A DESCRIPTION OF MIXED-SPECIES INSECTIVOROUS BIRD FLOCKS IN WESTERN MEXICO
A DESCRIPTION OF MIXED-SPECIES INSECTIVOROUS BIRD FLOCKS IN WESTERN MEXICO
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作者：
HUTTO, RL
食虫鸟群观察到在所有类型的森林栖息地在非繁殖季节在墨西哥西部。五种生境类型的鸟类种类组成变化显著，且具有可预测性。在低地生境中，平均每群鸟类的物种数为4.7种，而在高地生境中，平均每群鸟类的物种数为18.6种，后者是世界上物种最丰富的鸟类。当地食虫物种的平均比例，参加混合种群是显着更大的高地（61.4%）比低地（24.6%）。在未受干扰的低地和高地栖息地，大约一半的羊群参与者是北温移民，西墨西哥的羊群也是世界上最富移民的。在高地的鸟群中，每个伴随物种的最大个体数通常是2到3个，但通常有6到12个个体属于几个核心物种。 低地落叶林的鸟群似乎缺乏核种。
Insectivorous bird flocks were observed in all types of forested habitats during the nonbreeding season in western Mexico. The species composition of flocks changed markedly and predictably among five categories of habitat type. The average number of species per flock in lowland habitats was 4.7, while a mean of 18.6 species participated in highland flocks, ranking the latter among the species-rich flocks in the world. The mean proportion of the local insectivorous species that participated in mixed-species flocks was significantly greater in the highlands (61.4%) than in the lowlands (24.6%). About half of the flock participants in both undisturbed lowland and highland habitats were north temperature migrants, ranking west Mexican flocks among the most migrant-rich in the world as well. In highland flocks, the maximum number of individuals per attendant species was generally two to three, but there were often six to twelve individuals belonging to each of several nuclear species. The lowland deciduous forest flocks seemed to lack nuclear species.