Schaub M, Jenni L
Swiss Ornithological Institute, CH-6204 Sempach, Switzerland e-mail:
Oecologia. 2000 Feb;122(3):306-317. doi: 10.1007/s004420050036.
The rate at which migrant birds replenish their energy stores at intermittent stopovers largely determines overall migration speed, the manner in which migration proceeds and success of migration. In this study, data on the fuel deposition rate (FDR) of three long-distance migrants from 17 ringing sites along their autumn migration route were used to examine: (1) effects of endogenous factors on FDR, and (2) how relationships between exogenous factors and FDR affect the organisation of migration. We developed a model to estimate FDR from retrapped birds which takes into account time of day and various other factors which might influence FDR. The two endogenous factors, moult and current energy stores, generally reduced FDR. This may result in lower departure energy loads and more stopovers than expected from optimal migration theory. Differences between species with respect to seasonal, year-to-year and geographical patterns of FDR could be related to differences in availability and predictability of food resources, and help to explain differences in the organisation of migration. A low FDR in northern and central Europe could be related to low, but predictable, food resources and an early departure during moult of the reed warbler (Acrocephalus scirpaceus); FDRs varying between years were related to large spatial and year-to-year variation in the density of the main prey of the sedge warbler (Acrocephalus schoenobaenus); and a high FDR in the garden warbler (Sylvia borin) was related to abundant food resources, due to a switch from a purely invertebrate diet to a mixed diet including fruits which are abundant over large areas of Europe and north Africa. This study demonstrated that the organisation of migration is the outcome of a complex interplay of the seasonal timing of moult, food availability and predictability and a seasonal switch in diet, and can be modified by individual birds in response to a limited amount of time in which to migrate.
候鸟在间歇性中途停留时补充能量储备的速率在很大程度上决定了整体迁徙速度、迁徙的进行方式以及迁徙的成功率。在本研究中，利用了沿着三条长途迁徙鸟类秋季迁徙路线上17个环志地点的燃料沉积率（FDR）数据来研究：（1）内源性因素对FDR的影响，以及（2）外源性因素与FDR之间的关系如何影响迁徙的组织。我们开发了一个模型，用于根据重新捕获的鸟类估计FDR，该模型考虑了一天中的时间以及可能影响FDR的各种其他因素。两个内源性因素，换羽和当前能量储备，通常会降低FDR。这可能导致出发时的能量负荷较低，中途停留次数比最优迁徙理论预期的更多。不同物种在FDR的季节性、年际和地理模式方面的差异可能与食物资源的可获得性和可预测性差异有关，并有助于解释迁徙组织的差异。欧洲北部和中部的低FDR可能与芦苇莺（Acrocephalus scirpaceus）换羽期间食物资源少但可预测以及提前出发有关；FDR在不同年份之间的变化与草甸鹀（Acrocephalus schoenobaenus）主要猎物密度的大空间和年际变化有关；而花园莺（Sylvia borin）的高FDR与丰富的食物资源有关，这是由于从纯无脊椎动物饮食转变为包括水果的混合饮食，水果在欧洲和北非的大片地区都很丰富。这项研究表明，迁徙的组织是换羽的季节性时间、食物可获得性和可预测性以及饮食季节性转变之间复杂相互作用的结果，并且个别鸟类可以根据有限的迁徙时间进行调整。
