The eagles have landed: High numbers of bald eagles seen at Lagerman Reservoir

Lagerman Reservoir is a little-known gem of the Boulder County Parks and Open Space system. Well, at least that’s the case for the human residents of Boulder County. It’s a different story for the local and migratory bird communities, and for one bird in particular. This winter bald eagles have turned Lagerman Reservoir into their local stomping ground.

Bald eagles are a well-known success story of the environmental and nature conservation movements. By the mid-20th century the national eagle population had been reduced to less than 500 nesting pairs, due to a variety of human-related causes, including habitat loss, illegal shooting and the effects of the infamous pesticide DDT. The two most important factors in the bald eagle’s recovery were its placement on the then-nascent Endangered Species list in 1967, and the nationwide banning of the usage of DDT in 1972. From that point forward bald eagles began to make a steady comeback, capped by their removal from the Endangered Species list in 2007.

“The last 10 years have seen a growth spurt in the bald eagle nesting population in Boulder County, whereas prior to that there were basically none,” says local bird expert Steve Frye, owner of the Wild Bird Company in Boulder. “We’ve actually seen a slight dip in the number of eagles overwintering here, probably due to the increase in the number of local nesting pairs,” Frye adds, indicating the birds’ territorial nature.

Bald eagles mate for life, and typically maintain the same nest year after year. Nests are usually located near bodies of water, given that fish are the bird’s preferred choice of cuisine. When low wintertime temperatures cause lakes to ice over, however, beggar eagles can’t be choosers. Fry said, “Wintering raptors in Boulder County depend on prairie dog and rabbit populations,” both of which are plentiful in the fields around Lagerman. He adds that waterfowl are also a part of the local bald eagle’s menu, and that overall it’s “probably a more varied diet for the birds here, compared to other bald eagle populations.”

A Sunday afternoon excursion to the reservoir by this reporter saw a total of eight bald eagles in the area, two adults and six fledglings. Another recent trip by longtime Boulder County residents David and Karen Jaeger produced a count of 15, including four adults and 11 birds in the immature phase. Immature bald eagles are easily distinguishable due to their lack of the distinctive crown of all-white head feathers for which bald eagles are so named. The birds were seen roosting in nearby cottonwoods, flying overhead, sitting on the lake shore, and out on the ice in the middle of the lake.

Lagerman plays host to a number of different animal populations during the year. David Jaeger lists mergansers, cormorants, coot, teal, wigeon and northern shoveler among the many waterfowl he’s observed on the lake. Great blue herons can be seen perched in stillness among the reeds, rabbits and prairie dogs are a constant presence in the surrounding pasture and grasslands, and other raptors such as red-tailed hawks and American kestrels frequent the area as well.

With such a vibrant community, good access to locally-sourced food, and unbeatable mountain views, it’s no wonder that bald eagles have chosen to call Lagerman Reservoir home.

Lagerman Reservoir is southwest of the intersection of 71st St. and Clover Basin Drive, northwest of Niwot.