Western gray squirrel: Going nutty with no lovin' in the den
Seattle Times science reporter
"It comes down to six hours... probably," said John Koprowski, a University of biologist who has studied the western gray in Oregon. For males, "it's a long year."
And to make matters worse, eligible bachelorettes can be pretty hard to find when your population is in a tailspin.
Obviously, we aren't talking here about the eastern gray squirrel, the creature mugging your bird feeder day after day. The eastern gray is an import, brought to Seattle from Minneapolis in the 1920s by the director of the Woodland Park Zoo. It has since spread like Scotch broom across King County and is now bent on total world domination.
The western gray is a Washington native, first documented by Lewis and Clark at the Dalles, Ore. It lacks the brown highlights of the eastern gray and lives a more reclusive lifestyle made difficult by roads, housing developments, clear-cuts, irregular food and occasional bouts of deadly mange (a microscopic mite), not to mention the inconsistent sex.
It is now listed as threatened by the state Department of Fish and Wildlife. The last big population in the Puget Sound area was near Fort Lewis, where researchers in the early '90s counted 81 individuals. A more industrious survey in 1998 and 1999 found only six.
"When you're talking about so few animals, you've got to believe that population is no longer viable," said Ted Thomas of the U.S. Department of Fish and Wildlife.
Which brings us to a hilly patch of oak and pine in Klickitat County. On this day, state Fish and Wildlife biologists Matt Vander Haegen and Liana Aker are studying about a dozen western grays in one of Washington's last and certainly the largest refuge left for the western gray.
Klickitat County has the mix of oaks and ponderosa pine preferred by the western gray squirrel, but it still may not be ideal, said Mary Linders, a Fish and Wildlife conservation biologist who studied the squirrel for her University of Washington master's thesis. Western-gray home ranges here tend to be up to 10 times bigger than in Oregon or California, she said, suggesting it takes a lot of land to support a single squirrel.
That means a lot of extra work for the male western gray as he searches for a potential partner in heat. His quest may start in November, when his testes enlarge. They stay that way until July, all for a female in estrus just one day.
"The breeding season can run eight months," said Linders, "so the males run themselves ragged during the course of that time looking for females in estrus. It gets pretty crazy out there."
Washington's western gray has only one species of oak to live on, the Oregon white oak, which it supplements with seeds from the Ponderosa pine. Good crops come only every four or five years, so for much of the time dinner is larvae, bugs and fungus.
The squirrels' specific mix of trees is easily upset by forest practices, said Vander Haegen. Decades of fire suppression let ponderosa pine stands grow dense but small, leaving them more vulnerable to disease, drought and infestations of insects like the pine-bark beetle, a recent scourge. Clear-cuts can remove pine and replace it with Douglas fir, which the squirrels find less attractive.
The state Department of Fish and Wildlife, which listed the squirrel as threatened in 1993, is now working on a plan to help the squirrels recover, like leaving larger oak and pine trees and reintroducing the squirrels to certain areas. Vander Haegen and Aker are working on a project in which they twice a year lay out a gridwork of 144 traps in the Klickitat Wildlife Area. The area can have as many as 300 deer per square mile, but there are not nearly as many squirrels. One recent morning, the first three dozen traps checked by the biologists came up empty.
Finally, Aker radioed Vander Haegen: "I've got a gray in G-11."
"Hiya!" she said, peering into the cage. "You're looking kind of mangy aren't you?"
It's a bad year for acorns, which seems to be tied to an outbreak of mange, a microscopic mite that causes hair to fall out. When mange swept through the herd three years ago, many squirrels lost their hair, lost weight, grew disoriented, developed lesions, contracted infections and died.
The squirrel squealed like a dog toy under attack.
It was M-2252. In December, he had a good layer of fat and a beautiful, silver-gray coat. Now he was losing hair from his head, shoulders and forearms.
Vander Haegen has spoken with a veterinarian about treating the squirrels for mange but was told they would need repeated treatments, which would be impractical. It would also throw off the researchers' data.
Desperate for a meal, M-2252 may have willingly entered G-11 for the bait — walnuts — which he had eaten. A few hours later, he would reappear a quarter-mile away in I-7. He ate the walnuts there, too.
At G-6, in a dense stand of pine, the researchers found a healthier squirrel, its tail so bushy it filled the cage. It was F-2357, a female they had seen the day before.
Then, at J-4, they found F-2265, a female first trapped and tagged as a juvenile on Oct. 5, 2000.
Vander Haegen broke out his toolbox, which he had been carrying all day like a factory worker with a lunch pail. Out of it streamed a small field laboratory with Neosporin, radio transmitters and Top Crest coffee filters that fit neatly into the top half of a Cascade Clear water bottle, which acts as an ether mask. Aker dripped half a teaspoon of isoflurane, an anaesthetic, onto a cotton ball and placed it on the squirrel's cage.
Vander Haegen wrapped the cage in a plastic sheet. Five minutes later, he said, "down for the count," and pulled out a limp, slow-breathing squirrel. It had a splendid, finely textured coat of silver and black, gray and white. It slept like a cat in the sun.
Aker attached a new radio collar and the two checked her teats, which were dark and starting to enlarge and weighed her. At last, a good sign.
"She's definitely going to breed," said Vander Haegen. "She's in good breeding shape."
Natural Wonders appears every other Monday. Eric Sorensen can be reached at 206-464-8253 and email@example.com.