MORTALITY OF RADIO-EQUIPPED SANDHILL CRANE COLTS AT MALHEUR NATIONAL WILDLIFE REFUGE, OREGON

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...

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Bibliographic Details
Main Authors: Ivey, Gary L., Scheuering, Eric J.
Format: Text
Language:unknown
Published: DigitalCommons@University of Nebraska - Lincoln 1997
Subjects:
greater sandhill crane
Grus canadensis tabida
mortality
Oregon
parasites
predators
radiotelemetry
Animal Sciences
Behavior and Ethology
Biodiversity
Ornithology
Population Biology
Terrestrial and Aquatic Ecology
Circus cyaneus
Aquila chrysaetos
Online Access:https://digitalcommons.unl.edu/nacwgproc/217
https://digitalcommons.unl.edu/context/nacwgproc/article/1217/viewcontent/Ivey___Mortality.pdf
Description
Summary: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 (Mustela vison), 10 to great horned owls (Bubo virginianus), 9 to golden eagles (Aquila chrysaetos), 7 to unidentified predators, 5 to coyotes (Canis latrans), 5 to unidentified raptors, 1 to a northern harrier (Circus cyaneus), and 1 to a raccoon (Procyon lotor). Because mink were the most significant predator, we initiated an experimental mink control program in 1993. Losses from mink in 1993 were reduced to 9%, compared with 36% and 27% in 1991 and 1992, respectively. We concluded that an integrated approach involving habitat management and predator and parasite control could be used to enhance crane productivity.

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