Index of Species Information
WILDLIFE SPECIES: Buteo lagopus
Introductory
WILDLIFE SPECIES: Buteo lagopus
AUTHORSHIP AND CITATION :
Sullivan, Janet. 1995. Buteo lagopus. In: Fire Effects Information System, [Online].
U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station,
Fire Sciences Laboratory (Producer). Available:
www.fs.usda.gov/database/feis/animals/bird/bula/all.html [].
ABBREVIATION :
BULA
COMMON NAMES :
rough-legged hawk
American roughleg
TAXONOMY :
The accepted scientific name of the rough-legged hawk is Buteo lagopus
(Pontoppidan) [32]. The American subspecies is B. l. sanctijohannis
(Gmelin). Some authors include B. l. kamtschatkensis Dementiev
(Siberian roughleg) in occurrences of rough-legged hawks in northwestern
Alaska [1]; a different interpretation treats these as intermediate
between B. l. sanctijohannis and kamtschatkensis and places them with
sanctijohannis [28]. The type subspecies, B. l. lagopus (rough-legged
buzzard), is found only in Eurasia [1,28,37].
ORDER :
Falconiformes
CLASS :
Bird
FEDERAL LEGAL STATUS :
No special status
OTHER STATUS :
NO-ENTRY
WILDLIFE DISTRIBUTION AND OCCURRENCE
WILDLIFE SPECIES: Buteo lagopus
GENERAL DISTRIBUTION :
The breeding range of rough-legged hawk encompasses the high arctic
regions of the United States and Canada. The rough-legged hawk breeds
from western and northern Alaska, northern Yukon Territory, and northern
Labrador south to northern and southeastern MacKenzie District, central
Canada, and northern Quebec and Newfoundland. It also breeds from the
Kodiak islands and Umnak north to Prince Patrick, Victoria, Bylot, and
southwestern Baffin islands (Northwest Territories) [11,12,28,34].
The rough-legged hawk winters from south-central Alaska (casual) and
southern Canada south to southern California and southern Arizona, and
east to southern Texas, Missouri, Tennessee, and Virginia. On the East
Coast wintering rough-legged hawks occur from Cape Cod to Chesapeake Bay
and are occasionally observed in eastern Texas and on the Gulf Coast
[11,22,28].
ECOSYSTEMS :
FRES10 White-red-jack pine
FRES11 Spruce-fir
FRES15 Oak-hickory
FRES17 Elm-ash-cottonwood
FRES18 Maple-beech-birch
FRES19 Aspen-birch
FRES20 Douglas-fir
FRES21 Ponderosa pine
FRES22 Western white pine
FRES23 Fir-spruce
FRES24 Hemlock-Sitka spruce
FRES25 Larch
FRES26 Lodgepole pine
FRES27 Redwood
FRES28 Western hardwoods
FRES29 Sagebrush
FRES30 Desert shrub
FRES31 Shinnery
FRES32 Texas savanna
FRES33 Southwestern shrubsteppe
FRES34 Chaparral-mountain shrub
FRES35 Pinyon-juniper
FRES36 Mountain grasslands
FRES37 Mountain meadows
FRES38 Plains grasslands
FRES39 Prairie
FRES40 Desert grasslands
FRES41 Wet grasslands
FRES42 Annual grasslands
STATES :
| AK |
AZ |
AR |
CA |
CO |
CT |
DE |
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 |
|
|
|
|
|
|
|
|
BLM PHYSIOGRAPHIC REGIONS :
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 :
K002 Cedar-hemlock-Douglas-fir forest
K003 Silver fir-Douglas-fir forest
K004 Fir-hemlock forest
K005 Mixed conifer forest
K009 Pine-cypress forest
K010 Ponderosa shrub forest
K011 Western ponderosa forest
K012 Douglas-fir forest
K015 Western spruce-fir forest
K016 Eastern ponderosa forest
K017 Black Hills pine forest
K018 Pine-Douglas-fir forest
K019 Arizona pine forest
K020 Spruce-fir-Douglas-fir forest
K021 Southwestern spruce-fir forest
K022 Great Basin pine forest
K024 Juniper steppe woodland
K027 Mesquite bosque
K028 Mosaic of K002 and K026
K029 California mixed evergreen forest
K031 Oak-juniper woodlands
K032 Transition between K031 and K037
K033 Chaparral
K034 Montane chaparral
K037 Mountain-mahogany-oak scrub
K038 Great Basin sagebrush
K039 Blackbrush
K040 Saltbush-greasewood
K041 Creosotebush
K042 Creosotebush-bursage
K043 Paloverde-cactus shrub
K044 Creosotebush-tarbush
K045 Ceniza shrub
K055 Sagebrush steppe
K056 Wheatgrass-needlegrass shrubsteppe
K058 Grama-tobosa shrubsteppe
K059 Trans-Pecos shrub savanna
K060 Mesquite savanna
K061 Mesquite-acacia savanna
K062 Mesquite-live oak savanna
K071 Shinnery
K081 Oak savanna
K082 Mosaic of K074 and K100
K084 Cross Timbers
K086 Juniper-oak savanna
K087 Mesquite-oak savanna
K089 Black Belt
K093 Great Lakes spruce-fir forest
K094 Conifer bog
K095 Great Lakes pine forest
K096 Northeastern spruce-fir forest
K097 Southeastern spruce-fir forest
K098 Northern floodplain forest
K101 Elm-ash forest
K106 Northern hardwoods
K107 Northern hardwoods-fir forest
K108 Northern hardwoods-spruce forest
K109 Transition between K104 and K106
SAF COVER TYPES :
1 Jack pine
5 Balsam fir
21 Eastern white pine
22 White pine-hemlock
23 Eastern hemlock
24 Hemlock-yellow birch
35 Paper birch-red spruce-balsam fir
37 Northern white-cedar
51 White pine-chestnut oak
63 Cottonwood
95 Black willow
107 White spruce
201 White spruce
202 White spruce-paper birch
204 Black spruce
205 Mountain hemlock
206 Engelmann spruce-subalpine fir
207 Red fir
208 Whitebark pine
209 Bristlecone pine
212 Western larch
213 Grand fir
215 Western white pine
218 Lodgepole pine
219 Limber pine
220 Rocky Mountain juniper
223 Sitka spruce
224 Western hemlock
225 Western hemlock-Sitka spruce
226 Coastal true fir-hemlock
227 Western redcedar-western hemlock
228 Western redcedar
229 Pacific Douglas-fir
230 Douglas-fir-western hemlock
231 Port-Orford-cedar
234 Douglas-fir-tanoak-Pacific madrone
237 Interior ponderosa pine
238 Western juniper
243 Sierra Nevada mixed conifer
244 Pacific ponderosa pine-Douglas-fir
245 Pacific ponderosa pine
251 White spruce-aspen
253 Black spruce-white spruce
254 Black spruce-paper birch
256 California mixed subalpine
SRM (RANGELAND) COVER TYPES :
101 Bluebunch wheatgrass
102 Idaho fescue
103 Green fescue
104 Antelope bitterbrush-bluebunch wheatgrass
105 Antelope bitterbrush-Idaho fescue
106 Bluegrass scabland
107 Western juniper/big sagebrush/bluebunch wheatgrass
109 Ponderosa pine shrubland
110 Ponderosa pine-grassland
201 Blue oak woodland
203 Riparian woodland
206 Chamise chaparral
207 Scrub oak mixed chaparral
208 Ceanothus mixed chaparral
209 Montane shrubland
210 Bitterbrush
211 Creosotebush scrub
212 Blackbush
301 Bluebunch wheatgrass-blue grama
302 Bluebunch wheatgrass-Sandberg bluegrass
303 Bluebunch wheatgrass-western wheatgrass
304 Idaho fescue-bluebunch wheatgrass
305 Idaho fescue-Richardson needlegrass
306 Idaho fescue-slender wheatgrass
307 Idaho fescue-threadleaf sedge
309 Idaho fescue-western wheatgrass
310 Needle-and-thread-blue grama
311 Rough fescue-bluebunch wheatgrass
312 Rough fescue-Idaho fescue
314 Big sagebrush-bluebunch wheatgrass
315 Big sagebrush-Idaho fescue
316 Big sagebrush-rough fescue
317 Bitterbrush-bluebunch wheatgrass
318 Bitterbrush-Idaho fescue
319 Bitterbrush-rough fescue
320 Black sagebrush-bluebunch wheatgrass
321 Black sagebrush-Idaho fescue
322 Curlleaf mountain-mahogany-bluebunch wheatgrass
323 Shrubby cinquefoil-rough fescue
324 Threetip sagebrush-Idaho fescue
401 Basin big sagebrush
402 Mountain big sagebrush
403 Wyoming big sagebrush
404 Threetip sagebrush
405 Black sagebrush
406 Low sagebrush
407 Stiff sagebrush
408 Other sagebrush types
409 Tall forb
411 Aspen woodland
412 Juniper-pinyon woodland
413 Gambel oak
414 Salt desert shrub
415 Curlleaf mountain-mahogany
416 True mountain-mahogany
417 Littleleaf mountain-mahogany
418 Bigtooth maple
419 Bittercherry
420 Snowbrush
421 Chokecherry-serviceberry-rose
422 Riparian
501 Saltbush-greasewood
502 Grama-galleta
503 Arizona chaparral
504 Juniper-pinyon pine woodland
505 Grama-tobosa shrub
506 Creosotebush-bursage
507 Palo verde-cactus
508 Creosotebush-tarbush
509 Transition between oak-juniper woodland and mahogany-oak association
601 Bluestem prairie
602 Bluestem-prairie sandreed
603 Prairie sandreed-needlegrass
604 Bluestem-grama prairie
605 Sandsage prairie
606 Wheatgrass-bluestem-needlegrass
607 Wheatgrass-needlegrass
608 Wheatgrass-grama-needlegrass
609 Wheatgrass-grama
610 Wheatgrass
611 Blue grama-buffalograss
612 Sagebrush-grass
614 Crested wheatgrass
615 Wheatgrass-saltgrass-grama
701 Alkali sacaton-tobosagrass
702 Black grama-alkali sacaton
703 Black grama-sideoats grama
704 Blue grama-western wheatgrass
705 Blue grama-galleta
706 Blue grama-sideoats grama
707 Blue grama-sideoats grama-black grama
708 Bluestem-dropseed
709 Bluestem-grama
710 Bluestem prairie
712 Galleta-alkali sacaton
713 Grama-muhly-threeawn
714 Grama-bluestem
715 Grama-buffalograss
716 Grama-feathergrass
717 Little bluestem-Indiangrass-Texas wintergrass
718 Mesquite-grama
719 Mesquite-liveoak-seacoast bluestem
720 Sand bluestem-little bluestem (dunes)
721 Sand bluestem-little bluestem (plains)
722 Sand sagebrush-mixed prairie
724 Sideoats grama-New Mexico feathergrass-winterfat
725 Vine mesquite-alkali sacaton
727 Mesquite-buffalograss
728 Mesquite-granjeno-acacia
729 Mesquite
730 Sand shinnery oak
731 Cross timbers-Oklahoma
732 Cross timbers-Texas (little bluestem-post oak)
733 Juniper-oak
734 Mesquite-oak
801 Savanna
802 Missouri prairie
803 Missouri glades
804 Tall fescue
805 Riparian
806 Gulf Coast salt marsh
807 Gulf Coast fresh marsh
809 Mixed hardwood and pine
819 Freshwater marsh and ponds
822 Slough
PLANT COMMUNITIES :
Breeding Habitat: The breeding habitat of rough-legged hawk is open
tundra and mountains; the southern limit of its breeding range coincides
with the latitudinal tree line [11,22]. Rough-legged hawks occasionally
nest in trees at the edge of boreal forest [22]. The rough-legged hawk
is not usually observed in forests, except where there is much open
ground. Kochert [24] listed tundra and taiga as breeding habitat for
the rough-legged hawk.
Wintering Habitat: The rough-legged hawk prefers conifer groves for
roosting and hunts in open, treeless areas [11]. Kochert [24] listed
rough-legged hawk wintering habitat as open shrub and grassland in
temperate areas. Rough-legged-hawks were observed wintering in pinyon
(Pinus spp.)-juniper (Juniperus spp.) woodlands in the southwestern
United States [4].
REFERENCES :
NO-ENTRY
BIOLOGICAL DATA AND HABITAT REQUIREMENTS
WILDLIFE SPECIES: Buteo lagopus
TIMING OF MAJOR LIFE HISTORY EVENTS :
Breeding: Age at first breeding is 2 to 3 years [22]. Rough-legged
form pair bonds that are maintained for at least the duration of the
breeding season and possibly longer. There is some evidence that pair
bonding occurs in wintering areas; birds roost and perch in twos and
sometimes migrate in twos [28]. After the loss of a mate, a new mate is
usually acquired fairly rapidly [22]. There is usually only one brood
per season [12].
Spring Migration: Rough-legged hawks travel in loose flocks; up to 10
birds may be seen at a time, though hundreds might pass a hawk station
in a day. Rough-legged hawks are not averse to crossing wide bodies of
water, which is unusual for a buteo. They migrate across boreal forest
to find open country [28]. In the western part of rough-legged hawk
range, spring migration begins in late March or early April, with the
largest flights in late April. Breeding pairs arrive on the breeding
grounds in late April to early May [37]. In the eastern part of its
range, rough-legged hawk migration occurs from early March to late April
or the first week of May; the peak period is in late March [20].
Nest: The nest is constructed of sticks, bones, other debris, weeds,
and grass, and is lined with grass, down, feathers, and the fur of prey
animals [12]. Nests tend to be larger in areas where more sticks are
available. Typical nests range in size from 24 to 30 inches (61-76 cm)
across and 20 to 22 inches (50-55 cm) deep [37]. Nests are used
repeatedly and become larger as new material is added [22].
Clutch: Eggs have been observed in rough-legged hawk nests from May to
June, sometimes as late as July [34]. Earliest egg dates were May 2 in
Labrador and May 18 in arctic Canada and Alaska. Latest egg dates were
June 23 in Labrador and July 13 in arctic Canada and Alaska [28]. In
captivity eggs are laid at 2-day intervals; on average, clutches of five
eggs take 10 days to lay [22]. Clutch size is variable and ranges from
two to seven eggs; clutches are smaller when prey is scarce [12].
Clutches of five to seven eggs are common in good lemming (Lemmus and
Dicrostonyx spp.) years; clutches of two or three eggs are more common
in poor lemming years [22].
Incubation: Eggs are incubated for 28 to 31 days, mostly by the female.
The male feeds her, guards the nest, and incubates the eggs for only
short periods [28,37]. Eggs hatch asynchronously [12].
Development of Young: Rough-legged hawk chicks are semialtricial; at
hatching they are immobile and downy with eyes open. They are fed by
both parents. Age of first flight is usually between 36 and 40 days
[12]. Most rough-legged hawk young leave the nest in early July to
mid-August at approximately 6 weeks of age but continue to depend on the
parents for food for a short period thereafter [37]. Dependence on the
parents for food sometimes extends to fall migration [28].
Fall Migration: There is usually no large and distinct peak for
autumnal rough-legged hawk flights as there is in the spring [20]. At a
hawk-watching station on the shore of Lake Superior, peak flights of
migrating rough-legged hawks occurred from October 13 through the 31st.
The rough-legged hawk arrives in wintering areas in September and
October, and is settled from November through March [22].
Longevity: The average life span of the rough-legged hawk is 20.7
months [28]. Rough-legged hawks have been reported as old as 6 years 9
months [34] and 18 years 1 month [28].
Population Fluctuations: There are wide fluctuations in local winter
populations of rough-legged hawk in the southwestern United States [4].
Localized nonseasonal migrations of rough-legged hawk occur when prey
populations crash in usual breeding areas and the hawks move to areas of
more abundant prey [12].
Diurnal Patterns in Winter: Most rough-legged hawks are active during
sunlight hours and retire to night perches by 4:30 p.m. [28]. Peak
activity is usually observed during periods of high wind velocity, clear
sky, rising air pressure, low relative humidity and high temperature [37].
Diurnal Patterns in Summer: In Finland, rough-legged buzzards were
observed active by 4 a.m. in June and July. They remained active
throughout the day until 8 p.m. (sometimes as late as 10 p.m.) [29].
Rough-legged hawks have occasionally been observed hunting between 12 a.m.
and 3 a.m. in arctic Alaska [37].
PREFERRED HABITAT :
Nesting: Rough-legged hawk nests are usually built on cliffs, river
bluffs, rocky outcroppings and ledges, columnar rocks, artificial
structures such as cairns, on the ground on steep hillsides, and rarely,
in trees [11,22,28]. Sites with an overhanging ledge or caprock are
preferred [22]. There appears to be a tendency to nest in clusters of
breeding pairs; however, this may be a function of nest site
availability [28]. Estimated average breeding density is approximately
one pair per 3.1 square miles (7.8 sq km). Highest recorded density was
one pair per 1.6 square miles (4 sq km); however, there is often only
one pair per 31.2 square miles (78 sq km) [8]. Near the Colville River,
Alaska, nests averaged 2.3 linear miles (3.8 km) apart, ranging from
0.24 to 13.2 miles (0.4-22 km) apart. Rough-legged hawks usually return
to the same nest site from year to year, even in the face of heavy
competition from peregrine falcons (Falco peregrinus) or gyrfalcons (F.
rusticolus) for the same site [22]. Rough-legged hawks are not as
aggressive as the late-migrating peregrine falcons, which often displace
rough-legged hawks from nest sites [22,28].
Hunting: The rough-legged hawk prefers to hunt in open areas: wet
meadows, bogs, marshes, riparian areas, pastures, and shrub-grass
uplands [4,24]. Hunting territory size during the breeding season is
variable; it may be as small as 2 to 2.4 square miles (5-6 sq km) when
prey density is high [22].
Wintering: Rough-legged hawks usually winter in open country:
farmlands [32], plains, prairies, airports and other open urban areas,
coastal marshes, and agricultural lands. The winter home range usually
ranges from 4 to 6 square miles (10-15 sq km) [22]. Competition where
winter ranges overlap those of the red-tailed hawk (Buteo jamaicensis)
is mitigated by behavioral differences in hunting styles; for example,
rough-legged hawks hunt from lower perches, prefer more open areas, and
avoid snow cover more than red-tailed hawks do [37]. The rough-legged
hawk is absent from northern regions where the average minimum January
temperature is less than -10 degrees Fahrenheit (-23 deg C). This hawk
tends to avoid the western coastline and the southeastern corner of the
United States. It is most abundant in areas with less than 40 inches
(1,020 mm) annual precipitation [28].
COVER REQUIREMENTS :
Nest sites appear to be selected at least partly for a wide view [22,29]
FOOD HABITS :
During the breeding season, the rough-legged hawk preys primarily on
microtine rodents (Microtus and Peromyscus spp.), brown lemming (Lemmus
sibericus), Nelson's collared lemming (Dicrostonyx groenlandicus),
tundra vole (M. oeconomus), singing vole (M. miurus), northern
red-backed vole (Cleithrionomys rutilis), and other small mammals [4].
Lemmings may comprise 80 to 85 percent of the summer diet [28]. In the
Northwest Territories brown lemmings comprised 83 percent of
rough-legged hawk summer diet, with lesser amounts of collared lemming
and arctic ground squirrel (Spermophilus parryi) [37], and
occassionally, Alaska hare (Lepus othus) [28]. Other food items include
insects and carrion [12]. Rough-legged hawks have been observed
consuming ringed seal (Phoca hispida) and caribou (Rangifer tarandus)
carcasses [39]. Springer reported that up to 30 percent of breeding
season diet in Alaska was avian prey, and consisted mostly of fledgling
passerines, ptarmigan (Lagopus spp.), and occasionally lesser
golden-plover (Pluvialis dominica) [33]. Palmer and Mindell [28]
reported that avian prey of rough-legged hawks in Alaska included grouse
(probably spruce grouse [Dendrapagus canadensis]) chicks, shorebirds,
lesser golden-plover, red-necked phalarope (Phalaropus lobatus),
whimbrel (Numenius phaeopus) chicks and juveniles, and other small birds
such as wagtail (Motacilla spp.), American tree sparrow (Spizella
arborea), Lapland longspur (Calcarius lapponicus), and snow bunting
(Plectrophenax nivalis) [28].
Winter diet is almost exclusively small mammals [4]. Palmer and Mindell
[28] estimated that voles comprise up to 80 or 90 percent of the winter
diet of rough-legged hawks, but occasionally birds as large as
ring-necked pheasant (Phasianus colchicus) and gray partridge (Perdix
perdix) may be taken [22]. On occasion weasels (Mustela spp.), ground
squirrels (Spermophilus spp.), rats (Rattus spp.), house mouse (Mus
musculus), and shrews (Crystotis, Sorex, and Blarina spp.) are eaten
[28]. In Iowa, wintering rough-legged hawks consumed meadow vole
(Microtus pennsylvanicus), western harvest mouse (Reithrodontomys
megalotis), and occasionally eastern cottontail (Silvilagus floridanus).
At another site in Iowa, deer mouse (Peromyscus maniculatus) and house
mouse were important in winter diets [37]. Wintering rough-legged hawks
have been observed fishing, and are also known to take frogs [28,37]. A
rough-legged hawk was observed stealing prey from a northern harrier
(Circus cyaneus), and rough-legged hawks were observed with other
raptors as prey, including sharp-shinned hawk [Accipiter striatus]) [28]
and short-eared owl (Asio flammeus) [27].
Hunting Style: Much hunting is done from perches, including relatively
low sites such as fenceposts, poles, and even slightly elevated sites
such as rocks or mounds [22]. The rough-legged hawk frequently hovers
over one spot at an altitude of 50 to 132 feet (15-40 m) [28]. There is
also an appreciable amount of low-altitude flap and glide hunting for
mice; a rough-legged hawk often will quarter back and forth over open
fields [28,34].
PREDATORS :
Rough-legged hawks have few natural enemies. Terrestrial predators
include arctic fox (Alopex lagopus) and red fox (Vulpes vulpes), but
nests are usually so inaccessible and so well guarded as to preclude
much nest predation by foxes. Gray wolves (Canis lupus) and golden eagles
(Aquila chrysaetos) have been observed eating young rough-legged hawks
in nests in Alaska [37].
MANAGEMENT CONSIDERATIONS :
The rough-legged hawk is one of North America's most abundant raptors
[12]. Although no historical data on rough-legged hawk populations are
available, it is probable that the rough-legged hawk is currently stable
in North America [36]. White and Cade [38] assert that rough-legged
hawks are probably stable as a breeding population in Alaska, except
where oil and gas drilling sites, roads, pipeline development, and other
installations destroy nest habitat. The estimated North American winter
population of rough-legged hawks was 49,600 based on 1986 Christmas bird
count data [12]. The maximum winter densities of rough-legged hawk
occurred in Montana and Idaho, with estimated state populations of 5,250
and 3,650 birds, respectively [22]. Several studies on the abundance of
rough-legged hawks are available [3,6,15]. Conservation and management
of the rough-legged hawk depends on factors affecting habitat in Canada
and the United States [7].
Population sizes and local abundance of rough-legged hawk are strongly
influenced by local prey populations [22]. Local rough-legged hawk
populations have been observed to increase and decrease with rodent prey
availability; local population size is apparently a function of hawk
movement to areas with abundant prey (rather than an absolute increase
or decrease). For example, on the Seward Peninsula, there were 35
nesting pairs of rough-legged hawks in 1968, 43 pairs in 1969, and 82
pairs in 1970; however, only 10 pairs were found and two young fledged
in 1971 following a severe autumn in 1970 which held microtine
populations low. In 1972, there were 44 nesting pairs [37]. In Norway
high density of breeding pairs of rough-legged buzzards corresponded
with high density of voles [19]. Palmer and Mindell [28], however,
asserted that fluctuations in vole populations probably influence but
are not the sole cause of rough-legged hawk population fluctuations
since rough-legged hawks shift to other prey when voles are scarce. The
degree to which rough-legged hawk breeding success is independent of
vole population is related to the availability and use of alternate prey
[28]. Microtine rodent population fluctuations appear to be random
rather than cycling at 4-year or 10-year intervals, as has been
previously asserted, which further complicates understanding of the
relationship of rough-legged hawk populations to prey populations [18].
In Finland rough-legged buzzard nesting density was reported to be
independent of small mammal stocks; good nesting success occurred even
in poor vole years [29]. Winter rough-legged hawk populations are often
concentrated in areas of high prey density [37].
At a hawk migration station on Lake Superior, rough-legged hawks were
the most numerous raptor observed in 1979, even though 1979 was probably
a low population year for rough-legged hawks [13]. Migration counts of
rough-legged hawks at Bake Oven Knob, Pennsylvania, were variable,
increasing and decreasing in what appeared to be 3- to 5-year cycles.
Cycles were also reported for migration counts at Hawk Mountain, Maine
[21]. In New Jersey wintering population densities of rough-legged
hawks varied widely between years but showed no obvious upward or
downward trend [7].
Rough-legged hawks banded in California bred in several locations, from
Alaska to Banks Island in the Northwest Territories. Encounters with
banded rough-legged hawks suggest that rough-legged hawks from the
western part of the breeding range migrate to the western parts of the
winter range. Rough-legged hawks also show strong fidelity to the same
winter area in subsequent years; this suggests that the loss of
wintering habitat to residential development could be detrimental to
rough-legged hawk populations [16]. Wintering concentrations of
rough-legged hawks in the Great Plains and the Intermountain West were
correlated primarily with climate and the presence of protected areas
such as wildlife refuges.
The rough-legged hawk is most common in the Great Basin and the Northern
Great Plains. Winter populations are high in Montana, northern Oregon,
southern Washington, and northeastern Maine north to Newfoundland [30].
A drive-by survey in southeastern Idaho revealed that rough-legged hawks
were the most abundant raptor, appearing most often on agricultural land
[10]. Wintering rough-legged hawks are widely distributed throughout
New Jersey, but appear to prefer coastal areas. Abundance in New Jersey
was significantly correlated (p < 0.002) with wetlands; rough-legged
hawks also appear to avoid areas with snow cover [7].
Mortality Factors: The rough-legged hawk is often relatively
unsuspicious of human approach. Prior to their legal protection,
rough-legged hawks were shot in large numbers in wintering areas of the
United States or were caught in pole traps. In Utah large numbers of
migrant rough-legged hawks were reported killed by cars while feeding on
road-killed jackrabbits (Lepus spp.) [35,37]. In 1967 mortality from
dieldrin poisoning was documented in rough-legged buzzards in Britain.
Consumption of only a few animals that had eaten dieldrin-treated grain
was sufficient to kill the hawks [37].
REFERENCES :
NO-ENTRY
FIRE EFFECTS AND USE
WILDLIFE SPECIES: Buteo lagopus
DIRECT FIRE EFFECTS ON ANIMALS :
There are no reported mortalities of rough-legged hawks from fire in the
literature. It is likely that fire mortality of raptors is confined to
nestlings [26]; the placement of most rough-legged hawk nests makes this
very unlikely.
HABITAT RELATED FIRE EFFECTS :
There has only been one review of the relationship between raptor
habitat and fire and no specific information was available for
rough-legged hawk [36].
Fire Effects on Prey Species: Fire usually causes temporary declines in
populations. Vegetation recovery after fire usually increases available
vegetative biomass. Small mammal population declines are compensated
for in 1 or 2 years [23]. In a study of the effects of vegetation
manipulation on small mammal populations, Cornely and others [9]
compared burned plots to untreated plots and plots that had been mowed.
Montane vole (Microtus montanus) populations were low immediately
following a November 1978 prescribed fire, but were higher than any
other treatments on burned plots in January 1980. Immediately after
burning, rodent populations were lower on burned plots than on untreated
plots [9].
Open habitats that are frequented by rough-legged hawks and dependent on
fire include grassland, semidesert grass-shrub, and sagebrush (Artemisia
spp.)-grassland. Grasslands are maintained by frequent fire (1- to
10-year average fire return intervals). Fire exclusion in the deciduous
forest-prairie ecotone has reduced available rough-legged hawk winter
habitat. Increased shrub densities have occurred in the last 80 years
in semidesert grass-shrub habitats. These habitats typically have
average fire-free intervals of 10 years; the causal mechanism for the
increase in shrub density is not well understood; primary causes are
probably increased grazing, and increased fire intensity and frequency due
to fire exclusion and cheatgrass (Bromus tectorum) invasion.
Sagebrush-grass habitats, with fire-free intervals ranging from 20 to
100 years, have also been altered by cheatgrass invasion which probably
has increased fire frequency [26].
FIRE USE :
NO-ENTRY
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".
REFERENCES :
NO-ENTRY
References for species: Buteo lagopus
1. American Ornithologists' Union. 1957. Checklist of North American birds. 5th ed. Baltimore, MD: The Lord Baltimore Press, Inc. 691 p. [21235]
2. American Ornithologists' Union. 1983. Checklist of North American birds. 6th ed. Lawrence, KS: Allen Press, Inc. 877 p. [21234]
3. Andersen, D. E.; Rongstad, O. J.; Mytton, W. R. 1985. Line transect analysis of raptor abundance along roads. Wildlife Society Bulletin. 13(4): 533-539. [24591]
4. Balda, Russell P.; Masters, Nancy. 1980. Avian communities in the pinyon-juniper woodland: a descriptive analysis. In: DeGraaf, Richard M., technical coordinator. Management of western forests and grasslands for nongame birds: Workshop proceedings; 1980 February 11-14; Salt Lake City, UT. Gen. Tech. Rep. INT-86. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Forest and Range Experiment Station: 146-169. [17903]
5. Bernard, Stephen R.; Brown, Kenneth F. 1977. Distribution of mammals, reptiles, and amphibians by BLM physiographic regions and A.W. Kuchler's associations for the eleven western states. Tech. Note 301. Denver, CO: U.S. Department of the Interior, Bureau of Land Management. 169 p. [434]
6. Bildstein, Keith Louis. 1978. Behavioral ecology of red-tailed hawks (Buteo jamaicensis), rough-legged hawks (B. lagopus), and northern harriers (Circus cyaneus). Columbus, OH: Ohio State University. 364 p. Dissertation. [24993]
7. Bosakowski, Thomas; Smith, Dwight G. 1992. Demography of wintering rough-legged hawks in New Jersey. Journal of Raptor Research. 26(2): 61-65. [24445]
8. Brown, Leslie; Amadon, Dean. 1968. Eagles, hawks and falcons of the world. Vol. 2. New York: McGraw-Hill Book Company. 945 p. [22970]
9. Cornely, J. E.; Britton, C. M.; Sneva, F. A. 1983. Manipulation of flood meadow vegetation and observations on small mammal populations. Prairie Naturalist. 15: 16-22. [14509]
10. Craig, Timothy H. 1978. A car survey of raptors in southeastern Idaho 1974-1976. Raptor Research. 12(1/2): 40-45. [24444]
11. DeGraaf, Richard M.; Scott, Virgil E.; Hamre, R. H.; [and others]. 1991. Forest and rangeland birds of the United States: Natural history and habitat use. Agric. Handb. 688. Washington, DC: U.S. Department of Agriculture, Forest Service. 625 p. [15856]
12. Ehrlich, Paul R.; Dobkin, David S.; Wheye, Darryl. 1988. The birder's handbook: a field guide to the natural history of North American birds. New York: Simon & Schuster, Inc. 785 p. [21559]
13. Escott, Nicholas G. 1985. Fall migration of the rough-legged hawk at Marathon, Ontario. In: Harwood, Michael, ed. Proceedings of the hawk migration conference: IV; [Date of conference unknown]; [Location of conference unknown]. [Place of publication unknown]: Hawk Migration Association: 27-39. On file with: U.S. Department of Agriculture, Forest Service, Intermountain Research Station, Fire Sciences Laboratory, Missoula, MT. [24584]
14. Eyre, F. H., ed. 1980. Forest cover types of the United States and Canada. Washington, DC: Society of American Foresters. 148 p. [905]
15. Li, X. J.; Burton, P. J.; Leadem, C. L. 1994. Interactive effects of light and stratification on the germination of some British Columbia conifers. Canadian Journal of Botany. 72: 1635-1646. [24594]
16. Garrison, Barrett A.; Bloom, Peter H. 1993. Natal origins and winter site fidelity of rough-legged hawks wintering in California. Journal of Raptor Research. 27(2): 116-118. [24961]
17. Garrison, George A.; Bjugstad, Ardell J.; Duncan, Don A.; [and others]. 1977. Vegetation and environmental features of forest and range ecosystems. Agric. Handb. 475. Washington, DC: U.S. Department of Agriculture, Forest Service. 68 p. [998]
18. Garsd, Armando; Howard, Walter E. 1981. A 19-year study of microtine population fluctuations using time-series analysis. Ecology. 62(4): 930-937. [24593]
19. Hagen, Yngvar. 1969. Norwegian studies on the reproduction of birds of prey and owls in relation to micro-rodent population fluctuations. Fauna. 22: 73-126. [24960]
20. Heintzelman, Donald S. 1979. Guide to hawk watching in North America. University Park, PA: The Pennsylvania State University Press. 284 p. [24546]
21. Heintzelman, Donald S. 1986. The migration of hawks. Bloomington, IN: Indiana University Press. 369 p. [24447]
22. Johnsgard, Paul A. 1990. Hawks, eagles, and falcons. Washington, DC: Smithsonian Institution Press. 403 p. [21510]
23. Kayll, A. J. 1968. The role of fire in the boreal forest of Canada. Information Report PS-X-7. Chalk River, ON: Department of Forestry and Rural Development of Canada, Petawawa Forest Experiment Station. 15 p. [24962]
24. Kochert, Michael N. 1986. Raptors. In: Cooperrider, Allan Y.; Boyd, Raymond J.; Stuart, Hanson R., eds. Inventory and monitoring of wildlife habitat. Denver, CO: U.S. Department of the Interior, Bureau of Land Management, Denver Service Center: 313-349. [13527]
25. Kuchler, A. W. 1964. Manual to accompany the map of potential vegetation of the conterminous United States. Special Publication No. 36. New York: American Geographical Society. 77 p. [1384]
26. Lehman, Robert N.; Allendorf, John W. 1989. The effects of fire, fire exclusion and fire management on raptor habitats in the western United States. In: Proceedings of the western raptor management symposium and workshop; 1987 October 26-28; Boise, ID. Scientific and Technical Series No. 12. Washington, DC: National Wildlife Federation: 236-244. [22324]
27. Maxson, Stephen J.; Herr, Andrea M. 1990. Rough-legged hawk preys on short-eared owl. Loon. 62(2): 108. [22378]
28. Palmer, Ralph S., ed. 1988. Handbook of North American birds. New Haven, CT: Yale University Press. 5 volumes. [23780]
29. Pasanen, Seppo; Sulkava, Seppo. 1971. On the nutritional biology of the rough-legged buzzard, Buteo lagopus lagopus Brunn., in Finnish Lapland. Aquilo Seria Zoologica. 12: 53-63. [28326]
30. Root, Terry. 1988. Atlas of wintering North American birds. Chicago: University of Chicago Press. 312 p. [24443]
31. Shiflet, Thomas N., ed. 1994. Rangeland cover types of the United States. Denver, CO: Society for Range Management. 152 p. [23362]
32. Sibley, Charles G.; Monroe, Burt L., Jr. 1990. Distribution and taxonomy of the birds of the world. New Haven, CT: Yale University Press. 1111 p. [22814]
33. Springer, Alan M. 1975. Observations on the summer diet of rough-legged hawks from Alaska. The Condor. 77: 338-339. [24592]
34. Terres, John K. 1980. The Audubon Society encyclopedia of North American birds. New York: Alfred A. Knopf. 1109 p. [16195]
35. White, Clayton M. 1969. Population trends in Utah raptors. In: Hickey, Joseph J., ed. Peregrine falcon populations: the biology and decline. Madison, WI: University of Wisconsin Press: 596. [24446]
36. White, Clayton M. 1994. Population trends and current status of selected western raptors. Studies in Avian Biology. 15: 161-172. [24512]
37. Zarn, Mark. 1975. Rough-legged hawk (Buteo lagopus sanctijohannis): Habitat management series for unique or endangered species: Report No. 14. Technical Note T-N-270. Denver, CO: U.S. Department of the Interior, Bureau of Land Management. 23 p. [24516]
38. White, Clayton M.; Cade, Tom J. 1971. Cliff-nesting raptors and ravens along the Colville River in arctic Alaska. Living Bird. 10: 107-150. [24513]
39. Smith, Thomas G. 1975. Rough-legged hawks, Buteo lagopus (Pontoppidan) as carrion feeders in the Arctic. Canadian Field-Naturalist. 89: 190. [24515]
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