The iconic species is in decline. New data is helping game managers address the problem
On the road again: A group of mule deer bucks moves across Oregon’s Malheur National Wildlife Refuge. The state is watching. Photo: Barbara Wheeler/USFWS
By Kendra Chamberlain. April 16, 2025. As mule deer populations continue to decline across the West, the Oregon Department of Fish and Wildlife (ODFW) says it will use better data to manage its annual mule deer hunts.
Specifically, the department wants to update the state’s mule deer hunting units to track population changes.
“Mule deer are struggling across the western United States,” ODFW’s spokesperson Michelle Dennehy told Columbia Insight. “So this is very urgent, because we want to see the species continue to thrive, but they’re in troubled times. And that’s not just the case in Oregon—it’s the case all over the West.”
Hunters and conservationists alike have bemoaned the decline of the big-eared ungulate. But researchers are having a hard time understanding why exactly mule deer populations are suffering.
In Oregon, a 2022 count pegged the population at 162,600 animals, just over half of the 300,000 estimated in the 1980s.
Mule deer populations have always been variable year to year. But since the early 2000s, the state has seen a steady decline in the species, mirroring a larger trend throughout the West.
Habitat degradation
ODFW, like other state wildlife departments in the region, has spent the past decade conducting research to better understand why mule deer populations are struggling.
The department began deploying GPS radio collars on mule deer in 2014 to get a better sense of how herds move across the state. That research has led to stronger population models to monitor the species, incorporating data on herd composition, movements and survival rates.
In Oregon, at least, habitat degradation and loss appear to be the driving factors in mule deer declines. The species is struggling to find enough nutrition to support larger populations.
“Some of it’s related to changes in forest management. And we have invasive species like Medusa head rye that come up after fire—that’s reduced nutrition,” said Dennehy. “We’ve also seen that the growing season is shorter than it used to be, and that’s reduced their nutrition.”
Last year, the department adopted a new mule deer management plan to address population declines. The plan noted that it’s not just that the amount of habitat has decreased, but that the carrying capacity of the landscape (how many mule deer the remaining habitat can support) has decreased, too.
Oregon’s mule deer are likely suffering from “chronic nutritional stress in response to long term declines in carrying capacity,” the plan states.
Development also plays a role. Roads and fences can impact mule deer access to food and interfere with migration routes, the knowledge of which mule deer pass on from mother to offspring, generation after generation.
Renewable energy development is another rising threat to mule deer in eastern Oregon, as reported by Columbia Insight.
Updating obsolete boundaries
Oregon uses wildlife management units (WMUs) developed in the 1950s to control mule deer and other big game hunting. These units were designed to spread hunter distribution, but they don’t actually reflect how mule deer move across the state throughout the year.
ODFW has proposed updating unit boundaries to better reflect herd movements, rather than rely on the artificial boundaries enshrined in current WMUs.
Among other things, the change would allow the department to track population responses to actions aimed at helping the species recover.
“If we do something [such as] habitat improvement, we want to be able to measure the response accurately. And if we’re misaligned on our data, that makes it harder to detect the response,” said Dennehy.
Mule deer migration routes map: ODFW
The new hunting units will need to be approved by the Oregon Fish and Wildlife Commission later this year, and if approved won’t go into effect until the 2026 hunting season.
If approved, the change would present a major shift in mule deer hunting units in Oregon, said Dennehy. The units will be larger than the current WMUs and likely have different names.
“Changing it for hunters is a big deal because they’re accustomed to this hunt structure. There are hunters out there who’ve been putting in for years for a particular hunt and that’s part of the reason we’re getting out a year in advance,” she said. “We know how important this is to hunters.”
Not to mention mule deer.
In light of all the thoughtful responses about predation to this article (for which Columbia Insight thanks its readers), it’s worth noting what the Oregon Department of Fish and Wildlife’s 2024 Mule Deer Management Plan (linked above in the “Habitat Degradation” section) has to say on the subject (pp.133-34): “Oregon’s mule deer populations have experienced significant declines over the past several decades and predation from cougars (for adult mule deer) and coyotes (for newborn and juvenile mule deer) have been documented as the principal source of mortality. Because of this, predation is often implicated as the main driver of population declines, yet efforts in Oregon and other states have failed to show long-term increases in mule deer population growth resulting from predator removal efforts. Ultimately, predation interacts with a range of other factors (e.g., weather, habitat quality, disease) that will influence how much it is either additive or compensatory and affects population growth. All these interacting effects should be considered when attempting to manage predator populations to influence mule deer population performance.” Thank you for your continuing support of Columbia Insight. —Editor
Cut down the number of wolves and cougars, then we’ll see mule deer making a big impact on herds
Amen !!! Kinda funny that not a focus at all for odfw ??
At our ranch we use to see hundreds of deer in the valley, now we’re lucky to see a dozen. Hardly any cattle grazing anymore, so the habitat is better than its ever been. We have 13 does that stay by the house and only 1 fawn survived to spring. Preadators.
Kendra,
Respectfully, for you to not even mention predators as being part of the problem is not only alarming, its that very negligence of acknowledging predators that actually is the problem. I can give case after case example after example of how predators are playing the largest role in our mule deer decline.. We haven’t had a winter kill in southeast Oregon since 1992 and our deer numbers have dwindled to the point of nothing. I literally grew up on Hart Mountain and the Trout Creek Mountains hunting and know each range inside and out. Each place all during the ’80s you would see 40 to 50 bucks each morning glassing. Now you literally can’t find 40 bucks in a week. Steens, same thing.. Hart Mountain officials finally acknowledged their problem in studying the near extinction of the sheep population on the refuge and have started to act accordingly. But look what it took, it took the sheep heard to dwindle from 966 in 1991 down to 88 before they started conducting predator management, primarily cougars. 88! And then to put the icing on the cake they’re finally doing something about the cougars and then the whole Mountain burns down.. Nuked. Can’t win… And do you think that Oregon would reduce the tags significantly given the dire shape of the mountain… Nope. I naively assumed there would not be any deer hunts up there in 2025 given it just burned over 300,000 acres of prime habitat, scorching the vast majority of the deer habitat. With that, it was a only a matter of time before a catastrophic fire occured with removal the cattle in 1992 and resulting in a massive unhealthy thick rangeland. So mother nature kicked in and a catastrophic fire ensued. And I’m not even a cattle rancher! But managed correctly it’s a fantastic necessary tool to prevent catastrophic fires while fostering more mosaic fires and keeping the range healthy.
Finally, don’t take my word for it, you know, someone who’s passionately been out there for 45 years.. Just look at the bar graph on the mule deer studies in the 70s and 80s, and everytime the predator numbers go up the mule deer numbers go down and vice versa, reduce predators and deer numbers go up….
Manage the predator and you’ll see the deer come back!! Until then, it’s simply stark and sad..
C. Duncan
^ c Duncan is 100% correct
In Southern Oregon i gave observed the changes also. I do live on a very busy Urban wildlife trail that runs through my property.
The bear population keeps getting larger along with the cougars & coyote and the deer herds have dwindled to small groups of families. These deer have no chance unless we equal their predator field out a little. I have never understood the part about “We can shoot them but not feed them ” ?
Wolves, bet the mule deer decline mimics the wolf population rise. Bring back hound hunting for cougars and bears , while we still have any mule deer.
Respectfully, let’s face the fact about the real issue of the decline of mule deer in our state of Oregon:: PREDATION AND POACHING!!!! We live in the Paulina unit where we have hunted for over 50 years. Predator numbers must be managed. Cougars, wolves, coyotes and bears. We will NEVER see our numbers increase until this happens.
I agree. IQ doesn’t mean life intelligence. It take someone who’s been out in the real world to know what’s happening. When a kid in the 60’s we use to see 200-300 deer a day during hunting season. Now lucky to see 2 or 3. It’s absolutely crazy they didn’t report anything about predators and they’re increasing numbers. And now they actually money from our hunting permits and taxes to important MORE predators. Then when someone kills a wolf they have a larger reward than if someone killed another human so that shows you their priorities! Yes bring back dogs and bear baiting and coyote contests and the hunters will take care of the problems.
Just like the wolf, cougar, bear, walleye, and sea lions, all predators. Manage them, and the rest follows.
I’ve been bow hunting for over 40 years in Central Oregon. Same place same unit. I see more bears and Cougars and now wolf tracks than deer in a day. Especially bears since they don’t use dogs anymore like in the early years when I used to see lots of deer every day. Must be no food for the deer and elk?
I agree! I’ve hunted over 50 years and as soon as the stop to hunting with dogs started population dropped. It’s not only mule deer, elk, and sheep. Black tail numbers have dropped. I hunt every year so I know what I’m saying. We need people who hunt like me to have the correct input. A college degree and spending a small amount of time in the woods is not what Oregon hunters need to make this right. Just look at what a college degree governor did to our forests. We all see the burn of thousands acres and the same will happen to our wildlife. We must have a mix of folks working on this. When I worked for ODFW I could never get a full time position due to a family and best friend hiring. I’m a great worker and forever son of Oregon so getting a full time job shouldn’t have been a problem in the real world.
Columbia Insight welcomes comment and opinion on all stories posted on our website and social media platforms, including those that respectfully disagree or take issue with the facts or points of view presented in stories. We reserve the right to delete any comments that include profanity; are intended to induce rancor; are dishonest; or insult other members of our community. Comments on this story or posted as part of this thread have been removed because they do not align with these standards. —Editor
Predators
I’ve seen the same in CA, only worse. They banned hunting or even possessing any piece of a mountsin lion in the 90’s
I see more lions than bucks anymore. Now they want and are promoting wolves. The biologist need to get out in the woods frequently like some of us. Spend some days on end. Not just 9-5. Not manage animals through emotions and laboratories.