Reports

Limited Availability of Old Growth Cottonwood Nest Trees in the Northern Colorado Front Range
By Dana J. Bove (Front Range Nesting Bald Eagle Studies)

The limited availability suitable old-growth or Plains Cottonwoods for bald eagle nests in areas of the northern Colorado Front Range (NCFR)—and specifically those at a sufficient distance from anthropogenic disturbance—has received little attention when it comes to protection of territorial bald eagles and their habitat in Colorado. Although a common assumption is that alternate nest trees should be easy for bald eagles to acquire, this is arguably not the case across the NCFR.

READ REPORT (PDF — October 5, 2022)

Stahlecker, D.W., 2020. Statement for Boulder County Parks and Open Space Concerning bald eagles in relation to revised management plan for the Carolyn Holmberg Preserve at Rock Creek Farm (CHPRCF). Unpublished report prepare for FRNBES.

The Carolyn Holmberg Preserve open space, in Boulder County, just southeast of Boulder, could offer a safe haven for a pair of nesting bald eagles that have been dogged by development in adjacent Broomfield County since 2013. During fall of 2019, the Stearns bald eagles moved about 1 kilometer from their old nest site to the Holmberg Preserve, following nearly two years of continuous home construction at their former nest site. One might think that the nearly 1,200-acre Holmberg Preserve would provide the perfect alternative nesting site for the Stearns eagles. However, natural resources, burgeoning trail usage, and land management priorities have put the odds of nesting success for this well-loved bald eagle pair in serious jeopardy.

READ REPORT (PDF — 13 July 2020)

Expert Opinions and Conclusions Concerning the U.S. Fish and Wildlife Service’s “Take” Permit MB663S7C-O (project AR1237-39), Garrett Construction Co., Impacting the Stearns Bald Eagle Nest. Broomfield. Colorado

State wildlife managers at Colorado Parks and Wildlife (CPW) have publicly expressed concerns about “densely [human] developed areas [in the NCFR corridor] that also contain a high concentration of bald eagles”. This appears to have led to a new management definition applicable to bald eagle nests located in “highly developed areas” (Colorado Parks and Wildlife 2020). Nests in “highly developed” areas are defined by CPW as those occurring in “an area where the existing [building] density exceeds 10 or more daily occupied facilities within a ¼ mile (1320 feet, 400 m) radius of the nest.” Instead of the previous no surface occupancy recommendation (NSO) aimed at protecting all bald eagle nests year-round at ½ mile seasonal or ¼ mile annual radius (Colorado Parks and Wildlife 2008), a new NSO buffer of 660 ft (400 m) now applies to nest territories deemed as “highly developed” (Colorado Parks and Wildlife 2020). Colorado Parks and Wildlife’s new 660 ft buffer for these purportedly urbanized nest territories is derived from U.S. Fish and Wildlife’s bald eagle management guidelines, which have long-recommended 660-foot radius buffers around bald eagle nests (U.S. Fish and Wildlife Services 2007).

The 660-ft nest buffer adopted from USFW guidelines can be traced to studies conducted nearly 25 years ago on impacts of timber clearcutting in dense northern boreal forest habitats around bald eagle nests (Manville 2018).

READ REPORT (PDF — April 10, 2018)

Home Range and Critical Areas for Bald Eagles at Standley Lake
Submitted to the City of Westminster
Colorado Bird Observatory / 13401 Piccadilly Road / Brighton, CO 80601

Due to the steep decline of bald eagle populations from DDT through much of North America after the early 1940s, bald eagles were rarely noted in the Front Range until the early 1980s. The first documented bald eagle nest in the NCFR was established at Barr Lake in 1986 (Colorado Parks and Wildlife 2020), followed by Standley Lake in 1993. Please see the attached 1993 report by the “Colorado Bird Observatory” or now called Bird Conservancy of the Rockies.

READ REPORT (PDF — April 10, 1993)