Beaver activity and red squirrel presence predict bird assemblages in boreal Canada

Lay Summary center dot Studies of bird assemblages and their responses to local and landscape factors in boreal landscapes can inform wetland conservation. center dot The aim of our study was to assess how bird occupancy differed between two major pond types and responded to habitat, landscape factors, and potential predators in boreal assemblages in northeastern Canada. center dot We detected 96 species using automated recorders deployed at 50 ponds in 2018 and 2019. center dot Species richness was higher in beaver ponds than peatland ponds. Species richness was lower in the presence of red squirrel, a potential nest predator, and decreased with increasing latitude. center dot Our results highlight the importance of beavers and factors associated with red squirrel presence in shaping bird assemblages in boreal landscapes. Wetlands and predation in boreal ecosystems play essential roles throughout the breeding season for bird assemblages. We found a positive association of beaver activity and a negative influence of American red squirrels (Tamiasciurus hudsonicus) on bird assemblages. We used a multispecies hierarchical model to investigate whether bird communities differ between two major wetland habitats in boreal Canada: beaver ponds and peatland ponds. In addition to including variables such as forest cover and latitude, we adopted a structural equation model approach to estimate the occupancy of American red squirrels and its potential influence on bird communities. Using automated recording stations deployed at 50 ponds, we detected 96 bird species in 2018 and 2019. Bird species were grouped into four taxonomic guilds according to their habitat successional requirements: early successional species, late successional species, generalists, and wetland species. Beaver ponds harbored higher species richness, a pattern driven primarily by early successional species. The occupancy of almost a quarter of the species was lower in the presence of red squirrels. Late successional species responded positively to the cover of forest surrounding the pond. Our results highlight the value of considering acoustic data of red squirrels to quantify habitat quality in boreal forests. We conclude that beaver activity shapes bird assemblages through modification of their habitat, and that some bird guilds are associated negatively with the presence of American red squirrels.