichomonas spp. We aimed to develop effective treatment protocols for poultry bugs and trichomonosis and project whether nestling parasite and disease management would have population‐level effects in this long‐lived apex predator. We collected pre‐treatment data on poultry bug loads in eagle nests; then, we applied 1 of 3 experimental parasite treatments to empty eagle nests in late summer months: a combination of permethrin and diatomaceous earth, diatomaceous earth‐only or water—a control, and measured effects on poultry bugs and nestlings the following year. During nestling exams, we treated trichomonosis‐infected nestlings with an anti‐protozoan drug. Then, we projected the effects of treatments on population growth using simulation models. The permethrin and diatomaceous earth nest treatment significantly reduced poultry bug densities in the subsequent breeding season and improved nestling health and survival. Nestlings had significantly greater haematocrit; female nestlings had greater mass, and, on average, 0.70 more nestlings successfully survived to fledge compared with control‐ and diatomaceous earth‐only‐treated nests. Ten eagle nestlings from 27 nests that likely would have died from trichomonosis lived to fledge from the nest after treatment. Over 2 years, we estimate saving 17.5 nestlings, which equates to 10.2 adult eagles. We projected that treatments of poultry bugs and trichomonosis could increase local eagle population growth rates by 8% and 4%, respectively. Synthesis and applications . For sensitive or at‐risk bird species, treating parasites and disease can improve nest productivity and support population growth, making it a valuable conservation tool. In areas with high concentrations of poultry bugs or where eagles consume avian vectors of Trichomonas spp., pathogen and parasite treatments may serve as an effective mitigation strategy with population‐level benefits for eagles.

Abstract Bulk stable isotope analysis of carbon and nitrogen is commonly used to assess trophic relationships. However, compound‐specific stable isotope analysis of individual amino acids may be a more accurate approach for resolving food web structure. Nevertheless, recent studies suggest amino acid‐specific nitrogen trophic discrimination factors (TDFs) can vary depending on the type of nitrogenous waste produced and the quality of the diet, potentially limiting inference. We compared the ability to discriminate between primary and secondary consumers using bulk and compound‐specific methods in an Arctic tundra ecosystem. Specifically, we determined bulk δ 13 C and δ 15 N values, as well as amino acid‐specific δ 15 N values, for red blood cells from nestling golden eagles ( Aquila chrysaetos ), rough‐legged hawks ( Buteo lagopus ), and gyrfalcons ( Falco rusticolus ), as well as for muscle samples from common prey species. We subsequently used high‐precision diet estimates from nest cameras to estimate TDFs for gyrfalcon nestlings and compare these against TDFs for other taxa from the literature. Although bulk δ 15 N values of secondary consumers were enriched relative to primary consumers, overlap occurred across groups, and greater separation was apparent using δ 15 N of amino acids. Comparing red blood cell δ 15 N values to prey muscle δ 15 N values, bulk TDFs and compound‐specific TDFs for trophic amino acids were lower than values from the literature that have typically been used to estimate trophic position. Amino acid‐specific TDFs for raptor nestlings may be particularly low due to their rapid growth, consumption of high‐quality protein, and excretion of nitrogenous wastes as uric acid, which have previously been identified as factors influencing isotopic discrimination. Consistent with recent studies, our findings indicate that the use of ‘universal’ TDF Glu‐Phe values will result in an underestimate of nestling trophic level, and more work is needed to establish appropriate TDFs that reflect the physiology and life‐history stage of the consumer.

Summary Andean Condor Vultur gryphus populations are particularly low in the northern Andes. The species is considered nearly eradicated from Venezuela and listed as “Endangered” in Ecuador and “Critically Endangered” in Colombia. Even though it is severely endangered, the size of the Colombian condor population remains unknown. Using a citizen science-based approach, we conducted the first Andean Condor count for Colombia with the help of 207 observers at 84 simultaneous observation points. We used N-mixture models for spatially replicated counts to estimate the condor population. The total number of condors recorded simultaneously was 63 individuals, and we estimated a population size of 175–269 individuals using a maximum likelihood approach and 165–222 and 172–229 for the two best models using the Bayesian approach. Adults were observed more frequently than juveniles (1:0.43), a common pattern among raptors related to the higher mortality rates of immature birds, which is a prominent conservation concern due to the status of the species and the threats it currently faces throughout the northern Andes. Our citizen science-based study made it possible to gather, for the first time in Colombia, consolidated information on the status of the Andean Condor population using a standardised methodology to provide a reference for future counts and conservation actions, both at the national level and throughout the geographical range of the species.

Abstract Forest management is an important component of global change as more than half of the world's forests are managed for human use. Although the effect of forest management on taxonomic diversity is well‐studied, we do not fully understand its impact on functional diversity. Understanding this is important to better predict how ecosystem processes will respond to global change scenarios and to implement efficient conservation actions. We conducted two large‐scale (~81 800 km2) research projects over 4 years in temperate forests of the northeastern USA to investigate how the functional structure of bird and mammal communities are affected by forest disturbance. We surveyed 85 bird species distributed in 115 sites using point counts, and 14 mammal species across 197 sites using camera traps. For each species, we selected functional traits that summarize key features of their biology, and for each site, we collected data on the level of forest disturbance based on forest loss events. We found that functional richness increased with forest disturbance for mammals but not for birds. Our results also showed that niche breadth (diet), morphological (body mass and wing length), and physiological (litter size) factors were the main determinants of the functional structure of both groups. These findings emphasize the complexity of making predictions about responses to forest management given the heavy dependence on the context and taxa studied. Overall we observed a limited response of functional diversity to forest management, which might indicate that the environmental changes generated by forest management in this region are less extreme than deforestation or conversion of natural forest to plantations of exotic species. Nonetheless, our results underscore the importance of investigating the effects of forestry on individual traits to develop strategies for managing for ecosystem functions.