An evaluation of Canada's Permanent Cover Program: Habitat for grassland birds?

In the early 1990s Agriculture Canada's Permanent Cover Program (PCP) converted over 445,000 ha of cropland to perennial vegetative cover. The wildlife benefits of the PCP have not been the subject of previous research. We conducted grassland bird surveys on 629 PCP sites and 564 cropland sites across Alberta, Saskatchewan, and Manitoba between 25 May and 3 July 1998. PCP sites showed higher avian species richness than cropland, and nine of 10 commonly detected grassland bird species occurred at higher frequencies in PCP than cropland. PCP sites were characterized by taller, denser vegetation and less bare ground than cropland sites. Hayed and grazed PCP sites differed significantly in their vegetative structure and avian community composition, but did not differ in species richness or evenness. Mean bird species richness at both cropland and PCP sites was significantly lower in the aspen parkland ecoregion than in the mixed and moist-mixed grassland ecoregions. Logistic regression identified 18 geographic and vegetative variables that significantly influenced the occurrence of individual species, but models for only two species predicted both presence and absence with greater than 50% accuracy. Avian productivity on PCP lands must be determined to appraise definitively the quality of this habitat for grassland birds.