Habitat Use by Sedge Wrens in Southern Québec

Abstract

We studied Sedge Wrens (Cistothorus platensis) along transects in fens of Lake Saint-François National Wildlife Area (NWA) to identify key habitat components associated with breeding territories. Stations (0.13-ha circles centered on clusters of locations) occupied by Sedge Wrens had higher lateral visibility (lower vertical cover) and lower shrub cover (lower tall shrub density, fewer shrub stands, reduced length of stands along transects, and greater distance to the nearest shrub) compared to unoccupied stations. Mean lateral visibility was low (<25%) below 100 cm and did not differ between stations, and visibility was greater for higher height classes at stations occupied by wrens. The relative cover of dominant plant species (Carex lacustris, C. aquatilis, Lythrum salicaria, Thelypteris palustris, Calamagrostis canadensis) did not vary between stations occupied or unoccupied by Sedge Wrens. The habitat structure at the territory scale influenced Sedge Wren occupancy as birds preferred stations with lower shrub cover and higher lateral visibility. We found an average of 0.21 Sedge Wrens/ha along transects, similar to densities reported in some regions of the midwestern USA.