The skills involved require a great deal of training and require the researcher to be very fit, and if the researcher sees something interesting a half-dozen trees away from the one he's climbed, a great deal of effort is involved in descending then climbing the new subject. This greatly limits the pace of research. A few years ago, University of Washington researches hit upon the idea of erecting a large construction crane in the middle of a patch of old-growth forest, using it to haul researchers to various points within the canopy. Originally it was planned for northwestern Washington, but local timber communities, which figure that more knowledge means less logging, opposed the project, so it ended up being built in southern Washington's Gifford Pinchot National Forest. While the main focus of the project is on the phsysiology of trees, the Forest Service has taken advantage of the crane to conduct systematic point counts of bird species utilizing the canopy.
Point counts are a standard technique used by ornithologists.
The general idea is that a route is mapped, and then the surveying biologist moves along the route at a fixed pace, stopping at pre-defined points for fixed amounts of time, recording every species identified by sight or ear. The surveys are repeated systematically until the research project ends. Point counts conducted from the Canopy Crane are slightly unusual in that the routes are vertical, as well as horizontal. Since not too many biologists can identify birds by ear as well as sight, this and other bird survey projects often make use of skilled amateur birders, such as myself. We began in the pre-dawn, as early morning is when birds are most active, particularly in warmer seasons.