科研之友
微信
新浪微博
Facebook
分享链接
摘要
Altitudinal migration by birds in the tropics is poorly described and the migratory patterns of many species remain unknown. Stable-isotope analysis may be a suitable method for tracking elevational movements. Globally, stable-hydrogen isotope (delta D, deuterium) values of rainwater show a linear depletion trend with increasing elevation. Birds incorporate local delta D values during tissue synthesis and, if individuals move altitudinally, their tissue delta D should reflect the area where the tissues were grown. We tested the feasibility of this method for tracking elevational movements of birds on the eastern slope of the Ecuadorian Andes by exploring the relationship between elevation, rainwater delta D, and avian tissue delta D. We sampled rainwater as well as the blood and feathers of 122 birds representing 18 species over an elevational gradient (1350-3500 m asl). Bird tissue and rainwater delta D decreased with increasing altitude. delta D feather values showed a weaker relationship with elevation than blood delta D values, reflecting the short-term recent synthesis of blood. Elevation explained little of the variability in feather delta D, which could reflect altitudinal migration. However, we could not reliably identify migrants because of the potential effects of intrannual shifts in rainwater delta D, diet, and molt timing on feather delta D. Rainwater delta D differed from global averages and data available for Ecuador, underlining the importance of local sampling in the year(s) of interest. Our results indicate that altitudinal migrants may be tracked using delta D only at larger scales (> 1000 m) when local variability in tissues driven by molt and diet are understood.
- 出版日期2010-3
