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Full-Text Articles in Life Sciences
Spring Population Estimates Of Rocky Mountain Greater Sandhill Cranes In Colorado, Douglas S. Benning, Roderick C. Drewien, Douglas H. Johnson, Wendy M. Brown, Erwin L. Boeker
Spring Population Estimates Of Rocky Mountain Greater Sandhill Cranes In Colorado, Douglas S. Benning, Roderick C. Drewien, Douglas H. Johnson, Wendy M. Brown, Erwin L. Boeker
Proceedings of the North American Crane Workshop
We developed an aerial survey to estimate the Rocky Mountain Population (RMP) of greater sandhill cranes (Grus canadensis tabidn) (greaters) annually during March 1984-95 in the San Luis Valley, Colorado (SLV). We flew aerial transects covering a 21,220-ha contiguous area. Aerial photographs of crane flocks were taken to correct for estimation errors. We employed ground surveys to correct for presence of lesser sandhill cranes (G. c. canadensis) (lessers), which mixed with RMP cranes. To adjust for RMP cranes not in the survey area, we made ground counts in traditional use areas outside the SLY. During 1984-95, 5 …
Mortality Of Radio-Equipped Sandhill Crane Colts At Malheur National Wildlife Refuge, Oregon, Gary L. Ivey, Eric J. Scheuering
Mortality Of Radio-Equipped Sandhill Crane Colts At Malheur National Wildlife Refuge, Oregon, Gary L. Ivey, Eric J. Scheuering
Proceedings of the North American Crane Workshop
We radio-equipped 142 greater sandhill crane (Grus canadensis tabida) colts at Malheur National Wildlife Refuge, Oregon, during 1991-95 to document prefledging mortality factors. Fates of 19 colts were undetermined. A total of 23 colts survived to fledge (19% of known fates). Evidence collected from the carcasses and death sites indicated that predators were responsible for the largest number of colt deaths (64), followed by unknown causes (13), parasitic gapeworms (Cyastoma spp.) (8), drowning (7), intraspecific aggression (5), study-related mortality (I), roadkill (I), and hay swather (1). Of 64 colts killed by predators, 26 were lost to mink …
Results Of Eight Years Of Predator Control To Enhance Sandhill Crane Production On Malheur National Wildlife Refuge, Oregon, Gary L. Ivey
Results Of Eight Years Of Predator Control To Enhance Sandhill Crane Production On Malheur National Wildlife Refuge, Oregon, Gary L. Ivey
Proceedings of the North American Crane Workshop
Because of a 21 % decline in breeding pairs of greater sandhill cranes (Grus canadensis tabida) on Malheur National Wildlife Refuge from 1971 to 1985, a predator control program was initiated in 1986 to enhance production. The primary cause for the decline was low recruitment of young due to high predation by ravens (Corvus corax). raccoons (Procyon lotor), and coyotes (Canis latrans), On average, predators destroyed 46% of all crane nests and 90% of the prefledged colts. Mink (Mustela vison) were added to the program in 1993 after a study …
Nesting Success And Production Of Greater Sandhill Cranes During Experimental Predator Control At Malheur National Wildlife Refuge, Oregon,1982-83, Carroll D. Littlefield, John E. Cornely
Nesting Success And Production Of Greater Sandhill Cranes During Experimental Predator Control At Malheur National Wildlife Refuge, Oregon,1982-83, Carroll D. Littlefield, John E. Cornely
Proceedings of the North American Crane Workshop
Greater sancfrtill cranes (Grus canadensis tabida) nest commonly on Malheur National Wildlife Refuge, Oregon, but depredations by common ravens (Corvus corax) and coyotes (Canis latrans) contributed substantially to low recruitment during the 1970's. An experimental predator removal study was initiated in 1982 to determine if nesting success and recruitment would increase if predator populations were reduced. We monitored 120 crane nests located in 2 treatment areas (ravens and coyotes removed, and only ravens removed) and 1 control area (40 nests per area). Nesting success between the 2 predator control areas differed significantly during the …
Harts Basin, Colorado: A Spring Migration Stopover Area For Rocky Mountain Sandhill Cranes And Whooping Cranes, Melvin K. Peterson, Roderick C. Drewien
Harts Basin, Colorado: A Spring Migration Stopover Area For Rocky Mountain Sandhill Cranes And Whooping Cranes, Melvin K. Peterson, Roderick C. Drewien
Proceedings of the North American Crane Workshop
Greater sandhill cranes (Grus canadensis tabida) from the Rocky Mountain Population (RMP) and whooping cranes (G. americana) reared by RMP foster parents were monitored during 1980-95 at a traditional spring migration stopover at Harts Basin in western Colorado. Counts during March and April 1986-93 showed that a mean of 10,656 RMP sandhill cranes stopped annually for 1 or more nights en route from their spring staging area in the San Luis Valley, Colorado, to summer grounds. More than 96% stopped between 11 March and 10 April. Count data indicated that > 50 % of the RMP stopped …