Hakalau Forest Birds Project

Effectiveness of potential management actions for increasing populations of endangered birds in wet forests of Hawaii
Pacific Island Ecosystems Research Center, Biological Resources Division, USGS
Principle Investigator: B. L. Woodworth and S. G. Fancy
Research Project Coordinator and Field Project Leader: J. Nelson and M. P. Moore
Field Ornithologists: C. Adler, E. Cohen, C. Driehaus, A. Grover, K. Kozar, S. Langridge, J. Townsend, E. J. Tweed

The high elevation, wet forests on the island of Hawai'i are important habitat for many native Hawaiian honeycreepers, including the endangered 'Akiapola'au (Hemignathus munroi), 'Akepa (Loxops coccineus), and Hawai'i Creeper (Oreomystis mana). These high elevation forests act as refugia from the devastating effects of habitat loss and disease, which have led to the extirpation of most lower-elevation populations. However, wet forest habitats in Hawaii contain high numbers of introduced mammals, most of which are potential predators on birds' nests: black rats (Rattus rattus; picture at right), Polynesian rats (R. exulans), Norway rats (R.), house mice (Mus musculus), feral cats (Felis catus), and mongoose (Herpestes auropunctatus). Of these, the black rat is the most common and arboreal (Atkinson 1985, Lindsey et al. 1999), and thus is potentially a major cause of nesting mortality in wet forest birds.

(Photo by Jack Jeffrey)

rodenticide baiting and trapping techniques

The present study was designed to evaluate the effectiveness of small mammal control for increasing productivity of wet forest passerines in Hawaiian rainforest ecosystems. We used a Before-After-Control-Impact (BACI) design (Stewart-Oaten et al. 1986) and controlled predators in the treatment area using a combination of rodenticide baiting and trapping techniques (picture at left), concentrating our removal efforts on rodents. The study has demonstrated that it is possible to safely remove most predators by poisoning and trapping from native forests through ground-based efforts in key areas. The study has provided recommendations for practical aspects such as spacing of traps and bait stations, how best to monitor the effectiveness of predator removal programs, costs and personnel requirements for predator control work, and optimal timing of predator control efforts. Our ultimate goal was to determine whether ground-based predator control over limited areas would result in measurable increases in forest bird productivity, as measured by mistnetting, censusing, and nesting success studies.

Publications completed:
1. Nelson, J. T., B. L. Woodworth, S. G. Fancy, G. Lindsey, M. P. Moore, and E. J. Tweed. 2002. Effectiveness of rodent control and monitoring techniques for a montane rainforest. Wildl. Soc. Bull. (in press).

Publications in progress:
1. Woodworth, B. L., S. G. Fancy, J. T. Nelson, M. P. Moore, E. J. Tweed, E. B. Cohen, and G. D. Lindsey. Response of forest bird populations to predator control in a Hawaiian rainforest.

Technical reports:
1. Woodworth, B. L., and J. T. Nelson. 1996. Hakalau Forest Birds Project. Report to USFWS Refuges, Oct 1995 to Sept 1996.
2. Woodworth, B. L., and J. T. Nelson. 1997. Hakalau Forest Birds Project. Report to USFWS Refuges, Oct 1996 to Sept 1997.
3. Woodworth, B. L., and J. T. Nelson. 1998. Hakalau Forest Birds Project. Report to USFWS Refuges, Oct 1997 to Sept 1998.
4. Nelson, J. T. and B. L. Woodworth. 1999. Hakalau Forest Birds Project. Report to USFWS Refuges, Oct 1998 to Sept 1999.

Presentations:
1. Fancy, S. G. 1996. Predator control and bird translocations in New Zealand: Implications for Hawaii. Hawaii Conservation Conference, Honolulu Hawaii.
2. Mosher, S. M, S. G. Fancy, G. D. Lindsey, and M. P. Moore. 1996. Predator control in a Hawaiian rainforest. Hawaii Conservation Conference. Honolulu, Hawaii.
3. Woodworth, B. L., S. G. Fancy, M. P. Moore, J. T. Nelson, E. J. Tweed, G. Lindsey, and E. B. Cohen. 1998. Response of forest bird populations to predator control in a Hawaiian Rainforest. Hawaii Conservation Conference, Honolulu, HI.

Forest Bird Project

Hakalau Forest Birds Project

(Photo by Jack Jeffrey)