Northern Harrier

Circus cyaneus

Although a common migrant in open grassland habitat, the Northern Harrier is listed in Missouri as an Endangered breeding species. This species forages and nests in both wet and upland grasslands with some woody vegetation intermixed (almer 1988). Widmann (1907), encouraged farmers "to give, at least on his own grounds, "the fullest protection to a benefactor that removes the pest which eats his grain and girdles his fruit trees". During the mid-1900s, Northern Harrier populations suffered great losses due to pesticide-related egg shell thinning and losses of wetland nesting habitat (Terres 1987).

Code Frequency

Wandering, non-breeding Northern Harriers occasionally appear throughout the summer months (Robbins and Easterla 1992). Therefore, a sight observation of a bird does not necessarily indicate breeding. Observation of harriers usually led to a more intensive search to confirm breeding. For example, when an adult male and an adult female were present in the same vicinity, some Atlasers intensified nest searches in an attempt to confirm breeding. Confirmed breeding reports occurred in 1989, 1990 and 1992 within Atlas blocks.

Distribution

Observations were made statewide, however, most confirmations were in the Osage Plains Natural Division and the Western Glaciated Plains Natural Section. Several public prairies in the Osage Plains Natural Division hosted pairs of Northern Harriers. Most Atlasers reported finding this species in grasslands, both native prairie and non-native pastures, and hayfields.

Phenology

Northern Harriers are common migrants in Missouri from February to May, and again from August to November (Robbins and Easterla 1992). They nest fairly late in the season. As a ground-nesting species, they require new growth to conceal their nest location, which may explain the late nesting season.

Notes

During the Atlas Project, land enrolled in the Conservation Reserve Program provided additional nesting and foraging habitat for Northern Harriers.

Breeding Evidence

Reported in 33 (2.7%) of 1,207 blocks

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