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Northern Goshawks (Accipiter gentilis) are a species of special conservation concern in the western Great Lakes bioregion and elsewhere in North America, and exhibit landscape-scale spatial use patterns. However, little information exists about Northern Goshawk habitat relations at broad spatial extents, as most existing published information comes from a few locations of relatively small spatial extent and, in some cases, short durations. We used an information-theoretic approach to evaluate competing hypotheses regarding factors (forest canopy cover, successional stage, and heights of the canopy top and base) related to odds of Northern Goshawk landscape use throughout the western Great Lakes bioregion based on...
Categories: Publication; Types: Citation; Tags: Journal of Raptor Research
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The Common Loon (Gavia immer) must defend against many potential egg predators during incubation, including corvids, Herring Gulls (Larus argentatus), raccoons (Procyon lotor), striped skunk (Mephitis mephitis), fisher (Martes pennanti), and mink (Neovison vison) (McIntyre 1988, Evers 2004, McCann et al. 2005). Bald Eagles (Haliaeetus leucocephalus) have been documented as predators of both adult Common Loons and their chicks (Vliestra and Paruk 1997, Paruk et al. 1999, Erlandson et al. 2007, Piper et al. 2008). In Wisconsin, where nesting Bald Eagles are abundant (>1200 nesting pairs, >1 young/pair/year), field biologists observed four instances of eagle predation of eggs in loon nests during the period 2002–2004...
Categories: Publication; Types: Citation; Tags: Journal of Raptor Research
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Blood samples collected in 1979-81 from wintering Bald Eagles (Haliaeetus leucocephalus) in Oregon and northern California, residents in Oregon, migrants in Montana and residents in Washington were analyzed for lead (Pb), mercury (Hg) and organochlorines. Lead was detected infrequently (5%) and at low concentrations (<0.25 ppm) in nestlings from Oregon, more frequently (41%) and at occasionally elevated concentrations (>0.40 ppm) in wintering Bald Eagles in Oregon and north California and migrants in Montana, and most frequently (56%) in nestlings from Washington but at low concentrations (<0.40 ppm). Mercury concentrations were low (<0.70 ppm) in samples from Washington nestlings and higher in samples from Oregon...
Categories: Publication; Types: Citation; Tags: Journal of Raptor Research
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The Peregrine Fund has published proceedings of several conferences over the years and has become experts, and this 2 volume set is no exception. The title of the proceedings sounded especially interesting in this era of almost daily accounts in the media about climate change, its causes and its effects on the planet, including its flora and fauna. This 772-page Proceedings is loaded with useful information regarding Gyrfalcons and their prey and should be in the library of all serious raptor bibliophiles. The sponsors are to be commended for supporting the conference and for publishing the proceedings. Proceedings are available at http://www.peregrinefund.org/gyr-conf Review info: Gyrfalcons and Ptarmigan in a...
Categories: Publication; Types: Citation; Tags: Journal of Raptor Research
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We studied first-year movements of Mexican Spotted Owls (Strix occidentalis lucida) during natal dispersal in canyonlands of southern Utah. Thirty-one juvenile Mexican Spotted Owls were captured and radiotracked during 1992-95 to examine behavior and conduct experiments related to the onset of natal dispersal. Juvenile Spotted Owls dispersed from their nest areas during September to October each year, with 85% leaving in September. The onset of movements was sudden and juveniles dispersed in varied directions. The median distance from nest area to last observed location was 25.7 km (range = 1.7-92.3 km). Three of 26 juveniles tracked (11%) were alive after one year, although none were observed with mates. We conducted...
Categories: Publication; Types: Citation; Tags: Journal of Raptor Research
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North American Ospreys (Pandion haliaetus) typically migrate long distances to their wintering grounds in the tropics. Beyond the general distribution of their wintering range (i.e., the Caribbean, South America, and Central America), very little is known about the wintering ecology of these birds. We used satellite telemetry to determine the duration of wintering period, to examine the characteristics of wintering areas used by Ospreys, and to quantify space use and activity patterns of wintering Ospreys. Adult Ospreys migrated to wintering sites and exhibited high wintering site fidelity among years. Overall, Ospreys wintered on river systems (50.6%) more than on lakes (19.0%), and use of coastal areas was (30.4%)...
Categories: Publication; Types: Citation; Tags: Journal of Raptor Research
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We reviewed cases of raptor mortality resulting from cholinesterase-inhibiting pesticides. We compiled records from the U.S., U.K. and Canada for the period 1985-95 (520 incidents) and surveyed the relevant literature to identify the main routes of exposure and those products that led to the greatest number of poisoning cases. A high proportion of cases in the U.K. resulted from abusive uses of pesticides (willful poisoning). The proportion was smaller in North America where problems with labeled uses of pesticides were as frequent as abuse cases. Poisoning resulting from labeled use was possible with a large number of granular pesticides and some seed treatments through secondary poisoning or through the ingestion...
Categories: Publication; Types: Citation; Tags: Journal of Raptor Research
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Bald Eagles (Haliaeetus leucocephalus) and geese often occur together, especially at sites used by geese for migrational staging and wintering. Although numerous studies have been directed at these taxa, there are only anecdotal accounts (Parris et al. 1980, Bennett and Klaas 1986, Bartley 1988) of Bald Eagles killing healthy geese at any time of the year (but see Raveling and Zezulak 1991). Most species of geese may be too large, as suggested by Shetrod et al. (1976) and Palmer (1988), or they may not regularly allow eagles an advantageous attack position (J.M. Gerrard in litt.).Here we report observations of attacks on Emperor Geese (Chen canagica) by Bald Eagles on the Alaska Peninsula in autumn. We discuss these...
Categories: Publication; Types: Citation; Tags: Journal of Raptor Research
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Perhaps the best documented example of regular tool use for a falconiform is the Egyptian Vulture (Neophron percnopterus) striking an Ostrich (Struthio camelus) egg with a stone (J. van Lawick-Goodall and H. van Lawick-Goodall 1966, Nature 212:1468-1469; R.K. Brooke 1979, Ostrich 50:257-258). Another species, the Lammergeier (Gypaetus barbatus), routinely drops bones on stone slabs to gain access to the marrow within (L. Brown and D Amadon 1968, Eagles, hawks and falcons of the world, McGraw-Hill, New York, NY U.S.A.). Some, however, would argue that, because the stone is not manipulated, the bone-dropping Lammergeier is not actually using a tool. Another reported example of tool use is the Ferruginous Hawk (Buteo...
Categories: Publication; Types: Citation; Tags: Journal of Raptor Research
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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:...
Categories: Publication; Types: Citation; Tags: Journal of Raptor Research
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Emperor Geese (Chen canagica) are a species of concern because their population has declined rapidly since the mid-1960s and continues to remain below management objectives (Petersen et al. 1994). Emperor Geese are restricted primarily to Alaska and exhibit an east-west migration pattern, whereby most birds begin breeding on the Yukon-Kuskokwim Delta by mid-May, stage on the Alaska Peninsula by late September, and migrate westward to winter in the Aleutian Archipelago from late November to mid-April (Eisenhauer and Kirkpatrick 1977, Petersen et al. 1994). Demographic and movement studies have been conducted on breeding grounds and stagmg areas (e.g., Schmutz et al. 1994, 1997); however, the winter ecology of Emperor...
Categories: Publication; Types: Citation; Tags: Journal of Raptor Research
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We examined the association between the presence of backpack radiotransmitters and Golden Eagle (Aquila chrysaetos) reproduction (percentage of occupied territories producing young, and number of nestlings produced) over three years. The association between radio-tagging and nesting success and the number of nestlings produced varied significantly among years. A negative association with tagging was observed in one of three years, which coincided with low prey (jackrabbit) populations and a cold spring. However, small sample size and breeding by subadults may confound this result.
Categories: Publication; Types: Citation; Tags: Journal of Raptor Research


    map background search result map search result map Reevaluating bald eagle winter roost habitat in Lava Beds National Monument, California Reevaluating bald eagle winter roost habitat in Lava Beds National Monument, California