Plants and Animals
Circus hudsonius Northern harrier
Northern harriers are slim bodied, long-legged and long-tailed hawks. Average harrier length is 17-23 inches (43-58 cm) and the wingspan averages 38-48 inches (96.5-122 cm). They are a sexually dimorphic species in respect to both size and color. Females are heavier and larger than males. The female is brown above and buff-colored with brown streaks below. The male is pale gray above and white below with black outer primary feathers. The white patch at the base of the tail is distinctive for adults and juveniles of both sexes. In flight, harriers usually fly just above the ground with only periodic heavy wing beats, banking and gliding slowly over open habitats. Vocalizations include an alarm or excited call usually described as "ke-ke-ke" or "chek-ek-chek-ek".
Status and Rank
State Status: SC - Special Concern (rare or uncertain; not legally protected)
Global Rank: G5 - Secure
State Rank: S4 - Apparently secure
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Information is summarized from MNFI's database of rare species and community occurrences. Data may not reflect true distribution since much of the state has not been thoroughly surveyed.
Harriers nest and hunt in a variety of open habitats dominated by herbaceous vegetation. Large patches of suitable habitat are important to this ground-nesting raptor.
Natural Community Types
For each species, lists of natural communities were derived from review of the nearly 6,500 element occurrences in the MNFI database, in addition to herbarium label data for some taxa. In most cases, at least one specimen record exists for each listed natural community. For certain taxa, especially poorly collected or extirpated species of prairie and savanna habitats, natural community lists were derived from inferences from collection sites and habitat preferences in immediately adjacent states (particularly Indiana and Illinois). Natural communities are not listed for those species documented only from altered or ruderal habitats in Michigan, especially for taxa that occur in a variety of habitats outside of the state.
Natural communities are not listed in order of frequency of occurrence, but are rather derived from the full set of natural communities, organized by Ecological Group. In many cases, the general habitat descriptions should provide greater clarity and direction to the surveyor. In future versions of the Rare Species Explorer, we hope to incorporate natural community fidelity ranks for each taxon.
With habitat loss the major threat to Northern harrier populations, habitats used on the nesting and wintering grounds need to be preserved. The focus of this preservation should be where large tracts of suitable habitat already exist. Conservation easements, continuation in the Conservation Reserve Program of the Farm Bill, purchases of new acreage, and law enforcement are important tools to aid in preservation of harrier habitat. In managed wetland areas, water levels should be kept low (< 6 in.) during the nesting season to prevent nest inundation and elimination of the prey base. Another management option for grassland habitats is periodic burning. Burning every few years outside of the nesting season helps to prevent succession and encroachment of woody vegetation. Lastly, nest visitations and disturbances should be avoided. In areas where human disturbances could potentially threaten nesting Northern harriers, the creation of buffer zones surrounding nest sites is a possible solution. Agricultural practices such as repeated mowing or heavy grazing can destroy nests and cause birds to abandon otherwise suitable habitat. Harriers also are sensitive to human and agricultural activity. Human presence near the nest sites may cause birds to desert their nest.
Migration from fourth week of March to fourth week of April
Nesting from fourth week of April to third week of July
Migration from third week of August to third week of November
Survey methods include observations of a food pass from the male to the female, which often indicates an active nest. Also, observation of a hunting female during the nesting season requires searching near the area of observation, as they stay close to the nest site while hunting. Lastly, presence of young birds in close proximity to adults may indicate a nest site. Once nesting is confirmed or is deemed highly probable survey personnel should leave the area immediately. Any monitoring of activity near the nest should be done from afar.
Observation during nesting
Survey Period: From first week of May to fourth week of July
Time of Day: Morning (after sunrise)
- Bibby, C.J., N.D. Burgess, and D.A. Hill. 1992. Bird Census Techniques. Academic Press, New York.
- Currier, C. 2001. Special Animal Abstract for Circus cyaneus (Northern harrier). Michigan Natural Features Inventory, Lansing, MI. 5pp.