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Ectoparasite loads of birds may be governed, in part, by the climatic characteristics of their environment. We surveyed live-trapped American Kestrels (Falco sparverius caribaearum) for lice and other ectoparasites on the humid subtropical island of Puerto Rico during March–May 2024. The main goal was to compare the prevalence and abundance of lice on kestrels in Puerto Rico to recently published data on the lice of kestrels 1000 km away in the Bahamas, and to the lice of kestrels in an arid region of the western US (Utah). A brief general inspection of the plumage of 39 captured birds was followed by careful examination of the underside of wing primary feathers under a dissecting microscope. Two species of lice were collected, Colpocephalum subzerafae and Degeeriella carruthi, neither previously recorded from kestrels in Puerto Rico. The same two species are present on kestrels in the Bahamas. The prevalence and abundance of lice on kestrels in Puerto Rico and the Bahamas were similar, while being much greater than the prevalence and abundance of lice on kestrels in arid Utah, US. We also collected two species of hippoboscid flies (Diptera: Hippoboscidae): Microlynchia pusilla, not previously recorded on the American Kestrel, and Ornithoctona erythrocephala. These flies, as well as the lice, might affect the health of kestrels both directly, e.g., causing anemia by feeding on blood, and indirectly by vectoring endoparasites. [ABSTRACT FROM AUTHOR]

Environmental factors such as temperature and humidity influence the distribution of free‐living organisms. As climates change, the distributions of these organisms change along with their associated parasites, mutualists and commensals. Less studied, however, is the possibility that environmental conditions may directly influence the distribution of these symbionts even if the hosts are able to persist in altered environments. Here, we investigate the diversity of parasitic lice (Insecta: Phthiraptera) on birds in arid Utah compared to the humid Bahamas. We quantified the parasite loads of 500 birds. We found that the prevalence, abundance and richness of lice was considerably lower among birds in Utah, compared to the Bahamas, despite sampling greater host taxonomic richness in Utah. Our data suggest that as climates change, birds in arid regions will have less diverse louse communities over time, potentially relieving birds of some of the cost of controlling these ectoparasites. Conversely, birds in more humid regions will see an increase in louse diversity, which may require them to invest more time and energy in anti‐parasite defense. Additional research with other ectoparasites of birds and mammals across different environmental conditions is needed to more fully understand how climate change may reshape parasite communities, and how these changes could influence their hosts. [ABSTRACT FROM AUTHOR]

Birds have a diverse community of “permanent” arthropods that complete their entire life cycle on the body of the host. Because some of these arthropods are parasites that reduce host fitness, birds control them by grooming, which consists of preening with the beak and scratching with the feet. Although preening is the primary component of grooming, scratching is essential for controlling arthropods on the head and neck, which cannot be preened. Several unrelated groups of birds have evolved comb-like pectinate claws on the middle toenail of each foot. We tested the role of these claws in the control of arthropods by experimentally removing teeth from the claws of captive western cattle egrets (Bubulcus ibis) infested with chewing lice (Insecta: Phthiraptera), feather mites (Acari: Sarcoptiformes), and nasal mites (Acari: Mesostigmata). After a period of 4 mo, we compared the abundance of arthropods on experimental birds to that of control birds with intact teeth. We used video to quantify the grooming rates of the captive birds, which groomed twice as much as wild birds. Experimental and control birds did not differ significantly in grooming time. Both groups virtually eradicated the chewing lice, but not feather mites or nasal mites. We found no support for the hypothesis that pectinate claws increase the efficiency of arthropod control by grooming. Experiments with wild birds are needed to test the hypothesis further under conditions in which birds devote less time to grooming. [ABSTRACT FROM AUTHOR]