Hen Harrier

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].

More info for the term: marsh

northern harrier
marsh hawk
blue hawk
white-rumped harrier
cinereous harrier
frog hawk

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].

More info for the term: herbaceous

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].

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].

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].

More info for the terms: backfire, cover, grassland, headfire, prescribed fire

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.

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This species is known to occur in association with the following cover types (as classified by the Society of American Foresters):

16 Aspen
63 Cottonwood
74 Cabbage palmetto
105 Tropical hardwoods
106 Mangrove
217 Aspen
238 Western juniper
239 Pinyon - juniper

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This species is known to occur in the following ecosystem types (as named by the U.S. Forest Service in their Forest and Range Ecosystem [FRES] Type classification):

More info for the term: shrub

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

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This species is known to occur in association with the following plant community types (as classified by Küchler 1964):

More info for the terms: shrub, woodland

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

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].

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

AB
BC
MB
NB
NF
NT
NS
ON
PE
PQ

SK
YT

MEXICO

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].

More info for the terms: forest, tussock

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].

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This species can be found in the following regions of the western United States (according to the Bureau of Land Management classification of Physiographic Regions of the western United States):

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

The currently accepted scientific name for northern harrier is Circus
cyaneus Linneaus [1]. There are three subspecies of northern harrier,
but only one of these, C. cyaneus ssp. hudsonius (Linnaeus), inhabits
North America [16].

More info for the term: polygamous

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]

More info for the term: fire regime

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].

FIRE REGIMES :
Find fire regime information for the plant communities in which this
species may occur by entering the species name in the FEIS home page under
"Find FIRE REGIMES".