Marra Peter P, Holberton Rebecca L
Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA e-mail:
Department of Biology, University of Mississippi, University, MS 38677, USA, , , , , , US.
Oecologia. 1998 Aug;116(1-2):284-292. doi: 10.1007/s004420050590.
During the non-breeding season, many species of territorial migratory birds exhibit a non-random pattern of habitat distribution, with males and females occupying different habitats. In this study, we examined possible physiological consequences arising from such habitat segregation in one migrant passerine species, the American redstart (Setophaga ruticilla), on its non-breeding grounds in Jamaica, West Indies. For 2 years, we measured concentrations of corticosterone, at the time of capture (baseline) and 30 min after capture (profile of acute corticosterone secretion), in redstarts in two distinct habitats, one occupied predominately by males and one mostly by females. All redstarts in both habitat types exhibited similar concentrations of baseline corticosterone levels in fall (October), whereas in spring (March-April), redstarts in female-biased habitat exhibited significantly higher baseline levels regardless of age or sex. In fall, all individuals in both habitats exhibited significant increases in corticosterone concentration with capture and handling, but in spring only redstarts (both sexes) in male-biased habitat continued to exhibit acute corticosterone secretion. Redstarts in female-biased habitat had elevated baseline corticosterone levels and reduced acute corticosterone secretion. In spring, baseline corticosterone concentration was negatively correlated with body mass, suggesting muscle catabolism associated with high corticosterone concentrations or possibly that birds are leaner as a result of increased foraging effort. These results indicate that redstarts (primarily females) in female-biased habitats suffered a decline in physiological condition, which could in turn influence their departure schedules, migration patterns and even their condition and arrival schedules on the breeding grounds. Thus, segregation of populations into habitats of different quality during the non-breeding period may have ramifications throughout the annual cycle of such migratory species. Furthermore, these results show the usefulness of plasma corticosterone levels as indicators of physiological condition and thus habitat quality for birds during the non-breeding period.
在非繁殖季节，许多具有领地意识的候鸟呈现出非随机的栖息地分布模式，雄性和雌性占据不同的栖息地。在本研究中，我们调查了一种候鸟——美洲红尾鸲（Setophaga ruticilla）在西印度群岛牙买加的非繁殖地，因这种栖息地隔离可能产生的生理后果。连续两年，我们测量了处于两种不同栖息地的美洲红尾鸲在捕获时（基线）和捕获后30分钟（急性皮质酮分泌曲线）的皮质酮浓度，其中一种栖息地主要由雄性占据，另一种主要由雌性占据。两种栖息地类型中的所有美洲红尾鸲在秋季（10月）的基线皮质酮水平浓度相似，而在春季（3月至4月），雌性占主导的栖息地中的美洲红尾鸲，无论年龄或性别，其基线水平都显著更高。在秋季，两种栖息地中的所有个体在捕获和处理后皮质酮浓度都显著增加，但在春季，只有雄性占主导的栖息地中的美洲红尾鸲（无论雌雄）继续表现出急性皮质酮分泌。雌性占主导的栖息地中的美洲红尾鸲基线皮质酮水平升高，急性皮质酮分泌减少。在春季，基线皮质酮浓度与体重呈负相关，这表明高皮质酮浓度与肌肉分解代谢有关，或者可能是由于觅食努力增加导致鸟类变瘦。这些结果表明，雌性占主导的栖息地中的美洲红尾鸲（主要是雌性）生理状况下降，这反过来可能会影响它们的出发时间、迁徙模式，甚至它们在繁殖地的状况和到达时间。因此，在非繁殖期将种群隔离到不同质量的栖息地可能会对这类迁徙物种的全年周期产生影响。此外，这些结果表明血浆皮质酮水平作为鸟类在非繁殖期生理状况及栖息地质量指标的有用性。
