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Boulder Reservoir Wildlife

The reservoir offers a great variety of wildlife viewing opportunities.

Wildlife Guidelines

  • Please do not feed any wildlife.
  • Please obey all seasonal wildlife closures and signs. At different times throughout the year portions of the reservoir may be closed to protect nesting wildlife and habitat.
  • Osprey nests are monitored on the west side of Boulder Reservoir near an area referred to as Windsurfer's Point. Because of the rarity of a successful nest site for this species along Colorado's Front Range, the area around the nesting platform will be closed to human use. This regulatory closure is from Feb. 1 through Sept. 10. The closure area is within 300 yards of the nesting platform on land and within 100 yards of the nest site on the water of Boulder Reservoir. The closure boundaries are marked with signage both on land and on water (buoy markers). Please note that entering this closed area 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. Local, state and federal laws prohibit harassment of osprey and other wildlife around the Boulder Reservoir. Note that all birds of prey, waterfowl and all wildlife species are protected under local, state and federal law.
  • Horses are prohibited at the reservoir.
  • No person shall hunt, trap, net, impede, harass, chase, kill or remove any wildlife or destroy, remove any burrow, nest or animal dwelling.
  • Fishing regulations come under the jurisdiction of Colorado Fish and Game Department. Please see the Colorado Division of 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). The annual Boulder Reservoir Birds of Special Concern Monitoring Summary has been completed and a summary is below:

  • During 2017, 33 volunteers devoted 562 hours to this monitoring effort.
  • Northern Harrier – Boulder County Rare & Declining
    • Another failed nesting attempt at Dry Creek (model airport area)
    • Successful fledging of 3 young at Little Dry Creek; once again the only successful Northern Harrier nest we know of in all of Boulder County this year.
    • Based on recent observations, Northern Harrier appears to be among the most endangered nesting bird species in Boulder County (see Hallock and Jones 2010). Therefore, every effort should be undertaken to protect and expand potential nesting areas.
  • American Bittern – Boulder County Isolated and Restricted
    • During 2017 we saw or heard American Bitterns at eight locations around the Reservoir.  Confirming nests or fledged young is difficult for these elusive birds; however, it is believed that at least some were successful this year.
    • In Boulder County the species is still limited to only about a dozen documented nesting sites, and eight of these are in wetlands adjacent to Boulder Reservoir, privately-owned Six-Mile Reservoir, and Coot Lake. 
    • Given their vulnerability to urban-adapted predators and proximity to recreation, strategies that increase the size of marshes and protect them from disturbance by humans and pets should benefit nesting bitterns.
  • Osprey – Boulder County Isolated and Restricted
    • Little Dry Creek failed for the first time and Dry Creek area nest failed again.  Causes are unknown.
  • Burrowing Owl – Boulder County Isolated and Restricted
    • Burrowing Owls had not been documented nesting successfully within the study area since 2004 nor even observed since 2011; however, this year 2 out of 4 young successfully fledged from the Dry Creek area. 
    • 2017 appears to have been the most productive year for nesting Burrowing Owls in Boulder County during this century (Jones).
    • Protection and conservation of prairie dog colonies around the reservoir may contribute to future burrowing owl nesting success, especially if prairie dog colonies are relatively large and buffered from disturbance.
  • Between March and August, we observed a total of 91 bird species within the study area, including 71 potential breeding species.  This is considerably more potential nesting species than volunteers observed during the previous two years; the increase is probably due to increased training of volunteers in ways to determine potential nesting, along with increased volunteer effort.  Nesting was confirmed for 13 species. However, birds observed during 2017 included only 10, instead of last year’s 13, Boulder County or Colorado Natural Heritage Program listed species (Colorado Natural Heritage Program 2016, Hallock and Jones 2010).

The full report pdf includes known disturbances or closure violations and detailed recommendations for management actions, including limiting human use, in each closure area.  

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