During the 2015-2016 season, 24 volunteers monitored raptor nesting sites at 22 locations on Boulder County Parks and Open Space properties. Volunteers monitored bald eagle, golden eagle, red-tailed hawk, great-horned owl, osprey, and prairie falcon.
Here is a summary of what our volunteers recorded:
- The earliest recorded date of arrival on territory by a male or female of a mated pair was November 1, 2015 by bald eagles. The latest was March 24, 2016 by a male osprey at Lagerman Reservoir.
- Five bald eagle nests on county open space began incubation in February, with one commencing in March possibly due to extended courtship with a new mate. This was similar to the four bald eagle nests in Boulder County, all of which began incubation between February 12 and February 17, 2016. In total, the nests produced at least 12 young!
- Three osprey nests on county open space properties began incubation in late April.
- Boulder County has over 15 golden eagle nesting territories, with seven nest sites occurring on county open space properties. This year, two of those seven nest sites failed or were inactive, and five nests successfully fledged eight young.
- The greatest number of fledglings (four) produced at a single nest was by a prairie falcon pair at Hall Ranch Open Space.
- A pair of burrowing owls returned to a nest site for the fourth year in a row. The owls successfully reared four young on a diet of toads, mice, and insects.