- Do not feed any wildlife.
- Obey all closures and signs. At different times throughout the year portions of the reservoir may be closed to protect nesting wildlife and habitat.
- Osprey, American bittern, northern harrier and burrowing owl nests are monitored on the west side of Boulder Reservoir and at Coot Lake. Because these are species of concern, the areas are closed to human use. This regulatory closure is from March 15 through Sept. 10 (or Oct. 31 for burrowing owls). The closure area includes water space at the Boulder Reservoir. The closure boundaries are marked with signage both on land and on water (buoy markers).
- Local, state and federal laws protect wildlife around the Boulder Reservoir.
- Entering closed areas may result in a summons to court (fines of up to $1,000 and/or 90 days in jail) and suspended boating privileges at the Boulder Reservoir.
- No person shall hunt, trap, net, impede, harass, chase, kill or remove any wildlife or destroy, remove any burrow, nest or animal dwelling.
- Horses are prohibited at the reservoir.
- Fishing regulations follow all state parameters. Please contact Colorado Parks & Wildlife for more information.
Birds of Concern
The marshes and grasslands surrounding Boulder Reservoir support more nests of Boulder County birds of special concern than any other comparably sized area in the county (Hallock and Jones 2010; Jones 2019). Boulder Parks and Recreation Department volunteers have monitored nesting activities of birds of concern within Parks and Recreation properties surrounding the reservoir and Coot Lake since 2004. During 2021, 23 observers (18 volunteers and 5 staff) participated, with volunteers devoting at least 223 hours to the monitoring effort. The annual Boulder Reservoir Birds of Special Concern Monitoring Report has been completed and a summary is below.
American Bittern - Boulder County Isolated and Restricted
During 2021 we saw or heard American bitterns at six locations within the study area: the Coot Lake wetland, Dry Creek wetland immediately north of the Anthill, the cattail marsh east of the model airplane runways and south of Dry Creek, the cattail marsh east of the Anthill; and the Little Dry Creek wetland east and west of North 51st Street.
We observed no evidence of successful nesting in these marshes during 2021 but did observe as many as four American bitterns flying together over the Little Dry Creek marsh in late July, suggesting that some young had fledged. Our monitoring protocols, which discourage volunteers from approaching within 200 m of suspected nests, make it difficult to confirm successful nesting in dense cattail marshes.
American Bitterns near Boulder Reservoir
|Number of Years (2004 - 2021)|
|Wetland Area||Territories||Nest with Young||Calling or Pair Seen||No Indication||Fledged Young|
|Little Dry Creek||6||1||9||2||3|
Northern Harrier – Boulder County Rare and Declining
A successful nest in the Little Dry Creek marsh was the eighth in this location between 2004-2021. An attempted nesting within the Dry Creek marsh failed during early June.
Northern Harriers near Boulder Reservoir
|Number of Years (2004 - 2021)|
|Wetland Area||Nest Success||Nest Failure||Pair Seen - no nest||No Indication||Fledged Young|
|Little Dry Creek||8||5||1||5||29|
Osprey - Boulder County Isolated and Restricted
Two Osprey nests within the study area fledged a single young during 2021.
Number of Osprey Fledglings near Boulder Reservoir
|Nest Platform Area||2005-2010 (6 years)||2011-2016 (6 years)||2017-2021 (5 years)|
|Little Dry Creek||8||12||1|
Bald Eagle - Boulder County Isolated and Restricted
We observed two adult and two juvenile bald eagles perching within the Dry Creek and Little Dry Creek drainages and near Coot Lake throughout April, May, June, and July, but we noted no signs of nesting.
Burrowing Owl – Boulder County Isolated and Restricted
We observed no burrowing owls within the study area during 2021. We last observed nesting within the study area in 2017, when a nest southwest of the aeromodeling facility fledged three young. We observed a single adult burrowing owl perching on this same nest burrow for less than a week in April, 2018.
Other Breeding Bird Observations
Between 20 March and 30 August, we observed a total of 81 bird species within the study area, including 68 potential breeding species (birds seen or heard within documented nesting habitat during their documented breeding season. Wickersham 2016). Nesting was confirmed for 19 species.
We conducted more comprehensive breeding bird surveys during 2013 when we observed 113 bird species within the study area during April-August, and during 2018 when we observed 108 species during a similar time period (Jones 2013a and 2018b).
The full report includes known disturbances or closure violations and detailed recommendations for management actions, including limiting human use, in each closure area.
An additional study of winter roosting behavior for Northern harriers, bald eagles and short-eared owls was performed and the report notes a high rate of Northern harrier activity.