Print PageChilean temperate rainforests are characterized by an evergreen multi-layered canopy, with emergent trees, and a complex understory with presence of bamboo tickets, logs, and dense regeneration of shade-tolerant trees. These forests are inhabited by around 40 bird species, often dependent on structural elements such as large trees for nesting, feeding or protection from predators. Despite these important bird-vegetation links, classifications of bird habitat are gross, often assigning birds to land cover categories (forest, grassland or shrubland), without concern for bird perceptions. Here, we: i) synthesize current knowledge of Chilean bird life history and habitat use, ii) provide definitions of habitat use, based on bird perception, and iii) propose improved guidelines for research and conservation of forest birds in changing, human-dominated landscapes. We review 12 years of data on structures used by birds for feeding, perching and nesting in temperate rain forests, based on 300 hours of surveys, including over 150 hours of records using canopy access techniques. The information was analyzed by cluster analysis, complemented with assessment of bird aspect ratios, which provide a morphometry-based estimate of bird flying capacity.
Results/Conclusions
We classified birds as: i) habitat generalist ii) large canopy trees specialist, iii) habitat generalist that commonly use large trees, iv) understory users, largely non-volant, and v) users of scrublands and other non-forest vegetation. The large Magellanic Woodpecker (Campephilus magellanicus) was predominantly associated with the presence of old Nothofagus trees, while understory users had marked preference for forest bamboo tickets. Most understory birds occurred where dense vegetation was present, regardless of the presence of trees. However, understory-dwelling Scelorchilus rubecula and Pteroptochos tarnii required habitats with tree cover. Understory birds showed low aspect ratios, and hence had limited dispersal ability. In managed rural and urban landscapes, occurrence of forest birds depends on the presence of remnant habitat fragments conserving large trees and dense understory cover, which are inter-connected by densely covered corridors. In forestry plantations, generalist and understory birds may occur associated with remaining understory vegetation. The conservation of forest birds in human-dominated landscapes is only possible when structural elements that are recognized by birds as habitat can be preserved. Further information on breeding biology and fine grain analysis of bird life history, dispersal and habitat connectivity in managed landscapes is needed. Analyses based on bird perceptions should replace investigator-laden classifications of land cover.
Acknowledgements: Conicyt PDA-24.
