Reducing feral cat threats to native wildlife in Hawaii, Technical report HCSU-010

Author:

Hess, Steven, Hansen, Heidi, Banko, Paul C.

Title:

Reducing feral cat threats to native wildlife in Hawaii, Technical report HCSU-010

Periodical:

HCSU technical report

Year:

2008

Subject:

Feral cats Invasive species Predation Habitat conservation Endangered species birds

Summary:

We documented the diet of feral cats (Felis catus) on Kilauea and Mauna Loa within Hawaii Volcanoes National Park (HAVO), determined the incidence of three feline diseases on Mauna Kea, studied feral cat home range, developed and tested trap- signaling devices, tested food-based baits and attractants, analyzed feral cat population dynamics using genetic techniques, and developed an adaptive strategy for reducing predation on endangered Hawaiian birds. Population genetics can provide information about the demographics and dynamics of invasive species that is beneficial for developing effective control strategies. We studied the population genetics of feral cats on Hawaii Island by microsatellite analysis to evaluate genetic diversity and population structure, assess gene flow and connectivity among three populations, identify potential source populations, characterize population dynamics, and evaluate sex-biased dispersal. High genetic diversity, low structure, and high number of migrants per generation supported high gene flow that was not limited spatially. Migration rates revealed that most migration occurred out of West Mauna Kea. Effective population size estimates indicated increasing cat populations despite control efforts. Despite high gene flow, relatedness estimates declined significantly with increased geographic distance and Bayesian assignment tests revealed the presence of three population clusters. Genetic structure and relatedness estimates indicated male-biased dispersal. Mauna Kea may be a source population that can be targeted for control. However, recolonization seems likely given the great dispersal ability that may not be inhibited by barriers such as lava flows. Genetic monitoring will be necessary to assess the effectiveness of future control efforts. Despite the long history of feral cats in Hawaii, there has been little research to provide strategies to improve control programs and reduce depredation on endangered species. Our objective was to develop a predictive model to determine how landscape features on Mauna Kea such as habitat, elevation, and proximity to roads affect the number of feral cats captured at each trap. We used log-link generalized linear models and QAIC(sub c) model ranking criteria to determine the effect of these factors. We found that the number of cats captured per trap was related to trapping effort, habitat type, and whether traps were located on the West or North Slope of Mauna Kea. We recommend an adaptive management strategy to minimize trapping interference by non target small Indian mongoose (Herpestes auropunctatus) with toxicants, to focus trapping efforts in mamane (Sophora chrysophylla) habitat on the West slope of Mauna Kea, and to cluster traps near others that have previously captured multiple cats.

URL:

http://hdl.handle.net/10790/2690

Collection:

Monographs