PARENT SESSION
Oral Session #64: Avian Ecology. Presiding: P. Warren.
Thursday, August 9, 2001. 8:00 AM to 12:00 PM. Hall of Ideas I.
Territorial responses of riparian forest birds to width of watercourses.
GROOM, JEREMIAH1, GRUBB, THOMAS1, 1
ABSTRACT- Habitat fragmentation has been implicated in the decline of Neotropical bird species. Conservation of riparian habitats is an important measure because these habitats may support higher densities of declining Neotropical migrant species than do other habitats. We examined the conditions under which, in a fragmented landscape, a body of water may serve as a territory barrier for breeding birds. We performed a song playback experiment from 31 May-30 June 2000 along waterways in central Ohio, attempting to determine the extent to which individual birds cross bodies of water and incorporate riparian areas on both sides into one territory. Red-eyed vireo (Vireo olivaceus) and eastern wood-pewee (Contopus virens) songs were broadcast across bodies of water, eliciting responses from singing conspecifics. Logistic regression indicated that water gap width was negatively associated with the probability of eastern wood-pewees crossing. Red-eyed vireos demonstrated no such trend. However, the post-crossing strength of red-eyed vireo vocal response was inversely proportional to the width of waterway. These results suggest that water bodies less than 100 m wide may not hinder all species from crossing but may still curtail territorial responses. Therefore, crossing a habitat gap in response to playback may not necessarily represent a territorial response. Riparian habitat conservation plans should consider the impact and importance of waterway and habitat corridor width on territory quality for Neotropical migrant species.
KEY WORDS: gap-crossing, territory, playback, riparian