Survival, movements, and breeding of released Hawaiian geese: An assessment of the reintroduction program

Citation

Black JM, Marshall AP, Gilburn A, Santos N, Hoshide H, Medeiros J, Mello J, Hodges CN & Katahira L (1997) Survival, movements, and breeding of released Hawaiian geese: An assessment of the reintroduction program. Journal of Wildlife Management, 61 (4), pp. 1161-1173. http://www.jstor.org/stable/3802114

Abstract
The Hawaiian goose or nene (Branta sandvicensis) restoration program, initiated in 1949, and with the release of about 2,150 captive-bred birds, has not resulted in a self-sustaining wild population. Results from a capture-recapture analysis indicate that 3 factors affected mortality rates: the year of release, age-class and method of release. Estimated annual mortality ranged from 0 to 87%. Comparisons between sites revealed the unsuitability of some upland sanctuaries as release sites. Hawaiian geese released in the 1960s survived at levels comparable to other wild, healthy goose populations (i.e., between 5 and 16% mortality) until the drought years 1976-83. During this period the majority of captive-reared and released Hawaiian geese (about 1,200) perished. Previously released adults generally survived better than newly released goslings. Birds made temporarily flightless initially to contain them in release pens survived less well than those released before fledging. The upland Hawaiian geese that did survive, did so at areas other than their release site; if they emigrated they survived better, especially during drought years. In all cases movement was away from habitats with dry upper montane-volcanic scrubland to areas with managed grasslands, managed ranchland, or supplemental feed and water. More movements occurred in drought years. Once the geese moved they rarely returned to their release sites. The lowest mortality and highest nest success rates were achieved by geese living at Hawaii Volcanoes and Haleakala National Parks. Hawaiian geese in these areas survived at levels similar to other non-hunted goose populations.

Keywords
Branta sandvicensis; breeding; capture-recapture; emigration; endangered species; Hawaiian goose; mortality; movements; nene; restoration; survival

Journal
Journal of Wildlife Management: Volume 61, Issue 4