Circus hudsonius, northern harrier
Snyder, S. A. 1993. Circus hudsonius, northern harrier. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: https://research.fs.usda.gov/feis/species-reviews/cihu
| Abbreviation | Common Name | Scientific Name | Classification | Status |
|---|---|---|---|---|
| Animals | ||||
| CIHU | northern harrier | Circus hudsonius | Life Form: Animals/Bird Kingdom: Animalia Class: Bird Order: Falconiformes Family: Accipitridae Genus: Circus | Fed. Protected: No Nativity: Native Invasiveness: Noninvasive |
Taxonomy
The scientific name of northern harrier is Circus hudsonius (Linneaus) [25]. There are three subspecies of northern harrier, but only one of these, C. hudsonius hudsonius (Linnaeus), inhabits North America [16].
Synonyms
- Circus cyaneus Linneaus [1]
Other Common Names
marsh hawk, blue hawk, white-rumped harrier, cinereous harrier, frog hawk
General Distribution
The northern harrier has a circumpolar distribution. In North America, it is found from north Alaska east across Canada to the Atlantic Coast, and south to Mexico [8,16]. It breeds from the northernmost part of its range through the central states, and winters in the southern states. Some populations are year-round residents [16].
States and Provinces
- United States: AL AK AZ AR CA CO CT DE FL GA ID IL IN IA KS KY LA ME MD MA MI MN MS MO MT NE NV NH NJ NM NY NC ND OH OK OR PA RI SC SD TN TX UT VT VA WA WV WI WY
- Canada: AB BC MB NB NF NT NS ON PE PQ SK YT
- Mexico
Plant Communities
Northern harriers inhabit wetland plant communities of sedge (Carex spp.), rush (Juncus spp.), reed (Phragmites spp.), bulrush (Scirpus spp.), willow (Salix spp.), and tamarisk (Tamarix spp.) [6,16].
Biological Characteristics
Female northern harrier.
Development and Reproduction
- Age of Maturity - 1 year
- Mating/Nesting - March through June beginning in the south and moving north; can mate for life, but sometimes males are polygamous; can nest 4 pairs/sq mile in good habitat
- Clutch - 4 to 6 eggs
- Incubation - 24 to 39 days
- Fledge - 30 to 35 days
- Life Span - 12 years
- Migration - move north beginning in February; move south by late November [7,9,16]
Predators
Predators of northern harriers include red fox (Vulpes vulpes), striped skunk (Mephitis mephitis), raccoons (Procyon lotor), feral cats (Felis domesticus), mink (Mustela vison), and ravens, crows, and magpies (Corvids) [21].
Habitat
Diet
The primary prey base of northern harriers is meadow voles (Microtus pennsylvanicus) [8,16]. They also eat a variety of amphibians, reptiles, and invertebrates when these food sources are abundant [16]. Other prey includes hares (Lepus spp.), rabbits (Sylvilagus spp.), shrews (Sorex spp.), ground squirrels (Spermophilus spp.), lesser prairie chickens (Tympanuchus pallidicinctus), passerine birds, and occasional carion [7,14,16].
Northern harrier in flight at Nantucket National Wildlife Refuge, Massachusetts.
Preferred Habitat
Northern harriers prefer sloughs, wet meadows, marshlands, swamps, prairies, plains, grasslands, and shrublands [8]. They nest on the ground, usually near water, or in tall grass, open fields, clearings, or on the water. In the latter case, nests are built on a stick foundation, willow clump, or sedge tussock [8]. Northern harriers prefer low perches such as fence posts or stumps. For hunting, they use large forest openings. They occur from sea level to 10,400 feet (3,200 m) in elevation [17].
Cover Requirements
Northern harriers need open, low woody or herbaceous vegetation for nesting and hunting [8]. Harriers usually nest adjacent to hunting grounds and where nest predation is low. Their food base should be within 11.2 miles (18 km) of their nests [21]. They use disproportionate amounts of rank grasses, sedges (Carex spp.), willows (Salix spp.), goldenrod (Solidago spp.) and nettle (Urtica spp.) for nest building relative to the abundance of those plant genera [16]. In Massachusetts, northern harriers nest in mixed stands of shining sumac (Rhus copallina), Virginia rose (Rosa virginiana), pasture rose (R. carolina), northern arrowwood (Viburnum recognitum), and highbush blueberry (Vaccinium corymbosum) [5].
Fire-caused Mortality
Fires during the nesting season can destroy northern harrier nests [18].
Fire Effects on Habitat
Fires can open up grasslands and expose prey for northern harriers [2]. However, northern harriers were not observed following prescribed fires in a dry prairie grassland in Florida. The authors admit that counts for large birds may have been underestimated. Fires were conducted in January and again in late June. After the June fire, total bird abundance for all species was lower on the burned site than on the unburned control [12].
Prescribed fire in North Dakota destroyed three of four northern harrier nests, while one nest hatched following the fire [18]. No nests were initiated afterwards. Burning was conducted in mid-June using a backfire on the downwind side followed by flank fires, and a headfire across the upwind side.
To determine the effects on small mammal populations, fires were prescribed on Malheur National Wildlife Refuge, Oregon, where northern harriers are abundant [6]. Fires in early November removed cover and immediately reduced the small mammal population. However, small mammals returned to burned sites the first and second postfire years. There was an increase in small mammal numbers to above preburn levels during the second postfire year, but this might have been due to above-average winter temperatures.
Three years following prescribed burning in Wyoming, northern harriers were not found on unburned plots or on plots burned in early June. Northern harriers were found, however, on plots burned in late August. Small mammal densities were high on the August-burned plots, and raptors were observed preying upon the mammals. The prescribed burning involved two fires, both conducted in a mountain big sagebrush (Artemisia tridentata ssp. vaseyana) community. The first fire, set in early June, resulted in patches of completely burned, partially burned, and unburned areas. Plant cover on plots burned in June was 50 percent lower than on control plots at the first postfire year. Cover was 79 percent of the control by the third postfire year. The second fire was set in late August, and all living and dead vegetation was consumed. Cover on August-burned was 82 percent less than on control plots at the first postfire year, and 54 percent of control plots by the second postfire year.
Fire Regimes
For fire regime information, search FEIS for this species by entering the species name on the Advanced Search page and selecting “Fire Regime” as the publication type.
Fire Management Considerations
When considering controlled burning in wetland areas with ground nesting northern harriers, it is best to either leave partial burns or conduct burning after young have fledged in order to maximize recruitment of this species [18].
Federal Status
None
Other Status
The northern harrier declining due to draining of wetlands, livestock grazing, flooding, and monocultural farming [11,15]. It is noted on The Blue List as down or greatly down throughout most of its range [24]. It is state-listed as endangered in Rhode Island and Illinois and threatened in Massachusetts [5,22,23].
Other Management Information
Northern harrier nests are often trampled by grazing cattle. Suggestions for limiting livestock impact on nesting success include: fence off nesting areas from livestock, provide more watering sites to prevent congestion near nests, and reduce stocking rates [3]. Livestock grazing and haying can also reduce the small mammal population on which northern harriers depend [6].
Table A1— Forest and range ecosystems, Bureau of Land Management (BLM) physiographic regions, Kuchler plant associations, Society for American Foresters (SAF) forest cover types, and Society for Rangeland Management (SRM) rangeland cover types in which this species occurs.
Forest and Range Ecosystems (Garrison et al. 1977)
- FRES19 Aspen-birch
- FRES29 Sagebrush
- FRES30 Desert shrub
- FRES32 Texas savanna
- FRES35 Pinyon-juniper
- FRES36 Mountain grasslands
- FRES37 Mountain meadows
- FRES38 Plains grasslands
- FRES39 Prairie
- FRES40 Desert grasslands
- FRES41 Wet grasslands
- FRES42 Annual grasslands
BLM Physiographic Regions (Bernard and Brown 1977)
- 1 Northern Pacific Border
- 2 Cascade Mountains
- 3 Southern Pacific Border
- 4 Sierra Mountains
- 5 Columbia Plateau
- 6 Upper Basin and Range
- 7 Lower Basin and Range
- 8 Northern Rocky Mountains
- 9 Middle Rocky Mountains
- 10 Wyoming Basin
- 11 Southern Rocky Mountains
- 12 Colorado Plateau
- 13 Rocky Mountain Piedmont
- 14 Great Plains
- 15 Black Hills Uplift
- 16 Upper Missouri Basin and Broken Lands
Kuchler Plant Associations (Kuchler 1964)
- K023 Juniper - pinyon woodland
- K038 Great Basin sagebrush
- K039 Blackbrush
- K048 California steppe
- K049 Tule marshes
- K050 Fescue - wheatgrass
- K055 Sagebrush steppe
- K056 Wheatgrass - needlegrass shrubsteppe
- K059 Trans-Pecos shrub savanna
- K063 Foothills prairie
- K064 Grama - needlegrass - wheatgrass
- K066 Wheatgrass - needlegrass
- K067 Wheatgrass - bluestem - needlegrass
- K068 Wheatgrass - grama - buffalograss
- K069 Bluestem - grama prairie
- K072 Sea oats prairie
- K073 Northern cordgrass prairie
- K074 Bluestem prairie
- K075 Nebraska Sandhills prairie
- K076 Blackland prairie
- K077 Bluestem - sacahuista prairie
- K078 Southern cordgrass prairie
- K079 Palmetto prairie
- K080 Marl - everglades
- K081 Oak savanna
- K084 Cross Timbers
- K086 Juniper - oak savanna
- K087 Mesquite - oak savanna
- K088 Fayette prairie
- K092 Everglades
- K105 Mangrove
- K114 Pocosin
SAF Cover Types (Eyre 1980)
- 16 Aspen
- 63 Cottonwood
- 74 Cabbage palmetto
- 105 Tropical hardwoods
- 106 Mangrove
- 217 Aspen
- 238 Western juniper
- 239 Pinyon - juniper
SRM Rangeland Cover Types (Shiflet 1994)
- No entry
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