thumbnail

Population trends of forest birds at Hakalau Forest National Wildlife Refuge, Hawai'i

The Condor

By:
, , , , and
DOI: 10.1525/cond.2010.080113

Links

Abstract

The Hakalau Forest National Wildlife Refuge was established to protect native Hawaiian forest birds, particularly endangered species. Management for forest restoration on the refuge has consisted mainly of removing feral ungulates, controlling invasive alien plants, and reforesting former pastures. To assess effects of this habitat improvement for forest birds, we estimated density annually by distance sampling and examined population trends for native and alien passerines over the 21 years since the refuge was established. We examined long-term trends and recent short-term trajectories in three study areas: (1) reforested pastureland, (2) heavily grazed open forest that was recovering, and (3) lightly grazed closed forest that was relatively intact. Three species of native birds and two species of alien birds had colonized the reforested pasture and were increasing. In the open forest, densities of all eight native species were either stable or increasing. Long-term trends for alien birds were also generally stable or increasing. Worryingly, however, during the most recent 9 years, in the open forest trajectories of native species were decreasing or inconclusive, but in the reforested pasture they generally increased. The closed forest was surveyed in only the most recent 9 years, and trajectories of native species there were mixed. Overall, long-term population trends in Hakalau are stable or increasing, contrasting with declines in most other areas of Hawai'i over the same period. However, more recent mixed results may indicate emergent problems for this important bird area.

Study Area

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Population trends of forest birds at Hakalau Forest National Wildlife Refuge, Hawai'i
Series title:
The Condor
DOI:
10.1525/cond.2010.080113
Volume
112
Issue:
2
Year Published:
2010
Language:
English
Publisher:
Cooper Ornithological Society
Publisher location:
Waco, TX
Contributing office(s):
Pacific Island Ecosystems Research Center
Description:
17 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
The Condor
First page:
196
Last page:
212
Country:
United States
State:
Hawai'i
Other Geospatial:
Hakalau Forest National Wildlife Refuge