Winter takes toll on deer
Fewer fawns only partly due to predators
Northwest Montana's whitetail deer population is in a downturn not seen since the brutal winter of 1996, according to recent fawn recruitment surveys.
Every spring, Montana Fish, Wildlife and Parks wildlife biologists spend several weeks in specific areas, counting deer and classifying the ratio of year-old fawns to adults.
The long-term average for whitetails in Region One is 49 fawns for every 100 adults. Last year the ratio was down to 29 per 100. This spring's survey results - 24 per 100 - indicate that the population is in a declining trend with fewer young deer on the landscape, said John Vore, the state's Flathead area biologist.
The last time the ratio dropped so low was in the spring of 1997, when it was 23 per 100.
The surveys do not produce a deer population estimate, Vore said, noting that this year's total sample of 6,683 deer exceeded last year's count of 5,112.
"Just because we counted more deer doesn't mean there's more deer," Vore said. "The purpose is to get that ratio."
The low ratios of the last two years will have compounding impacts on the population over the next few years. But Vore said the population will eventually go back into a growth trend, just as it did in 1999, when it bounced back to 62 fawns per 100 adults.
The declining ratios of the last two years are due to a variety of reasons: last year's protracted winter, deeper low-elevation snow and subzero cold snaps this winter, an abundance of antlerless deer permits in recent years, and of course, the combined impacts of a variety of predators.
"They are definitely part of the mix," Vore said. "But they aren't the whole story as some people think."
Bears and coyotes prey on fawns, while recently surging populations of wolves and mountain lions have a year-round impact on whitetail deer, their main prey base in Northwest Montana.
But Vore stresses that winter conditions are a major deer population driver. To make his point, he notes that Eureka area hunting District 109, where there was considerably less snow than elsewhere in Region One, had one of the higher fawn-to-adult ratios, 38 per 100.
Meanwhile, the Flathead Valley bottom's District 170, had a ratio of 25 per 100.
"For all intents and purposes, it's really a predator-free zone," Vore said, adding that the Flathead Valley had unusually deep snow early in the winter, and it set up and persisted into March.
Vore said winter mortality can carry on for months after the snow is gone.
"Winter stress-related mortality [continues' even into May and into June," he said. "They are in real poor shape and they are still losing weight."
The sudden diet change from dried-out vegetation to green vegetation takes a toll on young deer that are already drained, he noted.
"They are going through all kinds of physiological changes that are very expensive, energetically," Vore said. "That's a real hit for their system."
Last year, more than 5,000 over-the-counter "B-tags' for antlerless deer were issued in Region One.
Largely because of last year's survey ratios, the Montana Fish, Wildlife and Parks Commission scaled B-tags back to no more than 25 in most of the region's 19 hunting districts. And the commission eliminated the four-day period at the end of the season when antlerless deer could be harvested. The antlerless harvest this year will be limited to the first two weeks of the season.
"Because of the low fawn survival, hunters are going to be finding fewer yearling and 2-year-old bucks out there," Vore said, adding that those age classes are typically the most harvested because they are usually the most abundant on the landscape.
Reporter Jim Mann may be reached at 758-4407 or by e-mail at jmann@dailyinterlake.com