Avian recolonization of eastern Canadian bogs after peat mining

To evaluate the potential of bog ecosystems to recover following peat mining, we compared bird species richness, abundance, and assemblages and vegetation among naturally revegetated and undisturbed bog sites in southeastern Quebec. Based on mining history, we selected 28 sites (12 natural, 9 abandoned after blockcut extraction, and 7 abandoned after vacuum extraction) in 15 bogs. We estimated percent cover for six vegetation strata in 106 plots with 100 m radius, on which bird point counts were conducted in 1993 and 1996. Vegetation structure differed significantly between natural, post-blockcut and post-vacuum sites. While vegetation cover was almost complete in natural sites, abandoned sites, especially post vacuum, were less vegetated, even after 20 years. Bird species richness and abundance were similar in natural and post-blockcut sites and both were higher than in post-vacuum sites. Ten of the 28 species studied in detail responded to site perturbation. Among them, the Palm Warbler was most closely associated with natural sites. Bird communities were closely associated with vegetation structure. Communities of post-blockcut sites were more similar to those of natural bogs than were bird communities of post-vacuum sites. Since the blockcut method of peat mining is no longer economically feasible, we conclude that bog habitat restoration should be accompanied by a preservation "safety net" area to counteract the lasting effect of vacuum peat mining on bird species assemblages.