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836 results on '"MCGRAW, KEVIN J."'

5. Variation in Plumage Coloration of Rosy‐Faced Lovebirds (Agapornis roseicollis): Links to Sex, Age, Nutritional Condition, Viral Infection, and Habitat Urbanization.

Author

McGraw, Kevin J., Hammond, Reilly, Kraberger, Simona, and Varsani, Arvind

Subjects
*PSITTACINE beak & feather disease, *COLOR of birds, *BLOOD sugar, *INTRODUCED species, *INNER cities
Abstract

ABSTRACT Expression of vibrant plumage color plays important communication roles in many avian clades, ranging from penguins to passerines, but comparatively less is known about color signals in parrots (order Psittaciformes). We measured variation in coloration from three plumage patches (red face, blue rump, red tail) in an introduced population of rosy‐faced lovebirds (Agapornis roseicollis) in Phoenix, Arizona, USA and examined color differences between the sexes and ages as well as relationships with several indices of quality, including disease presence/absence (infection with beak and feather disease, Circovirus parrot, and a polyomavirus, Gammapolyomavirus avis), nutritional state (e.g., blood glucose and ketone levels), and habitat type from which birds were captured. We found that different plumage colors were linked to different quality indices: (a) adults had redder faces than juveniles, and birds with brighter faces had lower glucose levels and were less likely to have polyomavirus; (b) males had bluer rumps than females; and (c) birds caught farther from the city had redder and darker tail feathers than those caught closer to the urban center. Our findings reveal diverse information underlying variation in the expression of these disparate, ornate feather traits in an introduced parrot species, and suggest that these condition‐dependent and/or sexually dichromatic features may serve important intraspecific signaling roles (i.e., mediating rival competitions or mate choices). [ABSTRACT FROM AUTHOR]

Published
2024
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6. Correlates of Co-Infection with Coccidiosis and Avian Malaria in House Finches (Haemorhous mexicanus).

Author

de Souza Penha, Victor Aguiar, Manica, Lilian Tonelli, Barrand, Zachary A., Hepp, Crystal M., and McGraw, Kevin J.

Abstract

Pathogens have traditionally been studied in isolation within host systems; yet in natural settings they frequently coexist. This raises questions about the dynamics of co-infections and how host lifehistory traits might predict co-infection versus single infection. To address these questions, we investigated the presence of two parasites, a gut parasite (Isospora coccidians) and a blood parasite (Plasmodium spp.), in House Finches (Haemorhous mexicanus), a common passerine bird in North America. We then correlated these parasitic infections with various health and condition metrics, including hematological parameters, plasma carotenoids, lipid-soluble vitamins, blood glucose concentration, body condition, and prior disease history. Our study, based on 48 birds captured in Tempe, Arizona, US, in October 2021, revealed that co-infected birds exhibited elevated circulating lutein levels and a higher heterophil: lymphocyte ratio (H/L ratio) compared to those solely infected with coccidia Isospora spp. This suggests that co-infected birds experience heightened stress and may use lutein to bolster immunity against both pathogens, and that there are potentially toxic effects of lutein in co-infected birds compared to those infected solely with coccidia Isospora sp. Our findings underscore the synergistic impact of coparasitism, emphasizing the need for more co-infection studies to enhance our understanding of disease dynamics in nature, as well as its implications for wildlife health and conservation efforts. [ABSTRACT FROM AUTHOR]

Published
2024
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