What We Do
Wildlife conservation is at the heart of the National Wildlife Refuge System. It drives everything on U.S. Fish and Wildlife Service lands and waters managed within the Refuge System, from the purposes for which a is established to the recreational activities offered to the resource management tools used. The Refuge System staff manages Service lands and waters to help ensure the survival of native wildlife species.
Crescent Lake National Wildlife Refuge was established as a refuge and breeding ground for birds and wild animals so proper habitat is top priority. Grazing and prescribed fire are two important tools used to maintain habitat quality for nesting and migratory birds. Habitat management supports tall warm season grasses in the meadows while maintaining grassland diversity in the uplands.
To maintain, recover and improve native habitat, Refuge staff use a variety of management techniques including manipulating water levels to foster desired plant growth, prescribed burning, seeding, mowing and experimental bio-control insect releases. Sensitive areas are closed to the public so that the land can recover more quickly. Standardized wildlife and vegetation surveys are conducted on some refuges throughout the year to inventory populations and document habitat use. Units are evaluated by how well they meet habitat and wildlife use objectives. Refuge staff carefully considers all management activities before implementing them, as environmental conditions are constantly changing. Adaptive management is critical to maintaining quality habitat.
More than 99% of native tallgrass prairie has been lost in North America due to agricultural conversion. Undisturbed, tall grass cover is valuable for nesting waterfowl and other species, including grouse, bitterns, northern harriers, short-eared owls, and many songbirds.
Native grasses have root systems between five and nine feet deep; therefore, these grasses provide excellent long-term erosion control. Native grasses also grow well on poor soil because their deep roots can gain access to nutrients and water that shallower roots cannot reach. Native grass stands require several years to reach maturity, and for this reason, mowing is not done on Crescent Lake National Wildlife Refuge.
Management and Conservation
Refuges deploy a host of management tools to address biological challenges. These tools include water management to monitoring to preserve wilderness features, all aimed at ensuring a balanced conservation approach to benefit both wildlife and people. At Crescent Lake National Wildlife Refuge the conservation toolbox includes:
The grassland ecosystem evolved with grazing, primarily by bison, but bison have been replaced on the prairie by cattle. Crescent Lake NWR uses a permit system that allows ranchers to graze their cattle on the Refuge for a fee. A former landowner held the permit until 1942, grazing as they had done with their ranch. After 1942, Refuge managers began reducing the length of grazing or the number of animals, to allow for more rest so that grass cover could recover. By 1980, total length and number of animals had been reduced by over half.
Current grazing practices aim to reach habitat goals for a variety of species. Fall and winter grazing can create short areas of cover in April for the long-billed curlew, but still allow for vigorous plant growth in the spring for nesting waterfowl. Spring grazing reduces invasive grasses and allows open spaces for germination of summer wildflowers for butterflies, bees, and other pollinators. Summer grazing can expose the choppy hills to wind erosion until the next spring to aid in habitat creation for the endangered blowout penstemon.
Historically, fire was a natural and valuable force in the grasslands, and today staff mimic these fires with prescribed burns. Prescribed burning is a tool used by managers to provide many benefits such as plant growth and weed control, which increases habitat for wildlife. Burning reduces woody plant invasion and removes litter buildup that can choke out native plants. Tall grasses such as bluestem, switchgrass, and indian grass are stimulated by a properly timed . When a burn is conducted in early April, early season grasses have already begun to sprout, and will be badly damaged by the fire. However, grasses that come up in the warmer temperatures are still dormant under the ground, and their underground energy reserves are unaffected.
The black ground that results from a burn increases soil temperatures causing native grasses to sprout earlier, enabling them to compete with any invasive grasses that remain. Fall burning is not as effective because it allows invasive grasses to grow after the burn without competition. Burning may also be used to prepare a field for seeding by removing litter and other unwanted growth which then provides good soil for planting native seeds.
Crescent Lake NWR has set up 1200-1800 acre burn units on a five year ration to reflect historical fire intervals.
Water Management Units
Nine units have water management capability which is used primarily to provide forage and resting areas for migrating waterfowl and shorebirds.
Our Projects and Research
Crescent Lake National Wildlife Refuge has a history of conducting and participating in scientific research. For example, Dr. John Iverson and his students from Earlham College (Richmond, Indiana) have been capturing, measuring, individually marking, releasing, and recapturing turtles on the Refuge since 1981.
Crescent Lake National Wildlife Refuge is home to only four turtles: the large and powerful Common Snapping Turtle (Chelydra serpentina), the colorful Western Painted Turtle (Chrysemys picta bellii), the prairie-dwelling Ornate Box Turtle (Terrapene ornata), and the odorous Yellow Mud Turtle (Kinosternon flavescens). Although the turtle diversity is not great, the numbers of each species on the Refuge are phenomenal. The changes in population and reproductive ecology of these turtles has been the subject of one of the longest running scientific field studies in the world.
Dr. Iverson and his team have contributed greatly to our understanding of turtle biology. Some of their findings include:
1) Some turtle species regularly live beyond 50 years of age.
2) A female common snapping turtle once laid 97 eggs in a single nest!
3) Western painted turtle eggs hatch in the early fall but the hatchlings remain in the nest all winter and emerge and migrate to the water in the early spring. These hatchlings commonly experience temperatures as low as 15 degrees Fahrenheit during the winter, but the hatchlings still survive without freezing.
4) Yellow Mud Turtles are the only turtle in the world that nests while completely buried underground.
5) Although considered a land only turtle, ornate box turtles regularly migrate to wetlands (including windmill overflows) to rehydrate.
6) The gender of common snapping turtles, ornate box turtles, yellow mud turtles, and Western painted turtles is determined by the temperature of the underground nest during the middle third of incubation.
The Mission of the Office of Law Enforcement "is to protect wildlife and plant resources. Through the effective enforcement of Federal laws, we contribute to Fish and Wildlife Service efforts to recover endangered species, conserve migratory birds, preserve wildlife habitat, safeguard fisheries, combat, and promote international wildlife conservation."