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Colorado IBAs
John Martin Reservoir State Wildlife Area
Bent County
Size: 27,000 acres
Elevation: 3800 feet
Habitats:
Primary – open water
Secondary – shore/bank, grassland, lowland riparian, sagebrush shrubland
Ownership:
Federal (U.S. Army Corps of Engineers)
State (CO Division of Wildlife)
Land Use:
Primary – nature and wildlife conservation, water supply
Secondary – hunting/fishing, recreation/tourism, undeveloped
IBA Criteria: 1, 2, 3, 4 (waterfowl, heronries, shorebirds, gulls, terns, raptors, landbirds)
Site description
Location:
John Martin Reservoir State Wildlife Area is located on the Arkansas River near the town of Hasty in southeastern Colorado.
Vegetative/natural features:
The site contains a flood control and irrigation reservoir that ranges in size from a low of 1,000 surface-acres up to a high of 15,000 surface-acres, with an average size of 8-9,000 surface-acres. Habitat types include shoreline, upland sage, shortgrass prairie, riparian woodlands, mudflats, and islands.
Ornithological Importance
For the past 7 years, this site has been the most important nest site in Colorado for Least Terns and Piping Plovers. Upland sage habitat supports Cassin’s and Lark Sparrows, and there is a heron rookery on the west end.
Breeding species:
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Average #
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Maximum #
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Piping Plover
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1-4 pairs
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13
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Least Tern
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1-20 pairs
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20 pairs
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Snowy Plover
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2-4 pairs
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10
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Burrowing Owl
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10 pairs
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Ferruginous Hawk
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1 pair
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Western Grebe
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0-100 pairs
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Clark’s Grebe
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0-100 pairs
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Swainson’s Hawk
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5 pairs 5 pairs
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Migrant species:
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Average #
|
Maximum #
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Peregrine Falcon
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~10 (spring, fall)
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American White Pelican
|
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200-1,000 (spring, fall)
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Long-billed Curlew
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>100 (spring, fall)
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Western Grebe
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|
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Clark’s Grebe
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0-100 pairs (spring, fall)
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Prairie Falcon
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0-100 pairs (spring, fall)
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4 (spring, fall)
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Conservation/Management Issues
Serious threats:
- invasive plants (cottonwoods invading beaches);
- predators (mammals, snakes, grackles, gulls);
- disturbance to birds;
- hydrologic changes (habitat is susceptible to flooding).
Potential threats:
Efforts to address threats:
Land managers periodically clear the island vegetation to provide better nesting habitat, and reduce mammalian and snake depredation. Colorado Division of Wildlife institutes periodic closures to protect nesting birds.
Management details:
The Army Corps of Engineers owns the bulk of the reservoir shoreline, but leases most to Colorado Division of Wildlife.
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