Bonny Lake State Park

Background | Criteria | Northwest Colorado | Northeast Colorado
Southwest Colorado | Southeast Colorado

Bonny Lake State Park & South Republican Management Area
Yuma County

Size: ~4,000 acres (Bonny Lake State Park)

7.5 miles long (South Republican Management Area)

Elevation: 3310 - 3782 feet

Habitats: Primary – lowland riparian, open water

Secondary – grassland, wetlands

Ownership: State (State Parks, CO Division of Wildlife)

Land Use: Primary – recreation/tourism, hunting/fishing, nature and wildlife conservation

IBA Criteria: 3, 4 (waterfowl, landbirds)

Site description

Location: Bonny Lake State Park is located 8 miles south of Idalia and 20 miles north of Burlington. South Republican Management Area is immediately east of Bonny, and extends 7.5 miles east to the Kansas state line.

Vegetative/natural features: Bonny Lake State Park contains a variety of marsh, woodland, and prairie habitats. Bonny Lake, a 2,000-surface acre reservoir, covers approximately half the park and lies in the South Fork of the Republican River. Cottonwood/box elder stands, shelter belts, and remnant farm plantings line the reservoir and river. The park contains several extensive cattail marshes. Upland grasslands include loess prairies known as the "Bonny Prairie Natural Area," which the Colorado Native Plant Society regards as a good example of untrammeled prairie. Dominant species of the loess prairie include little bluestem, sideoats and blue gramma, purple threeawn, switchgrass, western wheatgrass, needle-and-thread grass, and buffalograss. A shrubland of rabbitbrush and sandsage grows on the south side.

Below the dam, the river flows out through a mixed cottonwood/boxelder woodland into the South Republican Management Area. The Area extends from the edge of the park eastward 7.5 miles to the Kansas state line. The river flows through cottonwood/box elder stands for most of the distance. Colorado Division of Wildlife constructed several ponds at the lower end as wildlife habitat. The area also includes a few cattail marshes, some grassland, fields planted in grains attractive to wildlife, and a shrubland of rabbitbrush and sandsage.

Ornithological Importance

Located amid dry prairie and monoculture farmland, this site provides a well-protected riparian ecosystem. Found on the fringe of the migration corridor for eastern landbirds, it attracts a large variety of migrant species including many that are rare in the rest of Colorado. It is one of the few public areas in Colorado that hosts a contingent of breeding eastern species. Substantial numbers of waterfowl migrate and spend the winter at the site. The park’s bird list includes approximately 279 species.

Bonny Lake State Park

Breeding species:	Average #	Maximum #
Bell’s Vireo	5-10 pairs
Cassin’s Sparrow	10
Yellow-billed Cuckoo	5
Western Wood-Pewee	25
Loggerhead Shrike	5
Lark Sparrow	25
Grasshopper Sparrow
Dickcissel	5	25-50
Lark Sparrow	50
Grasshopper Sparrow	50
Lark Bunting	50
Yellow-headed Blackbird	100
Orchard Oriole	100
Eastern specialties
Red-bellied Woodpecker	5
Red-headed Woodpecker	25
Northern Yellow-shafted Flicker	25
Baltimore Oriole	25

Wintering species:	Average #	Maximum #
Mallard	19,643	35,000
All ducks	19,810	35,209
All waterfowl	20,227	35,750

South Republican Management Area
Breeding species:	Average #	Maximum #
Great Blue Heron	heronry of unknown size
Cassin’s Sparrow	25
Yellow-billed Cuckoo	5
Western Wood-Pewee	25
Dicksissel	5-10	25-50
Lark Sparrow	100
Grasshopper Sparrow	50
Lark Bunting	100
Orchard Oriole	25
Eastern specialties
Red-headed Woodpecker	25
Northern Yellow-shafted Flicker	25
Great Crested Flycatcher	1-5
Eastern Bluebird	10
Baltimore Oriole	25

Research and educational activities: Bonny Lake State Park contains a short self-guided nature trail through a shortgrass prairie area.

Conservation/Management Issues

Minor threats:
1. disturbance to birds from boat use on the lake and recreational use on land.

Potential threats:
1. pollution from runoff from agricultural lands upstream.

Management details:
Colorado State Parks manages Bonny Lake State Park, while the Colorado Division of Wildlife oversees the South Republican Management Area. Both are Colorado Watchable Wildlife sites.