Characterizing Northern Saw-Whet Owl (Aegolius acadicus) Winter Habitats in South-Central Indiana

摘要: Northern Saw-whet Owl (Aegolius acadicus) winter habitat in south-central Indiana was assessed during two winters (2003/2004 & 2004/2005). Differences between locally occupied and unoccupied were examined, compared to other regions. Using audio surveys active voice detection, 40 locations sampled the first winter, 45 second 35 both 50 total. The presence of Owls strongly related understory transparency, agreeing with previous studies Maryland Michigan showing a correlation dense vertical structure. However, there no evidence strong either evergreen canopy cover, stem density or mid-canopy gap, contradicting results from Minnesota, Michigan, though minimum 40% cover sites. lack consistency among indicates regional variability structure sites by Owls, but dependable reliance on cover. Historic records show that Saw­ whet occasionally breed northern Indiana, migrant popu­ lations spend across state (Cannings 1993). Christmas Bird Count have also consistently (since 1985) documented wintering Indiana. Between fall spring migration events, potential forest surveyed for characterize habitats 2003/2004 2004/2005. undergo an annual movement their primary breeding range boreal forests along U.S.-Canada border points as far south Gulf Coast (Weir et al. 1980; Cannings 1993; Swengel 1997). This partial has high degree due "irruptive" years when number migrating can be ten times higher than longterm average Whalen Watts 2002). Breeding are usu­ ally found coniferous mixed coniferous­ deciduous well-developed middle trees Wintering appear rely vegetation