Availability of cavities for nesting birds in the Atlantic forest, Argentina

作者：Cockle Kristina^*; Martin Kathy; Wiebe Karen

来源：Ornitologia Neotropical, 2008, 19: 269-278.

• cavity nest
• cavity abundance
• cavity quality
• excavator
• nest site limitation
• parrot
• secondary cavity nester
• selective logging
• subtropical forest
• woodpecker

We test the hypothesis that selective logging reduces nest site availability and nest density for cavity-nesting birds in the Atlantic forest by determining 1) whether suitable cavities are as abundant in logged as in primary forest, and 2) the proportion of these cavities occupied by nesting birds. From September to December 2006 (breeding season), we counted all tree cavities in four 1-ha plots in each of primary and selectively logged forest in San Pedro Department, Misiones, Argentina. We measured all cavities below 15 m. We placed 26 nest boxes in 30 ha of logged forest at a nearby site, and measured 25 active cavity nests of 16 species of birds. Primary forest had significantly more cavities/ha than logged forest. In the plots, only one (5%) of the understory and midstory cavities (the deepest cavity, with a small entrance) and two (8%) of the canopy cavities were occupied by nesting birds. However, 13 of the 26 nest boxes were occupied. Natural cavities with characteristics similar to our nest boxes (>= 20 cm deep and <= 14 cm entrance diameter) accounted for nine (36%) of the 25 active natural nests; however, cavities conforming to the se characteristics were rare in plots in primary forest (1.3. +/- 1.0 cavities/ha) and rarer still in logged forest (0.5 +/- 0.6 cavities/ha). Thus, although low occupancy might suggest that cavities are not limiting, high quality cavities may-indeed be rare, especially in logged forest, and may Emit populations of some cavity-nesting birds in the Atlantic forest.

• 出版日期2008