Over the past 20 years conservation biologist John Koprowski at The University of Arizona has developed a wildlife capture method that keeps the animals calm so researchers can gather biological data.
A professor of wildlife and fisheries science in the School of Natural Resources of the College of Agriculture and Life Sciences (CALS), Koprowski's techniques have been so successful that he now has permission from the US Fish and Wildlife Service to handle species that are classified as rare and endangered.
"As you can imagine, they are quite reluctant to hand out a permit to just anyone," he says. "We had to prove my techniques and demonstrate that we could handle these guys safely." The end result is that Koprowski can obtain important ecological information with minimal detriment to the animals.
"We run them into a handling device that covers their eyes, and their heart rate drops," he says. The triangular-shaped canvas bag holds the squirrel in close, dark and tight quarters. "They get real mellow and we handle them quickly, less than five minutes." Koprowski's goal is to get the squirrels back into their territory as quickly as possible.
Koprowski is also director of the Mount Graham Red Squirrel Monitoring Project, where a great deal of his research takes place. "Because we're dealing with an endangered species - that's critically endangered with less than 300 left - we've got to take extra care that these things are protected," he says.
Most of the squirrels in the Southwest are diurnal - active during the day. In summer they are most active during the cooler parts of the day, thus in high summer the research team of seasonal technicians and graduate students sets up the traps first thing in the morning, soon after sunrise.
Monitoring takes place throughout the year. A quarterly trapping effort in March, June, September and December is designed to catch as many animals as possible to assess their survivorship and reproduction. The squirrels are also monitored at times when they are reproducing and the females are nursing their young.
There are five different squirrel species (or subspecies) of interest to UA biologists, ranging from introduced and nuisance species to those that are indigenous, rare or endangered. In the case of the Arizona gray squirrels (Sciurus arizonensis) and Chiricahua fox squirrels (S. nayaritensis chiricahuae) and the Mount Graham red squirrel (Tamiasciurus hudsonicus grahamensis), the populations have dwindled to the point that extreme care is taken in trapping and handling them.
Squirrels studied in other parts of the United States and Canada usually live between five and six years in the wild, or up to 20 years in captivity. But in Arizona, through the use of radio telemetry, researchers have found that a lifespan of more than two years is rare for endangered Mount Graham red squirrels. One year is spent growing up and another on the various adult things that squirrels do: finding a home, finding a mate and raising young.
"That tells you something is very different from areas where they are living five or six years," says Koprowski. "And we think part of that something is predation pressure - many of these animals die as raptor food."
Two of the raptor species that are feeding on the endangered Mount Graham red squirrel are actually limited in numbers themselves. Goshawks are a protected species and the Mexican spotted owl is a federally threatened species, which complicates some of the management schemes, according to Koprowski. "If you're trying to increase spotted owl populations, one of the things you'll want to do is promote conditions that increase food availability," he says. "Yet that food is an endangered species."
Much smaller than their eastern and northern relatives, the squirrels of Arizona live and die by the health of the "sky island" forests. The term was coined in 1967 for mountaintops of forest surrounded by desert and grasslands in the Southwest. When drought, fire or insects strike, the squirrels often react by having fewer offspring. Thirteen distinct mountain ranges in Arizona are categorized as isolated sky islands. Koprowski is studying and overseeing student research projects on squirrels, other mammals and reptiles in four of these sky islands.
"Much like the miner's canary, squirrels can tell us if the forest is changing and what directions some of those changes are going in," he says. "They are well-adapted to forest life and require mature, healthy forest to be able to survive."
Since 1989 UA researchers have been gathering population information about the Mount Graham red squirrel. In the past five years, aided with radio telemetry and geographical information systems (GIS), Koprowski and his award-winning research team of graduate students have been able to add considerable wealth to the data. What they learn on Mount Graham - a relatively simple system primarily under the stewardship of the US Forest Service with few private developments - can be transferred to other ecological settings.
An extended version of this story is available at http://ag.arizona.edu/pubs/general/resrpt2006/article6_2006.pdf.
Contact John L. Koprowski, professor of wildlife conservation and management in the UA School of Natural Resources, at 520-624-6439. Koprowski's Web page can be found at http://cals.arizona.edu/~squirrel. An online tutorial about the Mount Graham red squirrel can be found at http://cals.arizona.edu/research/redsquirrel