O ne year ago Baker County’s deer herds were in trouble.
Snow lay deep, in places more than two feet, even at lower elevations where the animals gather during winter.
Temperatures had stayed below freezing for more than three weeks in a row, and on more than 10 days plummeted below zero across most of the county.
To describe the current winter as different is accurate, but it doesn’t completely capture the discrepancy, Brian Ratliff believes.
Ratliff is the district wildlife biologist at the Oregon Department of Fish and Wildlife’s Baker City office.
The term he uses to compare this winter with last is “completely opposite.”
The result, Ratliff said, is that deer, instead of being on the brink of starvation, generally are thriving.
“This mild winter that we’re having — and I will call it mild — is just great,” he said Tuesday afternoon. “It’s been phenomenal for deer.”
For a couple points of comparison, in December 2016 the average low temperature at the Baker City Airport was 4.9 degrees, and the temperature dipped below zero on 7 days.
This December the average low was 14.7, and there were 2 sub-zero days.
But the airport temperatures don’t even tell the complete story as it relates to deer herds, Ratliff said.
Another significant difference between the past two Decembers is that the 2017 version was dominated by a temperature inversion, in which the airport on many days was colder than the surrounding hills and ridges where many of the county’s deer winter.
“A lot of animals are above the inversion,” Ratliff said — which is to say, they’ve enjoyed warmer weather than the airport’s temperatures depict.
In any case, Ratliff said typical December temperatures in the 20s pose little or no threat to the well-being of deer or elk.
“Below freezing for us is cold, but below freezing for elk or deer is not,” he said.
The animals — and in particular elk, which are bigger and better able to endure cold weather — don’t burn appreciably more energy to stay warm at 20 degrees than they do at, say, 40, Ratliff said.
He said research has shown that a healthy mule deer at rest doesn’t start burning its fat reserves, just to maintain its body heat, until the air temperature dips to about 2 below zero.
The equation that biologists created to predict how the weather affects a deer’s caloric needs is rather more complex — it takes into effect wind speed and whether skies are clear or cloudy, among other factors.
But Ratliff said the gist of the research is that weather that would prompt people to don an extra layer or two has little effect, if any, on deer and elk.
But the other notable difference between this winter and last — the amount of snow — does have a major effect on the survival rates for deer, he said.
With much of the county’s deer winter range snow-free or nearly so, the animals have easy access to dry grass and other forage, Ratliff said.
Moreover, the animals don’t have to expand vital energy plunging through belly-high snowdrifts while foraging for food or escaping predators, he said.
Although chilly temperatures don’t necessarily deplete a deer’s fat reserves, the animals do burn considerably more calories when they have to plod through deep snow. In that respect deer are similar to humans.
The scarcity of snow also gives deer a leg up, so to speak, over coyotes in particular, which are much more likely to catch and kill a deer when the snow is deep.
See more in the Jan. 3, 2018, issue of the Baker City Herald.