The behavior and ecology of birds in tropical forest restoration sites

Forest restoration has become an important management tool that facilitates forest regeneration. However there has been little study thus far that examines how well restored plots, and particular planting designs, function over time in providing suitable habitat for tropical animals.;I examined the effects of restoration patch size on the foraging behavior of four resident tropical bird species. I also measure arthropod abundance and anti-predator vigilance behavior to assess whether variation in food availability or predation risk could explain patch size effects on foraging behavior. Prey attack rates were highest, and the effort required to find prey lowest, in larger patches for three of the four bird species. Arthropod density was approximately twice as great in larger patches compared to smaller patches. Evidence for patch size differences in predation risk was more limited but risk may be higher in smaller patches. The results indicate that food availability is the primary mechanism driving patch size effects on foraging behavior.;I compared the habitat quality of the active restoration sites with passive restoration sites, by measuring vegetation structure, arthropod biomass and the foraging behavior of three resident bird species. Although vegetation measures such as amount of understory cover and tree species richness and density differed between the two restoration strategies, arthropod biomass and foraging behavioral measures were similar. Results suggest that, while active and passive restoration strategies may lead to different vegetation structure, they may support similar biomass of foliage-dwelling arthropods and be similarly used by foraging insectivorous birds.;I also examined the effects of predator vocalizations (direct cues) on the vigilance behavior of birds foraging in different locations: small patches and the center and edges of large patches (indirect cues). Within feeder location, the time birds spent alert increased significantly after a predator compared to a non-predator (control) vocalization in all three locations. However, pairwise comparisons across feeder location showed that the change in time spent alert in response to the predator call was significantly greater in small patches and the edges of large patches compared to the center of large patches. Results show that birds perceive small patches and potentially, the edges of large patches as more risky habitats than the center of large patches. Birds responded more strongly to the direct cue of predation risk when foraging in these locations by increasing vigilance.;I then used an exclosure experiment to examine the top-down effects of birds and bats on arthropods and herbivory. Arthropod biomass was highest on tree branches where both birds and bats were excluded and lowest on branches without exclosures where both birds and bats were present. However, birds and bats had equal impacts on arthropod populations. The size of restoration patches had no significant effect on the impact of birds and bats on arthropod biomass, but did affect levels of leaf damage. These results suggest that both birds and bats play important roles as top-predators in restoration systems by reducing herbivorous arthropods and their damage to planted trees.