Exploring forest bird diversity in epiphyte rich temperate deciduous forests : a case study of Söderåsen National Park

Sammanfattning

In this study I investigated the diversity of forest birds in relation to epiphyte richness in temperate deciduous forests, using the Söderåsen National Park in southern Sweden as a case study. My study focused on comparing the bird species richness and abundance across two site categories of forest which were previously identified as being high (Category A) or low (Category B) in epiphyte species richness. I inventoried bird species richness and abundance using point count surveys which were conducted in early spring, while focussing on those individuals that were exhibiting territorial behaviour. A total of 406 birds of 23 species were found, with 231 individuals displaying territorial behaviour. While no statistically significant differences in overall bird species richness or abundance were found between the site categories, sites with higher epiphyte richness showed higher numbers of insectivorous bird species and abundance exhibiting territorial behaviour. The red-listed Marsh Tit (Poecile palustris) was only found to showing territorial behaviour in the epiphyte rich site category (A). These results suggest that epiphyte rich forest may support a distinct bird community, possibly due to greater habitat complexity, although a direct causal relationship remains unconfirmed. This study highlights the ecological importance of maintaining a heterogeneous forest landscape and calls for future research, especially during periods when migratory bird species are present to clarify whether any link occurs between sites rich in epiphytes and sites rich in bird diversity.