Search USGS⌕ Search

SEARCH · Search USGS

Results for “Journal of Raptor Research”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 127 records · Page 7Linked to original sources
USGS1994

Should we terminate an 'artificial,' tree-nesting raptor population in Arizona?

The Altar Valley in southcentral Arizona was once a iallgrass prairie. Overgrazing prevented fire and spread mesquite, allowing the area, now a savanna, to be heavily used by tree-nesting raptors in summer and heavily hunted by perch-hunting raptors in winter. The breeding raptor community (over 150 pairs) consists primarily of red-tailed hawks (Buteo jamaicensis), great horned owls (Bubo virginianus), and Swainson's hawks (Buteo swainsoni). Common ravens (Corvus corax) are also common and there is a recently discovered small population of black-shouldered kites (Elanus caeruleus). Recent efforts to restore the endangered masked bobwhite (Colinus virginianus) to the area clash with habitat needs of the raptors. This conflict focuses attention on the 'multiple use' concept and calls for implementation of a 'prime use' or 'highest and best use' management strategy. Prime use (this is the only area in the United States managed for the masked bobwhite) 'will likely call for the removal of trees over much of the Altar Valley. This removal will likely result in the nearly total loss of nesting and perching sites for breeding, migrating, and wintering raptors.

Journal of Raptor Research↗
USGS1994

Harpy eagle (Harpia harpyja) nesting in manipulated forests

Continental records point to shooting, removal of young and destruction of nests as the primary conservation problems for harpy eagles (Harpia harpyja); bird-observer visits are a new source of concern. Nesting events are roughly 3 yr apart. Nests are used during and after intensive manipulation of the surrounding habitat, and minimum distance between active sites was 3-5 km. In nine nesting sites along a 100-km stretch of the Imalaca Mountains in Venezuela, we fitted five fledglings with satellite-tracked tags from NASA. One of these birds was hacked with the help of the loggers who destroyed its nest. All these nests were active while logging ensued. Out of three renesting attempts, one failed when the nest collapsed. We salvaged two additional fledglings found in captivity. We are monitoring five nests in the buffer area of the Darien National Park in Panama, all within 3 km of human settlements where trees are regularly felled for firewood, lumber, and to clear more cropland. Eagles have been killed at two sites, a third site remains inactive since 1991, and the other two nests currently have fledglings.

Journal of Raptor Research↗
USGS1994

Diurnal raptors in the fragmented rain forest of the Sierra Imataca, Venezuela

The rain forest of the Sierra Imataca in eastern Venezuela has been subjected to extensive deforestation for pastures and agricultural settlements. In the last decade the opening of access roads combined with intensified logging and mining activities have fragmented a significant portion of the remaining forest. We noted local distribution and habitat use for 40 species of diurnal raptors observed in ten affected areas, including raptors considered as forest interior species and some open country species utilizing the man-made openings inside the forest for roosting and foraging.

Journal of Raptor Research↗
USGS1993

Recent distribution and status of nesting bald eagles in Baja California, Mexico

We studied Bald Eagles(Haliaeetus leucocephalus) nesting in Baja California, Mexico, and vicinity from 1983-1993. The range of nesting Bald Eagles in Baja California has been reduced from a scattering of pairs along both the Pacific and Gulf sides to a remnant population in Magdalena Bay where no more than three pairs were found annually. Low numbers and a restricted distribution make this disjunct population especially vulnerable to human disturbance. Additional protection of present nesting localities and a reintroduction program on remote islands in the Gulf of California where eagles historically nested, are proposed. Limited data on nesting success indicate that the Magdalena Bay population is reproducing successfully with young probably dispersing north following fledging. The Bald Eagles found wintering along the Colorado River Delta in January apparently nest farther north in the United States or Canada.

Journal of Raptor Research↗
USGS1991

Environmental contaminants in bald eagle eggs

Bald Eagle eggs (1968-84) were analyzed for organochlorine pesticides, PCBs and mercury. DDE declined in WI, ME and the Chesapeake Bay. DDE was most closely related to shell thickness and reproduction at sampled breeding areas. Sixteen ppm DDE (wet weight) was associated with 15% shell thinning. Reproduction was normal when eggs at sampled breeding areas contained <3.6 ppm DDE; success was nearly halved between 3.6 and 6.3 ppm and halved again when concentrations exceeded 6.3 ppm. Other contaminants were associated with poor reproduction and eggshell thinning; however, their impact appeared secondary to that of DDE.

Journal of Raptor Research↗
USGS1993

Cryopreservation of American kestrel semen with dimethylsulfoxide

Semen samples from 15 male American Kestrels (Falco sparverius) were frozen in dimethyl sulfoxide (DMSO). The semen was thawed 1-14 mo later and used to inseminate six females during three breeding seasons. Kestrels inseminated with thawed semen containing 4% DMSO produced only infertile eggs (N = 14). Kestrels inseminated with thawed semen containing 6%, 8%, or 10% DMSO produced fertile eggs (N = 14) and live chicks (N = 6). Progressive motility of spermatozoa in thawed semen containing 10% DMSO was less (44 ? 6%) than in thawed semen containing 6% (62 ? 10%) or 8% (61 ? 1%) DMSO.

Journal of Raptor Research↗
USGS1992

Organochlorines and mercury in osprey eggs from the eastern United States

Organochlorine and mercury concentrations were determined in Osprey eggs collected from Maryland, Virginia, and Massachusetts during 1986-87. DDE concentrations were significantly different among locations. Median DDE concentrations did not decline significantly in eggs from Glenn L. Martin National Wildlife Refuge, Maryland, between 1973 and 1986. The median DDE residue for eggs from Martin Refuge in 1986 surpassed the value associated with 10% eggshell thinning, but was below the value associated with production of 1.0 young per active nest, a level assumed to represent a stable population. DDD, DDT, dieldrin, PCB, and mercury residues in all eggs appeared insignificant with regard to potential effects on shell thickness or reproduction. DDE and PCB residues were lower in eggs collected in 1986-87 than in those collected in the 1970s for each area. DDD, DDT, and dieldrin were not detected in Martin Refuge eggs in 1986, representing a significant reduction since 1973. DDD, DDT, and dieldrin levels in Massachusetts and Virginia eggs in 1986-87 were similar to those in eggs from the 1970s for each state. Mercury residues in eggs from Martin Refuge may be increasing and although not significant in this study, may warrant future monitoring.

Journal of Raptor Research↗
USGS1992

Determining sex of eastern screech-owls using discriminant function analysis

Seven morphometric characteristics and weight of males and females of a captive colony of Eastern Screech-Owls (Otus asio) were compared. Females were significantly larger than males in weight, total length, and length of tail, wing and bill. A discriminant function analysis based on weight, wing and tail length correctly identified the sex of 88% of the 77 birds.

Journal of Raptor Research↗
USGS1992

Distribution and color variation of gyrfalcons in Russia

Gyrfalcon (Falco rusticolus) museum specimens in Moscow (73) and St. Petersburg (132) were divided into four color classes (gray, light gray, white gray, and white) and four longitudinal belts representing major physiographic regions of northern Russia. Gray variants predominated in the west and central regions. White birds were most common in extreme eastern Siberia, but were occasionally found even west of the Ural Mountains. Frequencies were as follows: European Russia 4% white, 50% gray (the remainder were intermediates); western Siberia 0% white, 58% gray; central Siberia 15% white, 42% gray; and eastern Siberia 47% white, 33% gray. Remarkably, in the easternmost subregion, white birds predominated even near the southernmost extension. Because the northernmost portions of the species' range in continental Russia are in central Siberia where white variants were rare, we propose that a better predictor of the white variant is longitude, not latitude. White birds were most frequent at the eastern reaches of both the Palearctic and Nearctic. The best environmental correlates of this distribution pattern may be the southward bending thermal isoclines proceeding eastward toward Greenland or Kamchatka, where both land masses are bathed by cold oceanic currents of Arctic origin. By contrast, the western reaches of both land masses are bathed by warm currents. In these western reaches, Gyrfalcon summer distribution is displaced northward and dark variants predominate. The breeding range of the Gyrfalcon, determined by mapping the locations of the specimens we examined, differs little from the range proposed in 1951.

Journal of Raptor Research↗
USGS1997

Remarkable saker falcon ( Falco cherrug ) breeding records for Mongolia

During 1994-95 surveys, we located over 80 Saker Falcon ( Falco cherrug ) breeding sites in Mongolia. Over half of the sites had features that were in some way remarkable or previously undescribed in the scientific literature. Ten were on utility poles, two on bridges, three on abandoned buildings and one was on a truck tire on a pole. Seven sites were very near buzzard nests and two more were in buzzard nests that were used the same season. Five sites were on cliff tops accessible by walking. Four were on very short cliffs, two were on broken/sloping cliffs and one was at the base of a cliff. Five were on the tops of stone pillars. Six were in very short elm trees. Nest composition was also sometimes remarkable: one was a suspended uric acid (excrement) platform without underlying support, three were trash nests and two were composed largely of bones.

Journal of Raptor Research↗
USGS1998

Caribou antlers as nest materials for golden eagles in northwestern Alaska

There are few published records of antlers in golden eagle (Aquila chrysaetos) nests. This note reports extensive use of caribou (Rangifer tarandus) antlers in three golden eagle nests in the Cape Kruzenstern region of northwestern Alaska. The importance of antlers to this population of eagles can be explained at least in part by (1) the lack of suitable woody vegetation on the open tundra, (2) the similarity of antlers to sticks, and (3) the abundance of antlers, especially cow caribou antlers, in the region.

Journal of Raptor Research↗
USGS1991

The identity of Pennant's 'Wapacuthu owl' and the subspecific name for the population of Bubo virginianus from the western Hudson Bay

The name Strix wapacuthu Gmelin, often used for the subspecies of Bubo virginianus west of Hudson Bay, cannot be associated with certainty with either B. virginianus or Nyctea scandiaca. The subspecific name of the population of B. virginianus from Mackenzie to central-eastern British Columbia and northern Ontario should be B. v. subarcticus Hoy.

Journal of Raptor Research↗
USGS1999

Siblicide, splayed-toes-flight display, and grappling in the Saker Falcon

We observed two incidents of novel social behavior in the saker falcon (Falco cherrug) in Mongolia. First, we provide an account of a two-week-old saker falcon chick killing its nest mate, the first direct observation of siblicide in the genus Falco. We also report aerial combat between three adult saker falcons including observations of talon grappling, whirling, and Splayed-toes-flight, a previously undescribed social display.

Journal of Raptor Research↗
USGS1999

Pronounced variation in tarsal and foot feathering in the upland buzzard (Buteo hemilasius) in Mongolia

During 1994, 1995, 1997, and 1998 expeditions across Mongolia, we located over 250 upland buzzard (Buteo hemilasius) nests. At these, we noted considerable morphological variation in plumage coloration and in leg pterylosis. In 1997 and 1998, we examined 131 nests scattered across eastern and central Mongolia and report here the tarsal condition of 119 nestlings from 59 broods where young were at least 2 weeks of age. Of 119 birds carefully examined, 50 (42%) had less than fully feathered tarsi and 4 of the 69 with fully feathered tarsi had scattered feathers on their toes. Thus, 54 of 119 birds (45%) in some way deviated from the feathered tarsibare toes condition. This extraordinary degree of variability in feather patterns may be best explained as the result of extensive and relatively recent hybridization between the longlegged (Buteo rufinus) and roughlegged (B. lagopus) buzzards and/or between long-legged and upland buzzards.

Journal of Raptor Research↗