Department of Zoology, University of Guelph, Guelph, Ontario, NIG 2W1, Canada.
Trends Ecol Evol. 1988 Sep;3(9):237-41. doi: 10.1016/0169-5347(88)90166-8.
Many populations of large herbivores migrate seasonally between discrete home ranges. Current evidence suggests that migration is generally selected for as a means of enhancing access to high quality food and/or reducing the risk of predation. The relative importance of these alternative selection pressures should depend on the demographic circumstances facing a given population. Seasonal migration also has important implications for the structure and dynamics of large herbivore communities. Migrants should tend to be regulated by food availability, while residents should tend to be regulated by predators As a result, migrants should often outnumber residents by a considerable margin - a pattern seen in several tropical and temperate ecosystems. Differences in the mode of regulation could also imply that competition for resources will be weak in purely resident assemblages, but strong in communities dominated by migrants. Continual grazing by resident herbivores can sometimes lead to degeneration of vegetation, while systems supporting migrants are apparently more resilient. This implies that migration can have an important impact on the long-term persistence of plant-herbivore systems, particularly in areas with slow rates of vegetation regeneration.
许多大型食草动物种群在离散的家园之间季节性迁徙。目前的证据表明，迁徙通常是为了获得高质量的食物和/或降低被捕食的风险而被选择的。这些替代选择压力的相对重要性应取决于特定种群所面临的人口统计学情况。季节性迁徙对大型食草动物群落的结构和动态也有重要影响。迁徙者往往受到食物供应的调节，而居民则往往受到捕食者的调节。因此，迁徙者的数量通常会大大超过居民——这种模式在几个热带和温带生态系统中都有出现。调节方式的差异也可能意味着，在纯粹的居民组合中，资源竞争将较弱，但在以迁徙者为主导的社区中，竞争将很强。居民食草动物的持续放牧有时会导致植被退化，而支持迁徙者的系统显然更具弹性。这意味着，迁徙可能对植物-食草动物系统的长期生存产生重要影响，特别是在植被再生速度较慢的地区。
