Influence of Radiotransmitters on Fecal Glucocorticoid Levels of Free-Ranging Male American Kestrels |
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Authors: | RICARDO JOSÉ GARCIA PEREIA MARCO ANTONIO MONTEIRO GRANZINOLLI FÁBIO MONTEIRO DE BARROS JOSÉ MAURÍCIO BARBANTI DUARTE |
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Affiliation: | 1. Laboratório de Ecologia de Aves, Departamento de Ecologia, Instituto de Biociências — USP, São Paulo, SP 05508-900, Brazil;2. Núcleo de Pesquisa e Conservação de Cervídeos, Faculdade de Ciências Agrárias e Veterinárias — UNESP, Jaboticabal, SP 14884-900, Brazil |
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Abstract: | ABSTRACT Although radiotelemetry is considered a valuable technique for ornithological field studies, several assumptions have been made about the impact that transmitters may have on the estimation of behavioral, ecological, and reproductive parameters. To assess the potential effects of backpack radiotransmitters, we captured and assigned 8 male American kestrels (Falco sparverius) into 2 groups: radiotagged (n = 6) and control individuals (leg-banded, n = 2). Thereafter, we collected feces approximately 2 hours after capture (day −1), and subsequently during days 0 (releasing day), 4, 7, 15, 30, 40, and 55. Prior to fecal analysis, we validated the corticosterone enzyme immunoassay using standard procedures (e.g., parallelism, dose-response curve), and we confirmed physiological significance of fecal glucocorticoid metabolites through adrenocorticotropin challenge, which induced an increase of 4-fold (446.10 ± 60.73 ng/g) above baseline (114.27 ± 15.23 ng/g) within 4 hours (P < 0.001). Both groups exhibited a significant increase in fecal glucocorticoids during day 0 (P < 0.001), but concentrations returned to preattachment values within 4 days. Fecal glucocorticoid concentrations did not differ between samples of radiotagged and leg-banded kestrels (P > 0.05). In spite of the small number of monitored subjects, these findings suggested that radiotransmitters did not affect adrenocortical activity in these male American kestrels. |
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Keywords: | American kestrel Falco sparverius fecal glucocorticoids radiotelemetry raptors southeast Brazil stress transmitter attachment |
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