Justin Primus has been scanning the ground for the telltale shade of soft green that, when present, can help determine whether deer live or die.

Mostly Primus has been seeing brown.

And more recently, as temperatures have dipped, the white of new snow.

Neither hue bodes well for Northeastern Oregon’s deer herds, and to a lesser extent elk, as they brace for winter.

It’s a season of deprivation for wildlife.

Some winters the temperature rarely goes above freezing for weeks and occasionally plunges below zero.

Snow covers the grasses and shrubs that deer, elk and other herbivores depend on for food, forcing the animals to expend energy digging through the drifts.

With forage scarce during winter, deer and elk depend on the fat reserves they accumulate during the summer and fall, said Primus, assistant district wildlife biologist at the Oregon Department of Fish and Wildlife’s Baker City office.

The best scenario for the animals, Primus said, is when autumn is both mild and occasionally damp, a combination that can spur grass, desiccated by summer heat, to send out lush new sprouts before the snow returns.

Biologists call it the fall greenup, and it can literally be a lifesaver for beleaguered wildlife.

Deer, in particular, lacking the body mass of elk, are especially vulnerable, biologists say.

During the winter of 2016-17, for instance, when snow accumulated to depths of 2 feet or more even in the valleys and temperatures plummeted to 20 below zero, hundreds of deer died across Northeastern Oregon.

The Oregon Fish and Wildlife Commission responded by cutting in half the number of hunting tags for the 2017 deer season. Tag numbers haven’t returned to levels prior to that winter, the most severe in the region since 1992-93.

“I hope we don’t get a super-hard winter,” Primus said.

A tale of two years

The problem with this year’s greenup, said Primus and several other ODFW biologists around the region, is that it’s largely absent.

“We didn’t get any fall greenup in Baker County this year,” Primus said on Nov. 14.

Phillip Perrine, a biologist at ODFW’s La Grande office, had a nearly identical assessment for Union County’s deer range.

“Not good,” Perrine said on Nov. 14. “There’s not a lot of extra forage.”

The situation is similar in Morrow County.

“We’re not seeing a whole lot of greenup,” Steve Terry, a biologist at ODFW’s Heppner office, said on Nov. 18.

Lee Foster, a biologist at ODFW’s office in Hines, offered a slightly more optimistic outlook for parts of Harney County.

“We’ve had quite a bit of moisture this fall, and we’re seeing a little bit (of new grass),” Foster said.

But a lot less than in 2023.

That’s a regionwide trend, the biologists said.

A year ago, they offered a selection of superlatives to describe the fall greenup, among them “fantastic” and “phenomenal.”

The latter summer and fall of 2023 was much wetter than the same interval this year.

At the Baker City Airport, for instance, there was more than twice as much rain from Aug. 1 through Oct. 31 of 2023 as for the equivalent period this year.

At the Eastern Oregon Regional Airport in Pendleton, that three-month period was twice as damp last year as this year.

But the difference wasn’t limited to the amount of moisture, Perrine said.

When the rain came was about as important as how much fell, he said.

This year much of the rain arrived after the equinox, with the second half of November being the dampest period. But by then the soil temperature had dropped, which stymies grass growth even when moisture is abundant, Perrine said.

“It’s hard to get a fall greenup when the soil temperatures are so low,” he said.

Primus agreed, comparing the situation on deer habitat to what can happen to a backyard lawn after the first few hard frosts.

“No matter how much you water it, it’s not going to respond,” he said. “The rain was a little too late.”

Perrine said he’s seen a modest amount of new grass in places such as open slopes at the edge of rock outcrops, where the stone, which can hold the sun’s heat, likely has kept the soil temperatures a bit warmer than in other areas.

The biologists agree that 2023 was not only a bountiful year for fall greenup but also an unusual one.

It had to do with a hurricane.

The remnants of one, anyway.

Although Hurricane Hilary was no longer a hurricane, it was still quite soggy when it moved through Eastern Oregon on Aug. 21, 2023.

The storm was particularly potent in Baker County, dropping almost an inch and a half of rain at the Baker City Airport, a daily record.

That deluge, followed by occasional showers during September, moistened the ground while the soil was still warm enough to allow grass to flourish.

The result was a landscape “literally green everywhere,” Brian Ratliff, district wildlife biologist at ODFW’s Baker City office, said in the fall of 2023.

Fire effects

Biologists say a widespread greenup this fall would have been especially welcome in the wake of the record-setting wildfires that burned tens of thousands of acres of deer winter range across Eastern Oregon this summer.

With the resulting loss of forage, a greenup “would have been nice to have,” Primus said.

Besides helping animals pack on fat reserves before winter, a flush of grass would have allowed deer to spread out rather than congregating in places where forage is available. When deer gather in large numbers they’re more susceptible to disease, Primus said.

Although the scarcity of new grass poses a potential problem for deer and elk if the winter is long and harsh, Perrine points out that by November the animals have started to transition their diet from grass to shrubs.

Unlike grass, shrubs such as bitterbrush and sagebrush don’t need much moisture to remain palatable to wildlife, Perrine said.

Elk vs. deer

The biologists all said that the scanty fall greenup poses a bigger threat to deer, both mule and white-tailed, than it does to their larger cousins, Rocky Mountain elk.

Foster said elk are more adept at moving to new habitat in search of more abundant forage.

Fires in northern Harney and southern Grant County this summer, for instance, burned significant swaths of elk winter range, Foster said.

But he expects the elk will migrate to areas with better forage.

Deer, by contrast, tend to be creatures of habit, Terry said, returning to the same places, including winter range, regardless of whether there’s sufficient food.

With the combination of scorched areas and the lack of fall greenup, Terry said he’s “a little more concerned about the deer than the elk.”

In addition to being more adaptable to changing habitat, elk, with their bigger bodies, are less susceptible to the deprivations of winter, Perrine said.

Benefits for bucks?

Although animals will take advantage of green forage at any point in the fall, a later greenup can give buck deer in particular a boost, Ratliff said.

Bucks expend a lot of energy pursuing does during the rut — the breeding season that typically takes up much of November.

Bucks can be vulnerable to hard winters if they can’t replenish some of their fat reserves before temperatures plunge and snow covers some of their feed, Ratliff said.

Fawns are also particularly vulnerable to harsh winters, along with older animals.

Terry said the severity of winter is not the only factor affecting deer and elk survival.

The timing of the coldest temperatures and deepest snow matters too.

If the polar periods happen early in the winter, when animals haven’t shed most of their fat reserves, they’re likely to fare better than if the worst of the winter arrives in February, Terry said.

More private land damage possible

Biologists said the paltry fall greenup could affect farmers and ranchers across the region by forcing deer and elk to move from their usual winter range onto lower-elevation private land, including alfalfa fields and hay pastures where forage is more abundant.

“I hope we don’t get a super hard winter.”

— Justin Primus, wildlife biologist, Oregon Department of Fish and Wildlife