Evaluation of the palatability and toxicity of candidate baits and toxicants for mongooses (\u3ci\u3eHerpestes auropunctatus\u3c/i\u3e)

The small Indian mongoose (Herpestes auropunctatus) is an invasive pest species responsible for damage to native avian, reptile, and amphibian species on Hawaii, Croatia, Mauritius, and several Caribbean Islands, among other regions.Mongoose control has been pursued through a variety of means, with varying success. One toxicant, diphacinone, has been shown to be effective in mongooses and is co-labeled in a rodenticide bait for mongoose control in Hawaii; however, preliminary observations indicate low performance as a mongoose toxicant due likely to poor consumption. We evaluated the efficacy and palatability of 10 commercial rodenticide baits, technical diphacinone powder, and two alternative acute toxicants against mongooses in laboratory feeding trials. We observed poor acceptance and subsequent low overall mortality, of the hard grain-based pellets or block formulations typical of most of the commercial rodenticide baits. The exception was Tomcat® bait blocks containing 0.1% bromethalin, an acute neurotoxin, which achieved up to 100% mortality. Mortality among all other commercial rodenticide formulations ranged from 10 to 50%. Three-day feedings of 0.005% technical diphacinone formulated in fresh minced chicken achieved 100% mortality. One-day feedings of para-aminopropiophenone (PAPP), a chemical that reduces the oxygen-carrying capacity of the blood, achieved 100% mortality at concentrations of 0.10 to 0.15%. Bait acceptance of two sodium nitrite formulations (similar toxic mode of action as PAPP) was relatively poor, and mortality averaged 20%. In general, commercially produced rodenticide baits were not preferred by mongooses and had lower mortality rates compared to freshly prepared meat bait formulations. More palatable baits had higher consumption and achieved higher mortality rates. The diphacinone bait registered for rat and mongoose control in Hawaii achieved 20% mortality and was less effective than some of the other commercial or candidate fresh bait products evaluated in this study

A comparison of plotless density estimators using Monte Carlo simulation on totally enumerated field data sets

<p>Abstract</p> <p>Background</p> <p>Plotless density estimators are those that are based on distance measures rather than counts per unit area (quadrats or plots) to estimate the density of some usually stationary event, e.g. burrow openings, damage to plant stems, etc. These estimators typically use distance measures between events and from random points to events to derive an estimate of density. The error and bias of these estimators for the various spatial patterns found in nature have been examined using simulated populations only. In this study we investigated eight plotless density estimators to determine which were robust across a wide range of data sets from fully mapped field sites. They covered a wide range of situations including animal damage to rice and corn, nest locations, active rodent burrows and distribution of plants. Monte Carlo simulations were applied to sample the data sets, and in all cases the error of the estimate (measured as relative root mean square error) was reduced with increasing sample size. The method of calculation and ease of use in the field were also used to judge the usefulness of the estimator. Estimators were evaluated in their original published forms, although the variable area transect (VAT) and ordered distance methods have been the subjects of optimization studies.</p> <p>Results</p> <p>An estimator that was a compound of three basic distance estimators was found to be robust across all spatial patterns for sample sizes of 25 or greater. The same field methodology can be used either with the basic distance formula or the formula used with the Kendall-Moran estimator in which case a reduction in error may be gained for sample sizes less than 25, however, there is no improvement for larger sample sizes. The variable area transect (VAT) method performed moderately well, is easy to use in the field, and its calculations easy to undertake.</p> <p>Conclusion</p> <p>Plotless density estimators can provide an estimate of density in situations where it would not be practical to layout a plot or quadrat and can in many cases reduce the workload in the field.</p

An Automatic System to Evaluate Bait Station Visitation by Brown Treesnakes and Mongooses

Understanding the temporal, spatial, and behavioral patterns of the free-ranging target species in response to candidate baits and baiting strategies is important to ensure control success. This information can also assist in the development and deployment of feeding stations and can exclude non-target species while constituting effective bait delivery and control strategies for certain invasive animals, especially at environmentally sensitive sites. We used passive integrated transponder (PIT) tags in conjunction with very-high frequency radio-telemetry to remotely record bait station visitations and evaluate bait attractiveness in separate field research studies of brown treesnakes (Boiga irregularis) on Andersen Air Force Base, Guam, Northern Mariana Islands, between 1999 and 2000 and in 2007, for small Indian mongooses (Urva auropunctata: Syn. Herpestes auropunctatus) on Hilo, Hawaiʻi Island, Hawaiʻi. USA. This system allowed us to document visitation rates to bait stations by brown treesnakes and mongooses. In Guam, we determined that 75% of medium to large brown treesnakes (\u3e850 mm snout-vent length [SVL]) attracted to the bait stations consumed toxic bait, while smaller snakes (SVL) were not attracted to the bait stations. On Hawai‘i Island, we learned mongooses foraged over large areas (range = 6.0–70.2 ha), traveled up to 598 m to select baits, had restricted centers of activity, and displayed fidelity to newly discovered food sources. We recorded discrete group feeding activity not previously documented for mongooses. We found that anterior and posterior double-PIT tagging improved detectability of both target species. The complimentary monitoring system we used can be easily adapted for monitoring small mammals, birds, reptiles, or amphibian species and various activities of interest

Development of a Novel Vertebrate Pesticide for the Invasive Small Indian Mongoose

Small Indian mongooses are detrimental introduced predators in the United States, where they depredate native species, serve as vector of disease, and threaten public safety. Due to the risk of accidental introduction to mongoose-free islands, high cost and limitations to trapping, and no national (Section 3) Environmental Protection Agency (EPA)-registered toxicants for mongoose control, there is a need for an efficacious toxic bait for mongooses for use in conservation areas and at points of entry in the United States. Over the last five years, the National Wildlife Research Center (NWRC) worked to develop a toxic bait for mongooses for registration with the EPA. This paper outlines the development pathway to registration of a toxic bait for mongooses in the United States

Analysis of Iophenoxic Acid Analogues in Small Indian Mongoose (\u3ci\u3eHerpestes Auropunctatus\u3c/i\u3e) Sera for Use as an Oral Rabies Vaccination Biological Marker

The small Indian mongoose (Herpestes auropunctatus) is a reservoir of rabies virus (RABV) in Puerto Rico and comprises over 70% of animal rabies cases reported annually. The control of RABV circulation in wildlife reservoirs is typically accomplished by a strategy of oral rabies vaccination (ORV). Currently no wildlife ORV program exists in Puerto Rico. Research into oral rabies vaccines and various bait types for mongooses has been conducted with promising results. Monitoring the success of ORV relies on estimating bait uptake by target species, which typically involves evaluating a change in RABV neutralizing antibodies (RVNA) post vaccination. This strategy may be difficult to interpret in areas with an active wildlife ORV program or in areas where RABV is enzootic and background levels of RVNA are present in reservoir species. In such situations, a biomarker incorporated with the vaccine or the bait matrix may be useful. We offered 16 captive mongooses placebo ORV baits containing ethyl-iophenoxic acid (et-IPA) in concentrations of 0.4% and 1% inside the bait and 0.14% in the external bait matrix. We also offered 12 captive mongooses ORV baits containing methyl-iophenoxic acid (me-IPA) in concentrations of 0.035%, 0.07% and 0.14% in the external bait matrix. We collected a serum sample prior to bait offering and then weekly for up to eight weeks post offering. We extracted Iophenoxic acids from sera into acetonitrile and quantified using liquid chromatography/mass spectrometry. We analyzed sera for et-IPA or me-IPA by liquid chromatography-mass spectrometry. We found adequate marking ability for at least eight and four weeks for et- and me-IPA, respectively. Both IPA derivatives could be suitable for field evaluation of ORV bait uptake in mongooses. Due to the longevity of the marker in mongoose sera, care must be taken to not confound results by using the same IPA derivative during consecutive evaluations

The Path to U.S. National Registration of a Toxic Bait for the Control of the Small Indian Mongoose

The small Indian mongoose (Urva auropunctata [syn. Herpestes auropunctatus]; mongoose) is a highly invasive species in its introduced range that negatively impacts ecosystems. Mongooses depredate native species, serve as a vector of disease posing a risk to human health, and cause sanitation issues in food processing facilities and public areas. Introduced for biocontrol in the late 1800s in Hawaiʻi and the Caribbean, mongooses currently have well-established populations across multiple islands in both island archipelagos and have invaded numerous other locations throughout the world. The concern of accidental introduction to mongoose-free islands, the difficulty in species detection, and the high cost and labor demand of trapping present the need for a novel control method. A target-specific and efficacious toxic bait can provide an additional tool to reduce mongoose abundance, to eradicate incipient populations, and for biocontrol at ports of entry. In this paper, we document the pathway to registration for a toxic bait for mongoose control with the U.S. Environmental Protection Agency. A registered product must demonstrate a low risk to nontarget species, meet standards for human health and safety, and show no unreasonable adverse effects to the environment. There are no other comparable invasive small mammalian carnivores for which toxic baits have been developed and registered for bait station deployment in the United States

Analysis of Iophenoxic Acid Analogues in Small Indian Mongoose (\u3ci\u3eHerpestes Auropunctatus\u3c/i\u3e) Sera for Use as an Oral Rabies Vaccination Biological Marker

The small Indian mongoose (Herpestes auropunctatus) is a reservoir of rabies virus (RABV) in Puerto Rico and comprises over 70% of animal rabies cases reported annually. The control of RABV circulation in wildlife reservoirs is typically accomplished by a strategy of oral rabies vaccination (ORV). Currently no wildlife ORV program exists in Puerto Rico. Research into oral rabies vaccines and various bait types for mongooses has been conducted with promising results. Monitoring the success of ORV relies on estimating bait uptake by target species, which typically involves evaluating a change in RABV neutralizing antibodies (RVNA) post vaccination. This strategy may be difficult to interpret in areas with an active wildlife ORV program or in areas where RABV is enzootic and background levels of RVNA are present in reservoir species. In such situations, a biomarker incorporated with the vaccine or the bait matrix may be useful. We offered 16 captive mongooses placebo ORV baits containing ethyl-iophenoxic acid (et-IPA) in concentrations of 0.4% and 1% inside the bait and 0.14% in the external bait matrix. We also offered 12 captive mongooses ORV baits containing methyl-iophenoxic acid (me-IPA) in concentrations of 0.035%, 0.07% and 0.14% in the external bait matrix. We collected a serum sample prior to bait offering and then weekly for up to eight weeks post offering. We extracted Iophenoxic acids from sera into acetonitrile and quantified using liquid chromatography/mass spectrometry. We analyzed sera for et-IPA or me-IPA by liquid chromatography-mass spectrometry. We found adequate marking ability for at least eight and four weeks for et- and me-IPA, respectively. Both IPA derivatives could be suitable for field evaluation of ORV bait uptake in mongooses. Due to the longevity of the marker in mongoose sera, care must be taken to not confound results by using the same IPA derivative during consecutive evaluations

Diverse examples from managing invasive vertebrate species on inhabited islands of the United States

A wide array of sizes, ecosystems, cultures, and invasive wildlife are represented among inhabited islands. Here, six cases from the United States of America (US) are selected to illustrate the high diversity of invasive animal management issues and objectives. We outline the background, define the problems and management objectives. We identify the management approaches and discuss the results and influences as they specifically relate to inhabited islands. The examples are: (1) Gambian giant pouched rats on Grassy Key, Florida; (2) coqui frogs on Kaua’i, Hawai’i; (3) feral swine on Cayo Costa Island, Florida; (4) rodents and monitor lizards on Cocos Island, Guam; (5) black spiny-tailed iguanas (ctenosaurs) on Gasparilla Island, Florida; and (6) mongooses on Puerto Rico. The outcomes of the programs are discussed, particularly in relation to the impact of human habitation on success