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

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.