Burrowing Owls

Updated May 5, 2021

Why are burrowing owls relevant to the Redtail Ridge development?

Brue Baukol Capital Partners (BBCP ) purchased the former Conoco Phillips Site in Louisville in December of 2020. The approximately 400 acre site contains 142 acres of active prairie dog colonies[i] that are potential habitat for burrowing owls, a threatened species in CO. Burrowing owls are rare in Boulder County but have been found about a mile from the site at Carolyn Holmberg Preserve. If burrowing owls are found at the site, there are many ways to ensure their preservation.

What are burrowing owls?

Burrowing owls are small owls with long legs that are active during the day. They are uncommon summer residents in Boulder County, only coming north from Mexico for the breeding season. They lay eggs in abandoned prairie dog burrows early summer. They line their nests with dung to attract beetles for prey. The owls have declined significantly in Boulder County and in CO due to loss of nesting habitat.[ii]

Are burrowing owls protected by law?

Yes. Burrowing owls are listed as “State Threatened Species”[iii] in Colorado meaning that they are protected by the State Endangered Species Act [iv].  Burrowing owls are also protected by the Migratory Bird Treaty Act (MTBA). According to MTBA, killing or possessing burrowing owls or destruction of their eggs or nest is prohibited by law[v]. 

They are not listed as endangered under the federal Endangered Species Act (ESA), but could be listed in the future[vi]. 

How does the State Endangered Species Act protect burrowing owls?

It is unlawful to “take” species such as the burrowing owl that are listed by CPW according State Law[vii]. Any person knowingly “taking” burrowing owls can face criminal penalties. However, “take” permits can be obtained by CPW. The State Endangered Species Act is also proactive in species protection. It gives CPW funding and direction to protect endangered species through various programs.

What other policies protect burrowing owls?

Burrowing owls are listed as a Tier One Species of Greatest Conservation Need in the Colorado State Wildlife Action Plan[viii]. Burrowing Owls are listed as a Boulder County Species of Special Concern[ix].  The City of Louisville Comprehensive Plan[x] directs the city to “encourage ecological diversity through its… development and landscape regulations” and would therefore strive for protection of endangered species.

Boulder County staff, in a letter dated June  5, 2020, to the City of Louisville Planning  Manager, weighed in on the burrowing owl survey recommendation included in the BA. The County requests that the developer be required through development approval to take the measures necessary to protect burrowing owls and other raptors.

Is BBCP aware that burrowing owls could reside on the site?

Yes, a Biological Assessment (BA)[xi] was completed on behalf of BBCP by CTL Thompson, Inc. in February of 2019.

A major purpose of a BA is to evaluate for the presence of endangered or threatened species critical habitat.

The BA notes that the site contains suitable burrowing owl habitat. According to the BA, “burrowing owls are a threatened species, and are protected under federal and state laws, including the Migratory Bird Treaty Act. Per CPW, no human encroachment is allowed within 150 feet of prairie dog burrows that are being used as nests from March 15 through October 31”. 

The assessment was done in the winter and did not include a burrowing owl survey. The BA recommends a burrowing owl survey.  

ERO Resources Corporation prepared a Prairie Dog Management Plan for BBCP in February of 2020. This plan also recommended surveying for burrowing owls before any prairie dog control and prior to any groundbreaking activity.

Is BBCP planning to do a survey for burrowing owls during the 2021 season?

Not currently. They have not committed to completing a survey during the 2021 breeding season. If a survey is not completed, BBCP, or anyone who destroys the prairie dog habitat during burrowing owl breeding season, risks harming burrowing owls and violating the MTBA and the CO Endangered Species Act.

BBCP released a memo January 2021 from ERO resources stating that no owls were found during a survey conducted in 2020. The results of the 2020 surveys are only valid for the 2020 breeding season. 

How is a burrowing owl survey done?

Colorado Parks and Wildlife (CPW) protocol[xiii] recommends multiple visits during specific times of year and specific times of day because the owls are small and elusive.  The Boulder County Parks and Open Space Burrowing Owl Monitoring Program method ensures that at least one survey occurs within each of four time periods: 15 April-15 May, 16 May-15 June, 16 June15 July, and 16 July-15 August. 

Can citizen scientists help look for owls?

Yes! A volunteer monitoring program is underway! Please  contact LouisvilleSegway@gmail.com  to learn more. BBCP is not allowing public access to the site so we can only survey areas visible from the perimeter of the site.  A map of the 5 major prairie dog towns is in the appendix of the Biological Assessment and  in the Prairie Dog Management Plan. 

Does BBCP have to complete or allow a burrowing owl survey?                                           

No. There is no legal requirement that they look for burrowing owls. However, if they don’t, they, or other parties involved in construction, risk destroying active burrowing owl nests or killing birds in violation of the State Endangered Species Act.

Is it legal for a private landowner to destroy potential burrowing owl habitat?

Yes. While it is illegal to destroy active nests, there is no regulation requiring preservation of burrowing owl habitat. Habitat destruction is occurring all over the state and that is why the owl is endangered. Fortunately, there are many ways to minimize habitat destruction.  

If owls are found is there anything that can be done to protect them?

Yes. If owls are found, consultation with CPW and local agencies is advised. CPW may recommend a habitat conservation plan. There are many measures that a developer can take to preserve habitat for burrowing owls. Grants are available from CPW for habitat protection of state listed species.[xiv]

What can Louisville Residents do?

Louisville residents should encourage the Planning Commission and City Council not to approve a General Development Plan or allow any disturbance to the prairie dog towns on the property until a survey is completed.  

Links for references

[i] May 13 2020 Environmental Update

[ii] Boulder Audubon, and Cornell lab of Ornithology

[iii] State Threatened Species

[iv] State Endangered Species Act

[v] Migratory Bird Treaty Act

[vi] Federal Register document

[vii] CRS 33-2-105 (4).

[viii] State Wildlife Action Plan

[ix] Boulder County Species of Special Concern

[x] City of Louisville Comprehensive Plan

[xi] Biological Assessment

[xii] May 13 Environmental Update, 

[xiii] Protocol

[xiv] Grants