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Evaluates the use of commercial zinc phosphide baits to reduce rat populations in Hawaiian sugarcane fields. Mortality of black rats and Polynesian rats in laboratory bioassays; Enhancement of the effectiveness of zinc phosphide oat bait by prebaiting with nontoxic grain; Absorption of moisture and physical degradation as reason for rats' reduced acceptance of pellets.

Estimates the relative abundances of the three species of rats--Norway rats (Rattus norvegicus), Polynesian rats (R. exulans) and black rats (R. rattus)--at four Hawaiian sugarcane plantations that historically have received high levels of rodent damage, and quantified various environmental factors that might influence the distribution of these rodents. Methods; Results; Discussion; Research and management implications.

Discusses various aspects of RANDSEL, an interactive computer program used by the National Wildlife Research Center's Hawaii Field Station as a quick and easy method for assigning animals to treatment groups while addressing statistical concerns and meeting regulatory record-keeping requirements. Mechanics of operation; Computer compatibility; Installation; User benefits.

Compares the performance of plotless density estimators (PDE) to obtain clarification of their performance in a diversity of sampling situations. Basic Distance estimators; Batcheler-Bell estimators; Non-parametric estimators; Kendall-Moran estimators; T-square estimators; Ordered Distance estimators; Angle-Order estimators; Variable Area Transect; Quadrat.

Three probabilistic models were developed for characterizing the risk of mortality and subacute coagulopathy to Poouli, an endangered nontarget avian species, in broadcast diphacinone-baited areas on Hawaii, USA. For single-day exposure, the risk of Poouli mortality approaches 0. For 5-d exposure, the mean probability of mortality increased to 3% for adult and 8% for juvenile Poouli populations. For Poouli that consume snails containing diphacinone residues for 14 d, the model predicted increased levels of coagulopathy for 0.42 and 11% of adult and juvenile Poouli populations, respectively. Worst-case deterministic risk characterizations predicted acceptable levels of risk for nonthreatened or endangered species such as northern bobwhite quail and mallards. Also, no acute toxicity was noted for snails and slugs that feed on diphacinone baits. [ABSTRACT FROM AUTHOR]