The influence of forest harvesting and fire on breeding birds of mature boreal mixedwood forests in northeastern Ontario

In boreal forests, clear-cutting may have a negative influence on forest birds adapted to fire regimes. Using point-counts, I sampled birds in mature post-fire and post-harvest mixedwood stands in northeastern Ontario and examined the relationships between disturbance type and tree age with bird community composition, species richness and abundance. Multivariate analyses showed that post-fire stands had more snags and canopy complexity than post-harvest stands and their bird community was comprised mainly of cavity-nesters and overstory foliage gleaners. In contrast, post-harvest stands had a denser understory and their bird community was comprised of species associated with the shrubs. Guild-level analyses showed that cavity-nesters had a strong negative response to clear-cutting independently of age, correlated with a reduction in the amount of coarse woody debris. These results highlight both the importance of old mixedwood forests for birds, and the need to develop silvicultural methods to better approximate post-fire forest structure.