Boulder County presents annual prairie dog report

On Dec. 14, Boulder County Parks & Open Space held its annual meeting to discuss this year's prairie dog removal activities and the population updates on burrowing owls and black-footed ferrets.

According to the presentation, removal occurred on 41 "no prairie dog areas" (NPD) properties on park or open space property, and tenants were treated on 19 properties.

As of this year, 6,099 burrows have been treated with gas cartridges, which produce smoke and carbon monoxide once ignited. Gas cartridges can be flammable and should only be used in non-grassy open fields. Carbon monoxide (CO) is a popular fumigant in prairie dog removal, as it is considered a humane method of putting them to sleep, and it does not cause secondary toxicity. For instance, if a hawk ate a prairie dog that died of carbon monoxide, the hawk wouldn't get sick or die from consuming it.

The other 23,579 burrows were treated with compressed carbon monoxide, which is piped down into burrows with hoses. Compressed CO is often safer to use than gas cartridges, as it is easier to target the burrowing system and there is no likelihood of causing a fire. In total, 29,678 burrows were treated and removal occurred on 318 acres.

There are a total of 17,198 "no prairie dog acres," but 4.4% of the land is currently occupied by prairie dog colonies. This year, 1,499 animals in total were trapped. 601 of them were taken to a black-footed ferret recovery facility and the other 898 animals were taken to a raptor rehabilitation.

Other non-lethal methods were used for prairie dog removal this year. Barrier fences were installed in a total of 6,475 feet on agricultural property and another 650 feet were installed due to "neighbor issues."

Boulder County has seen a decrease in prairie dog colonization this year in comparison to 2020. The Habitat Conservation Areas (HCA), also known as areas suitable for prairie dog habitat, totaled 1,150 acres, decreased by 26.28%. The Multiple Objective Areas (MOA), areas that can support prairie dogs with other activities, such as trails and grazing, totaled 1,670 acres, decreased by 20.89%.

Burrowing Owl Management has seen a decline in burrowing owl nesting since 2019, with less than 10 recorded sightings in 2021. The management team was operated by 29 volunteers and completed 685 hours surveying and monitoring the owls. From their collected data, the management team is proposing stronger maintenance of prairie dog populations to provide burrows for owls to nest in. The number of habitat acreage required to improve burrowing owl populations is still undecided.

Recent success has been found in black-footed ferret populations. Delta Dust, a waterproof dust used for eliminating pests, was used in prairie dog colonies within the South County Grasslands and on Rabbit Mountain since 2016. The prairie dogs living in those areas have been treated by the Sylvatic Plague Vaccine this year. The sylvatic plague is a bacterial disease transmitted by fleas. Prairie dogs are susceptible to this, which results in the decline of black-footed ferret populations, the rarest mammal in North America, as the ferrets depend on them for food and shelter.

So far, 52 acres of the South Grasslands and 1,096 acres of Rabbit Mountain have been treated with the vaccine, which is covered in peanut butter as a tasty bait. The current annual costs for the sylvatic plague vaccine, the delta dust, and the labor required is $21,286. The costs and materials are expected to increase as colonies grow.

The management team at the Carolyn Holmberg Preserve at Rock Creek Farm is considering removing the lethal control moratorium. The team reported, "Exterminations will not occur during the pup-rearing time period of March 1 to May 31 annually. This timeframe was selected to capture the peak rearing season to limit the potential of young being left unattended in the burrows. The exception will be in cases where dispersing individuals attempt to colonize an NPD without prairie dogs. If these areas are free of prairie dogs as of March 1 of each year, direct lethal control may be used to prevent recolonization during this time period."

The report also stated, "Removal of the moratorium would result in fewer prairie dog deaths due to better overall control and reduce on-going impacts to agricultural properties and tenants."

"Given current staffing and resources, staff have not been able to successfully clear NPD areas with the moratorium. Staff request will be to lift the moratorium," the team concluded.

As of now, staff proposed changes to Section 8.3.3 of the Prairie Dog Habitat Element of the Grassland and Shrubland Management Policy regarding the seasonal moratorium on lethal control. This item is scheduled to be presented to the Parks & Open Space Advisory Committee (POSAC) on Thursday, Jan. 27, followed by a presentation to the Board of County Commissioners (BOCC) for approval on Feb. 10.