Determinants of Wetland- Bird Community Composition in Agricultural Marshes of the Northern Prairie and Parkland Region

Abstract

Wetland losses in the Northern Prairie and Parkland Region are largely attributed to agriculture. Since land use is known to influence bird habitat selection, bird community composition is likely sensitive to the extent of neighboring agricultural activity. We determined local and landscape habitat variables predictive of wetland-dependent avian assemblage occurrence in southern Alberta. We: 1) identified distinct bird assemblages with a cluster analysis, 2) identified species indicative of these assemblages using an indicator species analysis, and 3) predicted bird assemblage occurrence in wetlands using a classification and regression tree. Wetland-dependent birds formed distinct avian assemblages that were primarily differentiated by region and local-level habitat characteristics like wetland size, depth, or vegetation cover. Generally, however, wetland-dependent bird assemblages were surprisingly insensitive to surrounding landscape composition. The extent of agricultural activity in the surrounding landscape was weakly predictive of avian assemblages in wetlands in the Grassland Natural Region, with edge-nesting birds being excluded from wetlands with >42% agricultural land cover in the surrounding landscape.