Research Data | Boulder County Nature Association

BCNA CITIZEN SCIENCE RESEARCH AND RESULTS

Wintering Raptor Survey

Since 1983 Boulder County Nature Association (BCNA) volunteers have counted wintering raptors along survey routes scattered throughout the plains of Boulder County, Colorado. We initiated the surveys during a time when intensified poisoning efforts by private landowners and government agencies appeared to threaten prairie dog populations in parts of Boulder County. Some of these poisonings were occurring in the Boulder Reservoir area, where Ferruginous Hawks, Red-Tailed Hawks, and Bald Eagles gathered each winter. We wanted to observe the effects of fluctuating prairie dog populations on these and other species. We also hoped to locate wintering raptor concentration areas, such as Bald Eagle roosts, Northern Harrier roosts and large prairie dog colonies, so that these areas could be protected.

At present, data is submitted to Boulder Country, and Boulder County has the detailed records of all observations.

Populations and Prey Selection of Wintering Raptors in Boulder County,Colorado. 1989. Stephen R. Jones. North American Prairie Conference
Wintering Raptor Population Totals in Boulder County, 1990-2011 (pdf)
Raptor population trends for Boulder County by species combining survey data from all locations, 1990-2011 (pdf)
Population trends of common raptors (red-tailed hawk, ferruginous hawk and rough-legged hawk) for each of the three survey transects with longterm data, 1990-2011 (pdf)
Population trends of uncommon raptors (bald eagle, golden eagle and northern harrier) for each of the three survey transects with longterm data, 1990-2011 (pdf)
Spreadsheet with full 1990-2011 data set (.xls file)
Wintering Raptor Populations in Boulder County, 1983 – 1996 (pdf)
2018-2019 wintering raptor survey results and summary data from 1990-2019 (pdf)
Wintering Raptor Spreadsheets: Summary data for all routes, 1990-2012,2014-2016 and data for individual routes, 1990-2012 (.xls file)
2019/2020 Wintering Raptor Survey data by observer for all routes (.xsls file)
2020 Wintering Raptor Survey summary data with graphs of routes and species for prior years (pdf)
2021-22 Boulder County Wintering Raptor Survey Summary

Boulder County Avian Species of Special Concern

The Avian Species of Special Concern list attempts to red-flag those species in Boulder County that are of interest due to their rareness, probable decline, and habitat or locational restrictions. Hence, they are more vulnerable and less adaptable to change. It is based on a comparison of historic and current records, studies, and lists that are felt to represent the best available information. The list primarily focuses on breeding status. In addition, the list utilizes regional, state and local assessments.

Status of Nesting Golden Eagles in Boulder County and Adjacent Areas of the Front Range in Colorado: A Preliminary Report Mike Figgs and Nancy Lederer, May 15, 1985
Ecology, status and avifauna of willow carrs in Boulder County Dave Hallock, Nancy Lederer, and Mike Figgs. Boulder County Nature Association Publication No. 4. January 1986
Boulder County Avian Species of Special Concern Dave Hallock and Stephen R. Jones, 1999
Boulder County avian species of special concern Hallock, Dave, and Stephen Jones, 2010
State of the Birds in Boulder County: 2011 Report Stephen Jones, September 3, 2011

Butterflies in Boulder County

BCNA funded the 2007 continuation of a research program to survey Boulder County butterflies and preparation of a 74-page report. Surveys in 2004-06 were funded by the Boulder County Parks and Open Space Small Grants Program. Since then, monitoring of the butterflies in Boulder County has been funded by both the Boulder County Parks and Open Space Small Grants Program and BCNA. Links to later reports (PDF) on the Boulder County Web site are also given below.

Report for 2004-2007
Summary of 2007-2011 butterfly data
Summary report of butterfly observations on the Ann U. White trail before the September 2013 floods
Other butterfly reports are published on the Boulder County website.

Butterfly counts have been held at the Cal-Wood Education Center every July 4 for 29 years, 1984-2012. A 29 page report covering those 29 years is now available as a PDF (3.8 MB)

Fourth of July Butterfly Counts 1984-2012

Both the Colorado Front Range Butterflies website and the book, Butterflies of the Colorado Front Range by Janet Chu and Stephen Jones stem from research partially supported by BCNA.

Indian Peaks Bird Counts

The Indian Peaks Four Season Bird Counts started in 1982 in order to inventory the avifauna of western Boulder and northwestern Gilpin counties in Colorado. These counts provide information about species presence and relative abundance as well as documenting trends and composition changes occurring in the mountain landscape.

History, information, and summary of results of the Indian Peaks Bird Count

Allegra Collister Bird Banding Project

Allegra Collister, a co-author of A List of Birds of Rocky Mountain National Park, began banding birds in a small gulch north of Boulder in 1950. Since then, a small group of volunteers have continued the effort; over 10,000 birds and over 180 species have been banded, or sighted in this small gulch measuring a quarter mile long and 300 yards wide. In 1992, James Guercio donated a Conservation Easement covering the area historically used for bird banding by Allegra Collister and BCNA volunteers to BCNA. The Allegra Collister Nature Preserve came into being at this time. In 2011, the Conservation Easement was transferred to Boulder County Parks and Open Space. BCNA, however, retains one-half of all mineral rights within the Allegra Collister Nature Preserve and pays a small tax assessment on them each year. Bird banding is continuing each spring with Maggie Boswell, a licensed bird bander, and volunteers. This banding is under the aegis of the national Bird Banding Laboratory in Laurel, MD and the Rocky Mountain Bird Observatory.

Data reports for this project

Burrowing Owl Monitoring

Since 2007, BCNA has recruited volunteers to monitor prairie dog colonies on Boulder County Parks and Open Space properties for nesting burrowing owls. The purpose of this study is to locate burrowing owl nests, determine the rate of nesting success, and devise strategies for protecting and enhancing nesting areas.

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