Meeting Abstract

P3.35  Sunday, Jan. 6  Vegetation Density as an Indicator of Wood Thrush Abundance CORNELL, A.E.; Simon Fraser University acornell@sfu.ca

Wood Thrush (Hylocichla mustelina), a neotropical migrant of Eastern North America, have been declining throughout their range since the 1970s. Some suggest that causes may include fragmentation and degradation of breeding habitat, which leads to higher nest predation and brood parasitism rates. Density of vegetation may be an important habitat quality indicator, as Wood Thrush show marked preference for dense understory nest sites. Over the past 21 years the Missouri Ozark Forest Ecosystem Project (MOFEP) has observed a decline in Wood Thrush at control, uneven-aged, and even-aged forest management sites. The decrease could be a related to changes in vegetation density due to harvest of treatment sites; control sites may have decreased understory vegetation density as the forest matures and the canopy closes. This study investigated the abundance of Wood Thrush at varying vegetation densities at two experimental plots with uneven-aged treatment, two with even-aged treatment, and two control plots. The entire 2500 hectare site was surveyed for Wood Thrush using spot maps during eight weeks of the breeding season. A 6” by 8’ density board was used to estimate the density of understory vegetation from the ground up. Vegetation density was found to be positively correlated with Wood Thrush abundance. This evidence suggests that Wood Thrush select territories with higher densities of vegetation for reproduction. If the cause of Wood Thrush decline is the decrease in breeding habitat quality, understanding habitat preferences like vegetation density will be key to their conservation.