Do birds affect the amount of insect damage to trees in the tropical forest canopy?
In other words, are birds indirectly helping out trees by eating herbivorous insects? I examined this question through experiments, observations and comparisons between different forest types. In one experiment, I used canopy cranes to access exclosures placed in the forest canopy. Exclosures are structures designed to keep birds away from certain branches in the canopy. Because birds could not forage on these branches, the insects were free to chew away with impunity. Other branches were designated as the control branches and were open to bird foraging. A construction crane in the middle of a forest allows researchers to access the canopy of the forest. moreThe Smithsonian Tropical Research Institute built the first canopy crane, pictured here, in Panama. This crane was used by Sunshine Van Bael for her research. A comparison of the damage to leaves and the numbers of insects on exclosure and control branches demonstrated that birds limited insect density. At one site, the damage by h
