Point Counts On The Canopy Crane - Three Dimensional
Birding
Canopy Crane, Windriver Experimental Forest, Washington
Copyright © 1996, Don Baccus
(dhogaza@pacifier.com)
In the heart of the US Forest Service's Wind River Experimental
Forest, a construction crane towers three hundred feet above the landscape.
Its boom extends nearly as far, and we stand in a large, yellow gondola dangling
underneath. Why? I asked myself that question several hours earlier in
the pre-dawn darkness as Alan, in charge of safety, explained evacuation
proceedures in case a lightning storm came near and power to the crane
failed. "I'll hook on to your climbing harness and lower you to the
ground, my partner and I train for this several times a week", he said,
then asked me to sign a release informing me that there are unavoidable
risks associated with three-dimensional birding, and that the University
of Washington and the US Forest Service would not be liable if something
went wrong. The release also asked if I had any phobias that would
inhibit me from jumping from the gondola while a total stranger held the
other end of my rope. Figuring that common sense is no phobia, I lied and
said I'd jump anytime he asked.
Old-growth forests have played a predominant role in conservation politics
in the Pacific Northwest over the past several years. Well-publicized bird
species such as the marbled murrelet and the northern spotted owl have
been afforded protection under the Endangered Species Act. One of President
Bill Clinton's first acts in office was to appoint a committee of scientists
to craft a management plan for western coniferous forests in the Pacific
Northwest that would not only protect these already-listed species, but
would preserve sufficient habitat so that no other resident species would
have to be protected under the Act.
Many people are unaware of just how little we know about the ecology of these forests which once dominated those parts of the Pacific Northwest west of the Cascade Range. Dr. Eric Forsman, a researcher at the University of Washington, first calculated the size of breeding territories of the northern spotted owl in these forests in the mid-1970s. The first marbled murrelet nest in these forests was discovered just a few years ago. The relationship between root fungus and the northern spotted owl's major prey species, the northern flying squirrel, was worked out by University of Washington researchers less than two decades ago.
Yet, the US Forest Service continued to steadily clear-cut these forests, with the goal of converting them to managed single-species stands of even-aged trees, except for those small amounts protected in designated Wilderness or managed by the National Park Service. The Forest Service's official policy was that such conversion would not result in the loss of any of our biological heritage.
While today the Forest Service acknowledges the importance of old-growth
to the survival of a variety of bird, mammal and amphibian species, our
lack of knoweldge of the ecology of these forests hinders our ability to
tailor management plans to preserve them. The President's Forest Plan is
in part a crap-shoot, not because of sloppy work by scientists, but by
virtue of the fact that our knowledge base is too small to declare that
we really know how to manage our forests to meet aggressive timber targets
while protecting our biological heritage.
When we speak of the physiology of individual trees, of the insect, lichen, fungal and other communities that live in the tree's limbs and twigs in the canopy, and of bird and other species which depend on these communities, our knowledge is almost non-existent. Pioneers such as Oregon State's Bill Denison began climbing trees with mountaineering gear in the 1970s. While such work increases our knowledge, climbing trees is not an ideal technique for studying them. 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. Twelve stops are made, at three elevations (30, 60, and 90 meters) at each of the four compass points, fully extended along the boom.
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. This kind of field work is one of the few opportunities for amateur volunteers to make a contribution to science, and I always leap at the opportunity to do so, though this is the first time I was told that leaping might be part of the opportunity!
We began in the pre-dawn, as early morning is when birds are most active,
particularly in warmer seasons. This was summer, when most birds aren't
very vocal and many have begun their post-breeding dispersal. The crane
hummed, lifting us skyward along its supporting pylon, then out to the
end of the boom for our first count station 30 stories up. Listen, look,
identify, while trying to stay warm. I peered over the side, trying
to imagine launching myself over the rail. Over the course of the next couple
of hours, we gathered tiny tidbits of data to add to our overall knowledge
of this uniquely Northwest ecosystem. Performed weekly over at least two
years, these counts will add to our knowledge of how bird
species use these forests.
Of course, my noble urge to advance our knowledge of birds was only a small part of my motivation for participating that day. Who could resist the opportunity to sail throughout the upper canopy of a magnificent stand of trees, with only the distant hum of the crane's electric motors intruding on the quiet scene? Sunrise 30 stories above the forest floor is magnificent, and the gondola sways slightly in the wind as we conduct our count at each stop. Finally, in mid-morning, we're done, and the crane operator, sitting in his cab at the very top of the pylon, lowers us gently to the equipment shack at its base.
Just another day in the field!