Distribution patterns of migrant and resident birds in successional forests of the Yucatan peninsula, Mexico

Increasing human activity in the Yucatan peninsula has led to declines in o lder stages of successional forest, threatening regional habitat diversity. To determine potential effects of this habitat loss on the region's avifau na, we examined the relative use of different forest stages by resident and migrant birds during the nonbreeding season. We used the fixed width trans ect method to compare the distribution, abundance, and diversity of forest birds in early (five to ten years old), mid (15-25 years), and late (> 50 y ears) successional forests in the stare of Campeche, Mexico, in the south-c entral parr of the peninsula. All stages of successional forest: had highly similar bird assemblages and did nor differ in bird abundance or diversity Both migrant and resident birds occurred across the successional gradient. The majority of habitat specialists, however, were resident birds restrict ed to late-successional forest, indicating that early secondary growth may not be suitable for all species. Furthermore, resident birds that typically participate in mixed-species hocks attained their greatest densities in th e oldest forest habitat. Rapid recovery of pre-disturbance physiognomic fea tures, in addition to high levels of habitat connectivity in the region, ma y contribute to similar bird communities across a range of successional sta ges. The high degree of edge characterizing much of the forest mosaic also may allow birds access to different seral stages. Loss of late-successional forest, however, is likely to adversely affect the subset of resident avif auna that depends on unique features of mature habitat such as snags, large trees, and climatic buffering. Conservation efforts in Campeche should foc us on the specialized requirements of the most habitat-restricted species w hile preserving the current landscape mosaic characteristic of the small-sc ale shifting cultivation system.