Sep 3, 2026

Dogs and Wildlife in Boulder: Bears, Lions, Prairie Dogs

Three species shape how you walk a dog here, and one of them generates a fine the city will not quantify. What to do at an encounter, and why pet food in the car is a bear problem.

Luis ZamoraCo-founder of PetCompass; Dog Dad to Banzo and Tuck

Boulder, Colorado10 min readPet Care & ServicesThings to Do

In Boulder, chasing wildlife is not bad manners. It is a listed violation with a fine attached, and in one case the city says the law is broken by a dog chasing an animal it will never catch.

Three species shape how you walk a dog here: black bears, mountain lions and prairie dogs. The rules that follow from them are the reason Boulder's off-leash system is as conditional as it is.

The three species, and what each one changes

Each species comes with its own city guidance, and each one changes something about how you walk.

Species	What the city says	What it changes on a walk
Black bears	About 12,000 in Colorado and zero grizzlies, and all local bears are black bears even when the fur is brown or blond	Leash near streams, and consider a lead on all trails in active bear season
Mountain lions	Chances of seeing one are slight, an attack less likely still, and they are primarily nocturnal and secretive	Keep pets under control, bring them in at night, and do not feed pets outside
Prairie dogs	Chasing them is against the law, with a hefty fine the city does not quantify	Keep your dog away from prairie dog colonies

Chasing wildlife is one of the four things that ends your off-leash privilege

The city's Voice and Sight control standard requires you to be able to prevent four behaviours, and one of them is about animals. Verbatim from the programme page:

"Chasing, harassing, or disturbing wildlife or livestock; or"

And it appears again in the list of ticketable infractions, verbatim: "The dog chases, harasses or disturbs wildlife or livestock."

The standard is absolute. You must be able to prevent it "without regard to circumstances or distractions", which is the phrase that makes a deer at fifty yards a compliance question rather than a bit of fun.

Penalties run from a maximum of $100 for a first violation to not less than $300 for a third within 24 months, with possible suspension or permanent revocation of off-leash privileges. Our Voice and Sight Tag Program guide covers the ladder.

The city repeats the point on its trails page, verbatim from Dogs on OSMP: "it is illegal for you and your dog to chase or disturb wildlife or livestock."

Prairie dogs, and the fine the city will not quantify

This is the one that surprises visitors, because the target seems harmless and unreachable.

Verbatim from the Dogs on OSMP page:

"While it may seem like innocent fun to allow your dog to chase prairie dogs… "they'll never catch them anyway!"… it's against the law to do so and you could face a hefty fine! Keep your dog away from prairie dogs on prairie dog colonies!"

"It's against the law to do so." The city addresses the excuse directly and dismisses it.

We are not printing a figure, because the city says "hefty" and gives no amount. If you want the number, ask Animal Protection on 303-441-1874.

Why prairie dogs specifically? They are a colony species whose burrow systems support other wildlife, and Boulder manages them actively enough to run relocation and barrier programmes. A dog running a colony is disturbing an entire habitat rather than one animal.

Black bears, and the seasonal rule they generate

Boulder's bear season restriction is the single biggest seasonal change to dog access in the city, and our seasonal dog leash restrictions guide covers the dates and the named trails.

The wildlife context, verbatim from the city's bear and mountain lion page: "Wildlife scientists estimate that Colorado could hold about 12,000 black bears and zero grizzly bears."

And a detail worth knowing before you identify one at distance, verbatim: "All bears in the Boulder area are American black bears, even though some may not have black fur. It's not unusual for black bears to possess brown, cinnamon-colored or even blond fur!"

A brown bear in Boulder is a black bear. That matters, because bear-encounter advice differs by species and the advice below is for black bears.

The year-round instruction for dog walkers, verbatim: "Keep dogs on leash, especially near streams."

And the seasonal one, from the city's August 2026 release: "Consider putting your dog on a leash during active bear season on all trails for your dog's protection."

All trails, not just the restricted ones. That is the city recommending more than its own rule requires.

What to do if you meet a bear

Verbatim from the city's wildlife page:

"NEVER RUN. Running can make a bear chase you." "Keep your distance. Back slowly away facing the bear. Avoid direct eye contact." "Slowly and calmly leave the area. Talk aloud so the bear will become aware of you." "Be extra careful around a female with cubs. Never approach a cub." "Never throw food to distract a bear. This teaches a bear to approach people for food." "Fight back if attacked. Black bears have been driven away when people fight with rocks, sticks, binoculars, or even bare hands."

With a dog, all of that depends on the lead being short and in your hand. A dog at twenty feet makes the back-away impossible.

When to call 911, verbatim: "If the bear is threatening human safety, pets or destroying property, call 911."

And the reason the city cares so much

Verbatim from the bear news release: "bears that come into town for food and find it are more likely to stay. If they stay, bears are at risk of being killed for a number of reasons, including being hit by vehicles, being electrocuted by power poles, ingesting harmful chemicals and losing their natural fear of people, which may result in euthanasia by wildlife officers ."

The city's summary of the whole problem, verbatim from the wildlife page: "People create problem bears." / "Garbage kills bears." / "A fed bear is a dead bear."

One of the bear-proofing instructions is directly about your dog, verbatim: "Feed pets inside and store pet food indoors." And another, verbatim: "Keep a clean car. Never leave food, trash, pet food or coolers in your car. Bears will tear open doors and break windshields."

Pet food in the car is a bear attractant in Boulder. Take the kibble out.

Mountain lions, the quieter risk

Not seasonal, and the advice is different in kind.

The odds first, verbatim: "The chances of seeing a lion are slight, and even less likely is an attack by a mountain lion." And: "Although lions do live on Open Space, they are primarily nocturnal and secretive."

But the dog-specific advice is blunt, verbatim: "Keep pets under control. Roaming pets are easy prey and can attract lions. Bring pets in at night. If you leave your pet outside, keep it in a kennel with a secure top. Do not feed pets outside as this can attract raccoons and other animals that are eaten by lions."

Three separate instructions there. A loose pet is prey. A pet left outside overnight needs a secure top on its kennel. And feeding outside starts a food chain that ends with a lion in your garden.

What to do if you meet a lion

Verbatim:

"Do not approach lions. Most mountain lions will try to avoid a confrontation. Give the lion a way to escape." "Stay calm if you come upon a lion. Talk to it in a firm voice in an effort to demonstrate that you are human and not its regular prey." "Back away slowly. Running may stimulate a lion's instinct to chase and attack." "Face the lion and make an effort to appear as large as possible. Open your jacket or lift objects to appear like a more formidable opponent. Pick up your children." "If the lion behaves aggressively, throw rocks, sticks or whatever you can pick up, without turning your back to the lion or bending down." "If the lion would happen to attack, fight back. Lions have been driven away by prey that fights back. Remain standing and keep attempting to get back up if you are brought to the ground."

Note "Pick up your children" and the absence of "pick up your dog". A small dog is a decision you will have to make in the moment; a large one is not liftable. Either way, the lead is what keeps the dog beside you rather than running, which the city warns "may stimulate a lion's instinct to chase".

Why relocation is not the answer, verbatim: "When a mountain lion establishes its territory, it is often the only lion in that area. If a mountain lion leaves its territory, another mountain lion takes it over. Because of this, removing or relocating lions observed in the city does not reduce potential conflict."

The practical version for a dog walk

Leash near water. The city says it plainly, and streams are where bears and prey concentrate.

Leash on all trails in bear season, which is the city's own recommendation beyond the mandatory areas.

Do not let the dog work a prairie dog colony, even at distance, even on a lead if it is lunging. It is a legal issue, not just a wildlife one.

Keep the dog in at night, and secure any outdoor kennel with a top.

Take pet food out of the car and store it indoors.

And if your recall does not hold against a moving animal, do not use voice and sight at all. The city's own advice, verbatim from the Dogs on OSMP page: "Not sure what your dog will do when encountering wildlife on Open Space? Play it on the safe side and leash your pup until you or the wildlife has passed."

Our dog training for voice and sight control guide covers the city's own coaching on building that reliability, including its point about wind carrying your voice away from the dog. Our dogs on OSMP trails guide covers where each regime applies, and our Boulder dog parks guide covers the fenced alternative when the answer is no.

If something does go wrong, our emergency vets in Boulder guide has the two verified 24-hour hospitals, and wildlife incidents are referred by the county to Colorado Parks and Wildlife on 303-297-1192.

Two more of our guides matter here. If your dog chases wildlife and does not come back, our lost dog in Boulder guide has the two animal control numbers and the jurisdiction split between them. And on county open space, where rattlesnakes and cacti join the list, our dogs on Boulder County open space guide covers a separate set of rules with four properties closed to dogs entirely.

Frequently asked questions

Is it illegal for a dog to chase wildlife in Boulder? Yes. The city states that it is illegal for you and your dog to chase or disturb wildlife or livestock, and chasing, harassing or disturbing wildlife is one of the listed Voice and Sight infractions.

What happens if my dog chases prairie dogs? The city states that it is against the law and that you could face a hefty fine. It does not publish an amount, so ask Animal Protection on 303-441-1874.

Are there grizzly bears in Boulder? No. The city states that wildlife scientists estimate Colorado could hold about 12,000 black bears and zero grizzly bears, and that all bears in the Boulder area are American black bears even where their fur is brown, cinnamon or blond.

Should I leash my dog during bear season even on unrestricted trails? The city recommends it, advising walkers to consider putting a dog on a leash during active bear season on all trails for the dog's protection.

What should I do if I meet a black bear while walking my dog? Never run, keep your distance and back slowly away facing the bear, avoid direct eye contact, leave the area slowly while talking aloud, be extra careful around a female with cubs, never throw food, and fight back if attacked.

How likely is a mountain lion encounter? The city states that the chances of seeing a lion are slight and an attack is even less likely, and that lions are primarily nocturnal and secretive.

Sources

Wildlife guidance and seasonal rules change. Check the city's pages and the trailhead signage before you go.