Tuesday, 24 Jul 2001
MINERAL, Calif.
Why do certain animals occur in some places and not in others? This question, one of the oldest in science and natural history, still has bearing on wildlife research today. Every species is adapted for certain habitats or environments, and we would expect to find that species there and not in other places. Likewise, when habitats disappear or are destroyed, the species living there may disappear as well. Determining the relationship between a species and its habitat is a fundamental step in conserving both.
In our ongoing study of the threatened Sierra Nevada red fox, one of our primary goals is to learn where foxes occur and where they don't. This would suggest that one habitat is "good" for foxes and that the other is "bad." In reality, the situation is a bit more complex -- a perfectly good habitat just might not have any foxes in it right now -- but we have to start somewhere.
An aerial photo of Lassen Volcanic National Park showing various habitats.
Photo: John Perrine.
º? {?ch sites, Lassen Volcanic National Park and the surrounding Lassen National Forest, lie at the southernmost tip of the Cascades Mountains in Northern California. Together, the park and the forest contain more than a thousand square miles of wildlife habitat: barren rocky slopes, dense conifer forests, lush mountain meadows, bubbling streams, and fields of scrubby brush.
To find our foxes, we are using TrailMaster automatic camera stations -- perhaps one of the most promising and downright-fun new wildlife research tools to come along in decades. The stations consist of a motion detector wired to a simple point-and-shoot camera. The motion detector works just like the sensor on a back-porch light: When something comes walking along, it activates the motion sensor. In our case, instead of turning on a light, the sensor triggers the camera to take a photo. All we have to do is nail the sensor and camera to a tree and then come back in a week to see what critters happened to wander by.
To increase our chances of finding foxes, we put out some bait we hope will draw them to within range of the cameras. It's like a bizarre combination of security technology and fishing. Our current bait is rancid chicken legs, sprinkled with a little commercial trapper's scent-lure and a splash of red fox urine (you can order it by the bottle if you've got the right catalogs). The overall effect is somewhat overpowering. We don't know if the foxes find the smell delicious or appalling, but one way or another, it brings them in from miles around.
At any given time we'll have about 10 camera stations scattered throughout the park and the forest, in a variety of different habitats. Some of these stations will detect Sierra Nevada red foxes and others will not. Gradually a pattern emerges, indicating which habitats are likely to contain red foxes and which are not. It may also tell us how many individual foxes are in a given place at the same time, and whether they seem to be found in the same habitats as other species such as bears, coyotes, and bobcats.
It takes a team of two people at least a full day to check and rebait all the stations. Generally, one person changes the film and the batteries in the camera while another person sets out the bait. This keeps the bait smell from getting on the equipment, which seems to help stop the bears from eating our cameras. Checking cameras really illustrates the glamour inherent to wildlife biology: There's nothing like wiring some stinky, greasy, maggot-ridden chicken to a tree and then sprinkling it with fox pee -- especially right before lunch.
The real fun is getting the pictures developed and seeing just what animals came by our station in the last week. Was it a fox? A bear? A bobcat? Unfortunately, we have to wait until the end of the week before we get our pictures back.
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