Prairie dog review shows where they expand, lose and retake territory

This year, there are more prairie dogs where Boulder County wants them and fewer acres where they don't. The recent annual management review of the county's open space properties took stock of last year's efforts that see-saw between killing and nurturing, depending on where the animals live.

There are fewer acres with prairie dogs on agricultural open space, which are generally classified as No Prairie Dog acres or NPD. In 2020, prairie dogs lived on 2.5% of NPD acres, down from 4.1% in 2019. "We are getting there," said Boulder County Agricultural Resources supervisor Rob Alexander during the videoconferenced public presentation.

Quantifying the number of actual prairie dogs that were exterminated is complicated, so the county lists the number of burrows treated by carbon monoxide or carbon dioxide poisoning. Last year it was 37,217. "One of the things we would love to know is how many prairie dogs we are actually killing - there is no nice way of saying it. [Whether] we killed 28,000 or 24,000 prairie dogs, it's still a lot," Alexander said.

The challenge is that prairie dogs can use multiple burrows and the size of family groups, called coteries, can vary. Coteries generally consist of one or two males, several females and their young. It can range from one to 26 prairie dogs, according to the National Park Service.

Alexander said 1,265 animals were live-trapped on NPD properties and delivered as food for the Birds of Prey Rehabilitation Center and the Black Footed Ferret Recovery Facility.

The presentation included several maps that showed where colonies have been eliminated and where they snuck back. Alexander focused primarily on the AHI agricultural complex of about 1,700 acres that is roughly between 75th Street and 63rd Street, between Nelson Road to the north and Oxford Road to the south.

The county put 75% of its effort on those properties as part of a strategy to eliminate prairie dogs in one place before moving on to the next. Alexander said that has been the approach for the past four or five years.

Before that, the county did partial extermination of multiple colonies, but they repopulated, creating a deadly cycle. "Our strategy now is to clear properties entirely and stick with it and expose fewer prairie dogs to lethal control," Alexander said.

But that strategy isn't an exact science either as Alexander demonstrated with maps where prairie dogs have returned in force, including Lagerman Reservoir. The colony was cleared on the west side of the reservoir in 2018 and came back on the east side the next year when the county turned its attention to other priorities. "They are really adaptable, they are amazing, amazing animals. Incredibly tenacious, very tough," Alexander said.

On the agricultural properties, the county does the initial clearing, but it depends on farmers who lease the land to take over from there to prevent recolonization. "They will always return. But the key is to remove those animals as soon as they return; usually it's one or two or three. The tenants are there every day, it's much easier for them to do the control and maintain it that way. That's what we expect," Alexander said. Tenant farmers handled nearly 7,000 of the more than 37,000 burrows treated.

The prairie dog removal budget is expected to be about the same this year, but Alexander is aiming for an increase in 2022 to hire more seasonal employees. He estimates that the county will wrap up the initial clearing of NDAs in five or six years.

Lindsey Sterling Krank is a Boulder County resident who works on prairie dog conservation for The Humane Society of the United States. She commented during the meeting that she would like to see the county to be more creative in its management techniques.

Krank said the best way to reduce the lethal cycle is to put more effort into preventing prairie dogs from recolonizing sites where they aren't wanted. "They didn't get the memo that they can't live there. It completely looks like a great home to them. So can you grow a buffer zone, can you put up a barrier, can you grow a different crop? What are ways we can turn water on and off to encourage them to migrate into directions where we do and don't want them? Just different ideas that are non-lethal to prevent more of the same, which isn't working," she said.

Learning creative ways of coexisting with native species like prairie dogs is also something Krank wants to see more of. She said prairie dogs provide food and shelter for a lot of other animals and can have positive impacts on the land, "Prairie dogs are a complex species to live with, I understand that, but they are one we've got to learn to live with because they provide a lot of ecosystem services to our lands, too. They provide nitrogen, they aerate the soil."

The county's annual update also included an increase in open space acres where prairie dogs are living. There are 3,671 acres with prairie dogs, an increase of 727 acres from 2019. Colonies are found in areas designated as Habitat Conservation Areas, HCA, and on Multiple Objective Areas, MOA.

Senior county biologist Susan Spaulding said the increase was due to open space acquisitions and colony expansion. The number of prairie dogs per acre varies, so the county does not estimate the actual number of individual animals.

Plague abatement was done on the South County Grasslands off Highway 93, and on the Rabbit Mountain Open Space, north of Highway 66. The goal is to grow the colonies in those areas, partly to reintroduce Black Footed Ferrets. Spaulding indicated there is a long way to go on the grasslands. A breeding population of ferrets needs 1,500 acres of prairie dog colonies. There are currently only 175 acres of active prairie dog colonies. Rabbit mountain is nearing 1200 acres.