Temporal and Spatial Variations of Bird Assemblage in Taroko National Park
Date Issued
2008
Date
2008
Author(s)
Peng, Chun-Yi
Abstract
Topographic features and weather patterns in Taroko Gorge are different from the western slope of Central Mountains, resulting in special bird assemblage in Taroko. To investigate the differences between Taroko and the western slope of Central Mountains, I studied the bird assemblage in Taroko and focused on: (1) avian distribution along elevation gradient (2) patterns of seasonal distribution changes (3) distribution and composition of guilds. Seventy-four sampling sites along Central Cross-Island Highway were inventoried twice a month from April 2006 to March 2007. I compared the distributions of 24 species of birds in breeding and non-breeding season. Moreover, I viewed the relationship between species richness and elevation gradient and studied the guild distribution and composition along elevation gradient. I recorded 31 different genuses, totaling 99 species, and generalized seven patterns of seasonal distribution changes. After comparing it with the breeding season, the distribution pattern changes were: (1 ) lower limit moved downward. (2) upper limit moved downward. (3) both upper and lower limit moved downward. (4) both upper and lower limit expanded. (5) upper limit moveed upward. (6) both upper and lower limit moveed upward. (7) both upper and lower limit remained the same. Species richness show a hump-shaped relationship along elevation gradient. With regards to the guild during breeding season, carnivore distribution is in the low altitude(0–1500m), bole insectivores and ground insectivores are found in mid altitude(1500–2500m), tree insectivores distribute in mid and high altitude(>2500m), ground omnivores distribute in high altitude, and other guilds distribute evenly across the altitudinal gradient. . In non-breeding season, all insectivores’ distributions move downward, omnivores and carnivores do not change their distribution, and tree herbivores only appear in this season. Composition of guild along elevation gradient in breeding season shows that in low altitude the dominant guild are tree omnivores and fly-catch insectivores, in mid altitude the dominant guilds are tree omnivores and tree insectivores, and in high altitude dominant guilds are shrub insectivores and tree insectivores. During the non-breeding season tree herbivores replace part of tree omnivores and become dominant guild, all species of insectivores decrease their weight in their original altitude and increase their weight in lower altitude, and in high altitude ground omnivores replace shrub insectivores and become dominant guild. We concluded that the distributions and heights where the bird moves in between seasons in Taroko are different from the patterns on the western slope of Central Mountain and result from the difference of topography and weather patterns. Different movement patterns from the past research were due to resource distribution, different research methods, and different research boundaries. Understanding the background of study site helps us better understand the factors affecting bird distribution, and the full elevation gradient research can clearly describe the bird assemblage.
Subjects
bird assemblage
guild
elevation gradient
seasonal changes
Taroko
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