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Demographics of a Declining Flock of Greater Sandhill Cranes in Oregon
Publication Type: | Journal Article |
Year of Publication: | 1995 |
Authors: | Littlefield, CD |
Journal: | The Wilson Bulletin |
Volume: | 107 |
Issue: | 4 |
Date Published: | 1995 |
ISBN Number: | 00435643 |
Keywords: | Corvidae, Corvus, Corvus corax, Gruidae, Grus, Grus canadensis, Grus grus |
Abstract: | Greater Sandhill Crane (Grus canadensis tabida) nesting success at Malheur National Wildlife Refuge, Harney County, Oregon, was 44% for 456 nests during 1966-1974, and increased to 54% for 640 additional nests during 1976-1989. Predators destroyed 241 (38%) clutches in the 1976-1989 period, with Common Ravens (Corvus corax) taking 63, raccoons (Procyon lotor) 43, coyotes (Canis latrans) 28, and unknown predators 107. Most clutches lost to unknown predators were likely destroyed by coyotes. A total of 52 clutches was either abandoned, flooded, or infertile. The mean annual number of fledged young from 1970-1989 was 31, and mean annual young mortality from hatching to fledging was 84.4%. Of young fledged, a total of 438 broods contained one young and 91 had two (x̄ = 1.14). The 6.7% mean annual recruitment at Malheur between 1970-1989 probably was responsible for a decline in breeding pairs, from 236 in 1975 to 168 in 1989. |
URL: | http://www.jstor.org/stable/4163603 |
Short Title: | The Wilson Bulletin |
Scratchpads developed and conceived by (alphabetical):
Ed Baker,
Katherine Bouton
Alice Heaton
Dimitris Koureas,
Laurence Livermore,
Dave Roberts,
Simon Rycroft,
Ben Scott,
Vince Smith