Constraints on productivity of wild Nene or Hawaiian Geese Branta sandvicensis

Abstract

I investigated constraints on the productivity of wild Nene on Hawaii and Maui during 1978-81.  These populations were composed largely of captive-reared birds.  Recruitment of young was low.  Of 140 breeding attempts, 36% resulted in successful nests and 7% produced fledglings.  Annual productivity was limited because:  1) relatively few available pairs attempted to breed (58% on Hawaii; 46% on Maui), 2) average rate of nest success was low (44%), and 3) gosling survival was low (<39%).  Low incidence of nesting suggests that many females could not accumulate sufficient body reserves for egg-laying and incubation due to poor foraging conditions or poorly developed foraging skills.  Nest failure was high due to predation on eggs and incubating females by the introduced mongoose.  Gosling mortality was high because of poor foraging conditions near many nests, forcing broods to travel over rugged, volcanic terrain to distant rearing areas.  In addition, some goslings were killed by predators.  Nene populations would benefit most from improved foraging opportunities for adult females and goslings and from reduced predator populations.