Prairie Dogs Hack Baltimore Zoo

Fun story, with a lot of echoes of our own security problems:

It took just 10 minutes for a dozen prairie dogs to outwit the creators of the Maryland Zoo’s new $500,000 habitat.

Aircraft wire, poured concrete and slick plastic walls proved no match for the fast-footed rodents, the stars of a new exhibit that opens today.

As officials were promoting the return of the zoo’s 28 prairie dogs—their former digs had been out of sight in a closed section of the animal preserve for more than four years—some of the critters found ways to jump, climb and get over the walls of their prairie paradise, a centerpiece exhibit just inside the zoo’s main entrance.


But a few intrepid prairie dogs tried to find their way out, sending keepers scrambling to plug escape routes.

An hour later, just as zookeepers thought everything was under control, one rodent made it to the top of the wall. A dozen workers closed in. The prairie dog seemed to think better of it and jumped back into the enclosure.

“They find all the weak spots and exploit them,” said Karl Kranz, the zoo’s vice president for animal programs and chief operating officer.


Zoo staff members say the animals cannot burrow their way out because the former Kodiak bear environment is essentially a large concrete swimming bowl. The soil depth at Prairie Dog Town ranges from 6 feet to 8 feet.

“The dirt must be deeper than 36 inches in order for the prairie dogs to make their burrows under the frost line,” Kranz said. “We took soil samples from the old exhibit so the soils could be matched exactly to what they were used to having.”

After foiling the escape attempt, zoo workers adjusted wire fencing and installed more slippery plastic on the walls.

Posted on June 16, 2009 at 7:24 AM32 Comments


Tom M June 16, 2009 9:17 AM

They’re clearly too dangerous to be allowed on U.S. soil!

They must all be sent to Gitmo immediately!

The American people must be kept safe from these terrorist rodents!

[satire off]

RvnPhnx June 16, 2009 9:22 AM

Apparently these people have never had a hamster, nor read “I, Houdini” (Lynne Reid Banks; Random House; ISBN-13: 9780440419242).

Landon W. June 16, 2009 9:40 AM

An interesting post, but I was unaware that Prairie Dogs were so popular. Unfortunately, when I lived in West Texas they were considered pest and were typically relocated, because of the damage they caused to the agricultural industry.

Petréa Mitchell June 16, 2009 9:43 AM

Some years ago, I and a couple family members were at the Oregon Zoo and stopped to look at the meerkats in their temporary residence, which was a completely enclosed indoor space with a layer of sand on the floor for them to dig in. They were hard at work on a burrow, and everything seemed fine… until one of them emerged from it carrying a drain cover.

We alerted the nearest zookeeper. To this day, seeing meerkats gets the theme from “The Great Escape” running through my head.

bob June 16, 2009 9:45 AM

Beagles are escape artists as well. To reliably fence in a Beagle you need a footer 3 cinder blocks deep below grade level, a chain-link fence at least 6′ tall and a 90-degree inward pointing section of fence 6″ wide at the top. Ironically, one year a (presumably suicidal; or perhaps he had tularemia and was going to “take one for the team” to try and infect the dogs) rabbit broke -into- the pen of our best hunter. Well, I dont actually know for a fact that the entire rabbit broke in, but at least his spine and right rear foot did.

Bill June 16, 2009 9:47 AM

When I was a kid, my mum sectioned off some of our land to give our dogs “a good run”.

I said they’d have nothing better to do than try to escape into the surrounding countryside. I guessed after a day or so but she disagreed.

We were both wrong. They were out within the hour, but back by dinner time.

So, species listed by decreasing order of intelligence: Dogs, Prairie Dogs, Humans.

PackagedBlue June 16, 2009 10:20 AM

Containment is always problematic, and futile. Adjust expectations accordingly.

Humans are so into theater. Zoos, like us humans are really the master species, and keeper.

Jurassic Park style theater, just like current practices to make USA safer.

anonymous canuck June 16, 2009 10:24 AM

It’s not that humans are less intelligent. It’s just that the animals have the high ground – time and patience – they have nothing better to do than pick at things over time.

We humans tend to underestimate this far too often.

Also, since we feed and care for them we’ve already taken care of their basic Maslov needs and they can really focus and get in the zone.

I’ve seen dogs open cupboards, zippers closing kids knapsacks and lunches.

Mind you minutes and hours is both amusing and very impressive.

mcb June 16, 2009 10:26 AM

Hmmn, a well known reservoir of the plague with no respect for security policy, sounds more like the The Dirty Dozen than The Great Escape

On a sadder note, a few years back one of our local zoo’s meerkats managed to nip a visiting child. The parents refused rabies prophylaxis for their hominid so every meerkat in the exhibit was euthanized for rabies testing. Some times the fence is there to protect the critters from us…

Mark r June 16, 2009 11:45 AM

I’ve been doing battle with ants the past couple of weeks. They are taking advantage of a poorly-built addition to my house. They find a way in, I caulk it off, and two days later they’re coming in someplace else.

While each ant is pretty stupid, they never stop looking for a way in… And once one of them finds it, others immediately follow the scent trail, and one becomes a hundred really fast. They seem to have unlimited resources in terms of troop levels, and my victory looks far from certain.

It’s really humbling to be repeatedly bested by such tiny creatures.

Tangerine Blue June 16, 2009 11:55 AM

While each ant is pretty stupid

Discussing an ant is like dining on a bean.

It’s useless to think of ants as individuals; it’s an ant colony you’re fighting.

Davi Ottenheimer June 16, 2009 1:29 PM

Prairie dogs need more press like this, as well as study. They are funny and social creatures that are an essential element of a healthy prairie.

I am often saddened to see very simplistic risk models used to call for their destruction. It’s common for example for a developer to look across a prairie and say “there shouldn’t be prairie dogs here because their existence impedes our ability to treat this land as something other than what it is (a prairie)”.

Once a crew is done wrecking the habitat and destroying the prairie, they then fail to see the irony in calling prairie dogs invaders or complaining that they “destroy” their own native land.

While it is unfortunate that non-native and engineered species (like the artificially over-sized bovines) are typically unsuited and therefore unable to adapt to challenges of a prairie this is not the fault of prairie dogs. This is like saying getting wet when you jump in the ocean is the fault of the fish.

Slaughtering prairie dogs and treating them only as pests reduces our ability to learn from them and adapt better to the risks and environment in which they are an essential ingredient.

The slaughter of native species of prairie dogs over the past 100 years has lead to a 98% population decline, which is causing a cascade of new and potentially irreversible threats.

Prairie Dogs: Communication and Community in an Animal Society

“Prairie dog burrows act as aquifers that prevent water from eroding land while helping to cool it. Biology undergraduate Patricia Dennis is getting research experience working with Slobodchikoff. She is helping him take his inquiry to the next level by working to understand the meaning and ‘grammar’ behind prairie dog talk. ‘It’s hard to believe how smart these animals really are,’ she said. ‘We imagine that we still have a lot to learn.'”

magetoo June 16, 2009 2:10 PM


I know absolutely nothing about prairie dogs or the prairie, but your description of the situation is pretty much spot on for how I see the situation for wolves here in Sweden. They’ve been gone for hundreds of years but have recently made a comeback.

So what happens? The hunters call for their extermination — they can’t let their dogs loose in the forest for fear that they will be killed by wolves who see them as intruders. We can’t have the wild being that wild, you see. Again, it — and I’m stealing that great line — impedes our ability to treat the land as something other than what it is.

Ken Williams June 16, 2009 2:43 PM

At the Minnesota Zoo, they don’t worry about whether the prairie dogs escape. They escape routinely, in fact. But they make sure the environment inside the walls is inviting enough that the critters hang out enough on the inside that it’s interesting for people to watch.

Louis June 16, 2009 8:37 PM

Actually, what strikes me the most is that no one thought of putting one (or just a few) prairie dog in the habitat, to see how they would behave, try to escape, that sort of thing, and adjust from there.

Validation of the concept, dry run, work in progress, call it what you will…

Clive Robinson June 17, 2009 2:54 AM

@ Mark,

There are a couple of solutions to your ant problem 8)

The first being wipe out the queen and the nest, which is a bit drastic.

The second if you have the time is a lot more fun, but first you have to understand the ants…

As you have found caulking of their access point does not work, and will not work for a good reason.

If you regard an ant as a little automaton with a simple program which simplisticaly works as follows,

1, Follow food found scent trail.
2, If food is found return along trail with food leving more “food found” scent (exit success).
3, If food not found at end of “food found” trail randomly pick a forwards direction.
4, If “return scent found” go back to (3)
5, Start “forage mode” leaving “return scent”.
6, If food found then go back to (2).
7, If food not found after random time go back along return scent (still leaving more return scent) untill food found scent found, goto back to (3)

Although a bit more complex than I’ve shown it tells you why your caulking efforts fail. You have broken the “food found” sent trail so the ant goes into forage mode at your caulking and will eventually randomly find a way around it back to the food source.

The trick is to make the ant not follow the “food found” sent trail to your extension.

If you follow the ants back along the trail to the nest a little way and put a food source down then the ant will return to the nest with the food, after a little while the “food found” scent beyond fades away. By repeating the follow them back and leave a new food source you can lead them away from your extension and off in a totaly new direction.

If you don’t have the time etc, then find the nest and look for other exit points. Then take steps to kill the queen, which can be difficult as ants nests can go down forty feet underground.

The way I used to kill a nest is a bit drastic but it is effective and it also “salts the ground” so they don’t come back to the nest site again.

Put simply I “gas them” using Iron(III)/Ferric Chloride (common PCB etching crystals) and Sodium Hypochlorite (common house hold bleach).

It is the mixing of the two that liberates the gas chlorine and you realy realy don’t want to be breathing it (think First World War).

The way I do it is once you have located the nest and exit points make up a dilute solution of ferric chloride (PCD etching crystals and water) and pour down the exit points once a day for a few days this takes the ferric chloride deep into the nest. Then leave for a day or so then pour in the bleach and retire. This releses the chlorine gas deep in the nest and usuall kills the queen. It does however also “kill the soil” and things won’t grow there for quite a while.

RonK June 17, 2009 6:22 AM

@ Clive Robinson, Mark

I found your non-violent solution to ant infestation interesting. Have you actually invested that much effort into redirecting ant colony interests, and does it actually work in the long run?

I was a bit horrified at the drastic chemical (“final”) solution you proposed. For many (most?) types of ants, using a relatively innocuous IGR like methoprene (Precor) or nylar (pyriproxyfen, Archer) is quite effective in sterilizing the queen and causing colony collapse. Methoprene is actually so innocuous that the WHO recommends adding it to (open) drinking water wells in environments where mosquitoes (which would otherwise reproduce in the well) would carry dangerous diseases.

BF Skinner June 17, 2009 6:49 AM

You could spray cayenne pepper on to their trails. That seems to really irritate the little buggers.

Mark R June 17, 2009 7:41 AM

@Clive – Insightful as always. I was getting close to reversing the ant drone algorithm as you have defined it, but your version adds some detail in terms of the “failover modes”.

I think my situation may be hopeless. I never could find where they were actually getting into the house, but in the course of looking I realized that the addition is just too porous to be secured. Eventually we’re going to demolish it and rebuild (not just because of the ants).

They can come and go freely through the exterior of the addition, but that only gets them into an exterior wall. Then, the name of the game is “find a gap between the wall and the moulding”. I keep thinking I’ve caulked every possible entryway, but their continual brute force attacks keep proving me wrong.

As for going after the nest, I live in a city row house and only control a tiny patch of territory, and the ants respect no borders. I spent some time trying to find it, but the place is so overrun with what look like multiple populations of ants that I gave up on it. Most of the ants I see outside seem happy with leaves and twigs anyway. I’ve put out some baits now, which will hopefully at least cut down their numbers.

@RonK – caulk works well for blocking off one particular entry point; apart from physically closing the gap, it has a strong smell when first applied. The ants walk into the outer edge of the caulk line like a brick wall, since they no longer know where they’re supposed to go. Then begins what I call “the orgy of killing.” See, this is where the non-violent aspect breaks down. You will still have a large contingent of ants in your home, who now have no way out. They will spend the rest of their lives wandering aimlessly, trying to complete a mission that has been rendered (hopefully) impossible. In that respect, killing them seems relatively merciful.

Apologies to Bruce for hijacking his prairie dog thread to talk about ants. But I knew someone here would have good advice for me!

Clive Robinson June 17, 2009 1:13 PM

@ RonK,

“I found your non-violent solution to ant infestation interesting. Have you actually invested that much effort into redirecting ant colony interests, and does it actually work in the long run?”

Simple answer is yes,

Long answer, when I was younger insect behaviour fascinated me and I built my own formicarium and let them out on a table top zinc ointment or petrolium gel kept them confind to the top. When a little older the “micro mouse” events made me revisit what I had found out. Then I read Nobel prize-winning physicist Richard Feynman’s books and found out he also had been fascinated by the little varmints as well and had tried all sorts of litlle. Experiments as well.

The upshot is an ant will always find a way into your house irrespective of what you do. The trick is to make sure the little varmints leave empty handed, then they tend not to be a problem.

Whatever you do don’t kill them in your house or break their trail otherwise another ant is just going to follow it shortly, then another and another…

I agree the “final” solution is a bit drastic but the only stuff available back then was artificial/synthetic pyrethrins (called pyrethroids) which act as nerve agents (on humans fish ducks and other pets) and they where not very effective for various reasons (they oxzidze quite rapidly).

PackagedBlue June 17, 2009 11:50 PM

Ants do not like weed killer on dirt. Might be a safer measure for those into ant rights, and eco synergy.

Roger June 19, 2009 7:00 PM

I have finally gone through the photo essay as well as read the article. Looking at the detailed construction of the enclosure, it is obvious that it couldn’t restrain rodents. All the talk of “waist high glass” is meaningless: the photos clearly show that only four viewing points have those. Over most of the enclosure, a wire mesh fence is all the separates the animals from an easily climbable, naturalistic sculptured wall. And right in the first photo, beside the gate we see a gap under the fence that a small poodle could wriggle through. Most of the mesh isn’t even dug into the ground, plus the mesh is the ideal size to facilitate climbing by these animals. The one interesting aspect is that there seems to be a strand of electrified wire near the top of the fence, which at least one “dog” managed to climb past; it would be interesting to know how it did that. (Hypothesis 1: no-one knows what voltage / current characteristics to use to repel prairie dogs without injury, and they got it wrong. Hypothesis 2: it climbed across from the adjacent wooden gate, which has no electrified wire.)

I’d say the main security lesson from this is: sloppy building contractors undermine physical security design. And today’s building industry is rife with sloppy contractors (in fact, low standards are now the norm.) If construction standards are important to your physical security plan (and they usually are), then:
a) either require acceptance testing in the contract, or else only use a trustworthy contractor you’ve used repeatedly; and
b) expect to pay for quality. Even mediocre quality.

Leave a comment


Allowed HTML <a href="URL"> • <em> <cite> <i> • <strong> <b> • <sub> <sup> • <ul> <ol> <li> • <blockquote> <pre> Markdown Extra syntax via

Sidebar photo of Bruce Schneier by Joe MacInnis.