Northern Harrier Circus cyaneus Habitat Preference Large tracts of undisturbed open grasslands with thatch used for nesting cover Threats Northern harriers are a late successional grassland ID: 287861
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Developed by the Iowa Department of Natural Resources through the Landowner Incentive Program in partnership with the US Fish and Wildlife Service. Northern Harrier Circus cyaneus Habitat Preference: Large tracts of undisturbed, open grasslands with thatch used for nesting cover. Threats: Northern harriers are a late successional grassland species. Haying an area during nesting season destroys nests. Northern harriers will not use grasslands that are grazed heavily; even light grazing during the nesting season can destroy nests. Loss of grassland habitat Conversion of prairie to cultivated ground Encroachment of woody vegetation. Northern harriers will not nest in areas that have trees scattered throughout the grassland. Invasion of non-native plants Fragmentation of grassland habitat Because northern harriers need large (+100 acres) undisturbed grassland tracts, they require plenty of refuge from disturbance such as fire and grazing. These birds will cease to use tracts when large sections are managed in a variety of ways not conducive to this sparrows nesting. Practices Guidelines: Prescribed burns should be done no more than once every 4 years. Burns should not be done during the nesting season (April-July). Harriers will not nest in an area that has been burned during that nesting season. Limit water manipulation. In areas known to be used for nesting water depths should be kept below 15 cm. Repeated haying will deter nesting use by northern harrier. Haying should not be done until after July 15. Mowing on established areas should be done after the nesting season (April-July). Areas that are lightly grazed may still be used by northern harriers. Limit grazing to after the nesting season (April-July). Establish new tracts of grassland. Buffer existing grassland to create larger tracts that will sustain a large population of rodents. When rodent populations are high northern harriers are more apt to use a particular area.