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Geology topics

S.C. Hess

Publications and source records attributed to S.C. Hess.

7 recordsLinked to original sources
USGS2011

Survival of European mouflon (Artiodactyla: Bovidae) in Hawai'i based on tooth cementum lines

Reliable techniques for estimating age of ungulates are necessary to determine population parameters such as age structure and survival. Techniques that rely on dentition, horn, and facial patterns have limited utility for European mouflon sheep (Ovis gmelini musimon), but tooth cementum lines may offer a useful alternative. Cementum lines may not be reliable outside temperate regions, however, because lack of seasonality in diet may affect annulus formation. We evaluated the utility of tooth cementum lines for estimating age of mouflon in Hawai'i in comparison to dentition. Cementum lines were present in mouflon from Mauna Loa, island of Hawai'i, but were less distinct than in North American sheep. The two age-estimation methods provided similar estimates for individuals aged ???3 yr by dentition (the maximum age estimable by dentition), with exact matches in 51% (18/35) of individuals, and an average difference of 0.8 yr (range 04). Estimates of age from cementum lines were higher than those from dentition in 40% (14/35) and lower in 9% (3/35) of individuals. Discrepancies in age estimates between techniques and between paired tooth samples estimated by cementum lines were related to certainty categories assigned by the clarity of cementum lines, reinforcing the importance of collecting a sufficient number of samples to compensate for samples of lower quality, which in our experience, comprised approximately 22% of teeth. Cementum lines appear to provide relatively accurate age estimates for mouflon in Hawai'i, allow estimating age beyond 3 yr, and they offer more precise estimates than tooth eruption patterns. After constructing an age distribution, we estimated annual survival with a log-linear model to be 0.596 (95% CI 0.5540.642) for this heavily controlled population. ?? 2011 by University of Hawai'i Press.

Pacific Science↗
USGS2011

The history of mammal eradications in Hawai`i and the United States associated islands of the Central Pacific

Many eradications of mammal taxa have been accomplished on United States associated islands of the Central Pacific, beginning in 1910. Commonly eradicated species are rabbits ( Oryctolagus cuniculus ), rats ( Rattus spp.), feral cats ( Felis catus ), and several feral ungulates from smaller islands and fenced natural areas on larger Hawaiian Islands. Vegetation and avifauna have demonstrated dramatic recovery as a direct result of eradications. Techniques of worldwide significance, including the Judas goat method, were refined during these actions. The land area from which ungulates have been eradicated on large Hawaiian Islands is now greater than the total land area of some smaller Hawaiian Islands. Large multi-tenure islands present the greatest challenge to eradication because of conflicting societal interests regarding introduced mammals, mainly sustained-yield hunting. The difficulty of preventing reinvasion poses a persistent threat after eradication, particularly for feral pigs ( Sus scrofa ) on multi-tenure islands. Larger areas and more challenging species are now under consideration for eradication. The recovery of endangered Hawaiian birds may depend on the creation of large predator-proof exclosures on some of the larger islands. Large scale eradications of small Indian mongooses ( Herpestes auropunctatus ) would be beneficial to ground-nesting birds such as nēnē ( Branta sandvicensis ), but this has been achieved only in small exclosures.

Hawaii↗
USGS2010

Design and evaluation of a simple signaling device for live traps

Frequent checks of live traps require enormous amounts of labor and add human scents associated with repeated monitoring, which may reduce capture efficiency. To reduce efforts and increase efficiency, we developed a trap-signaling device with long-distance reception, durability in adverse weather, and ease of transport, deployment, and use. Modifications from previous designs include a normally open magnetic switch and a mounting configuration to maximize reception. The system weighed <225 g, was effective ???17.1 km, and failed in <1% of trap-nights. Employing this system, researchers and wildlife managers may reduce the amount of effort checking traps while improving the welfare of trapped animals.

Journal of Wildlife Management↗
USGS2009

An adaptive strategy for reducing feral cat predation on endangered Hawaiian birds

Despite the long history of Feral Cats Felis catus in Hawai'i, there has been little research to provide strategies to improve control programmes 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, may affect the number of Feral Cats captured at each trap. We used log-link generalized linear models and QAIC c model ranking criteria to determine the effect of these factors. We found that The number of cats captured per trap Was related to 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 M??mane Sophora chrysophylla habitat on the West slope of Mauna Kea, and to cluster traps near others that have previously captured multiple cats.

Hawaii↗
USGS2007

Diet of feral cats in Hawai'i Volcanoes National Park

We documented the diet of feral cats by analysing the contents of 42 digestive tracts from Kilauea and Mauna Loa in Hawai'i Volcanoes National Park. Small mammals, invertebrates, and birds were the most common prey types consumed by feral cats. Birds occurred in 27.8-29.2% of digestive tracts. The total number of bird, small mammal, and invertebrate prey differed between Kilauea and Mauna Loa. On Mauna Loa, significantly more (89%) feral cats consumed small mammals, primarily rodents, than on Kilauea Volcano (50%). Mice ( Mus musculus ) were the major component of the feral cat diet on Mauna Loa, whereas Orthoptera were the major component of the diet on Kilauea. We recovered a mandible set, feathers, and bones of an endangered Hawaiian Petrel ( Pterodroma sandwichensis ) from a digestive tract from Mauna Loa. This specimen represents the first well-documented endangered seabird to be recovered from the digestive tract of a feral cat in Hawai'i and suggests that feral cats prey on this species.

Hawaii↗
USGS2007

Using population genetic tools to develop a control strategy for feral cats (Felis catus) in Hawai'i

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 Hawai'i Island by microsatellite analysis to evaluate genetic diversity and population structure, assess gene flow and connectivity among three populations, identify potential source populations, characterise 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, primarily from Mauna Kea, suggesting that this population should be targeted for control. However, recolonisation 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. Management of other invasive species may benefit by employing these population genetic tools. ?? CSIRO 2007.

Wildlife Research↗