Are R. Berentsen

Characteristics of white-tailed deer visits to cattle farms: implications for disease transmission at the wildlife–livestock interface

Bovine tuberculosis (bTB) is endemic in free-ranging white-tailed deer (Odocoileus virginianus) in MI, USA. Currently, the rates of farm visitation by deer and co-use of forage resources by cattle and deer are poorly understood. To evaluate the extent deer and livestock may share forage resources, we investigated farm, yard, and cattle-use area visitation by white-tailed deer and compared visitation with common livestock management practices. We fitted 25 female white-tailed deer near the bTB-infected zone in Michigan’s Lower Peninsula with global positioning system collars. Livestock management practices associated with farm visitation included presence of confined feeding pastures, number of cattle water sources, and the number of cattle pastures. Fewer farm visits occurred at night than during the day. A higher proportion of nighttime visits occurred between midnight and sunrise. Visitation to yards and cattle-use areas were similar: a higher proportion of visits occurred at night, and a higher proportion of nighttime visits occurred between midnight and sunrise. Multiple visits during the same day were common. Visitation increased through spring and peaked during the fawning season. Results suggest that mitigation and control efforts to guard against potential transmission of bTB should include the season and time of day during which deer visitation occurs. Furthermore, specific livestock management practices may contribute to farm visitation by deer. Deer visiting multiple farms may contribute to local area spread of bTB. Focusing risk mitigation efforts on individual deer that are most likely to visit farms may reduce potential bTB transmission.

Rabies, canine distemper, and canine parvovirus exposure in large carnivore communities from two Zambian ecosystems.

Disease transmission within and among wild and domestic carnivores can have significant impacts on populations, particularly for threatened and endangered species. We used serology to evaluate potential exposure to rabies virus, canine distemper virus (CDV), and canine parvovirus (CPV) for populations of African lions (Panthera leo), African wild dogs (Lycaon pictus), and spotted hyenas (Crocuta crocuta) in Zambias South Luangwa National Park (SLNP) and Liuwa Plain National Park (LPNP) as well as community lands bordering these areas. In addition, domestic dogs in the study region were evaluated for exposure to CDV and rabies. We provide the first comprehensive disease exposure data for these species in these ecosystems. Twenty-one lions, 20 hyenas, 13 wild dogs, and 38 domestic dogs were sampled across both regions from 2009 to 2011. Laboratory results show 10.5% of domestic dogs, 5.0% of hyenas, and 7.7% of wild dogs sampled were positive for CDV exposure. All lions were negative. Exposure to CPV was 10.0% and 4.8% for hyenas and lions, respectively. All wild dogs were negative, and domestic dogs were not tested due to insufficient serum samples. All species sampled were negative for rabies virus neutralizing antibodies except lions. Forty percent of lions tested positive for rabies virus neutralizing antibodies. Because these lions appeared clinically healthy, this finding is consistent with seroconversion following exposure to rabies antigen. To our knowledge, this finding represents the first ever documentation of rabies virus neutralizing antibodies consistent with rabies exposure that did not lead to clinical disease in free-ranging African lions from this region. With ever-increasing human pressure on these ecosystems, understanding disease transmission dynamics is essential for proper management and conservation of these carnivore species.

Active use of coyotes (Canis latrans) to detect Bovine Tuberculosis in northeastern Michigan, USA.

Bovine tuberculosis (bTB) is endemic in white-tailed deer (Odocoileus virginianus) in northeastern Michigan, USA, and research suggests transmission to cattle. Prevalence of the disease in deer is estimated at 1.8%, but as prevalence decreases the difficulty of detection increases. Research suggests coyotes (Canis latrans) have a higher prevalence of bTB in Michigan than deer and sampling coyotes may be a more efficient surveillance tool to detect presence or spread of the disease. Coyotes possess suitable ecological characteristics to serve as a sentinel species, assuming transmission between coyotes is not significant. The question of whether free-ranging coyotes shed Mycobacterium bovis, the causative agent of bTB, has not been previously addressed. We actively used coyotes as a sentinel to detect bTB in infected and uninfected counties in Michigans Northeastern Lower Peninsula. We determined whether bTB infection was present through bacteriologic culture of lymph nodes and tissues containing lesions and cultured oral/nasal swabs and feces to establish shedding. Seventeen of 171 coyotes were M. bovis culture positive, one of which was from a previously uninfected county. All oral, nasal secretions and feces were culture negative suggesting minimal, if any, shedding of M. bovis. Thus, infection of coyotes is likely to occur through ingestion of infected deer carcasses and not from interaction with conspecifics. These findings support previous research suggesting that coyotes are useful sentinels for bTB. The use of coyotes as a sentinel, may allow wildlife managers to detect the spread of bTB into naïve counties. With earlier detection managers may be able to take proactive surveillance measures to detect the disease in deer and reduce the potential risk to domestic livestock and captive deer herds.

Exposure to Rabies in Small Indian Mongooses (Herpestes auropunctatus) from Two Regions in Puerto Rico

Abstract The small Indian mongoose (Herpestes auropunctatus) was introduced to several Caribbean Islands to control rat (Rattus spp.) damage to sugarcane plantations. Mongooses failed at suppressing rat populations and are now considered pests throughout most of their introduced range. Importantly, mongooses are rabies reservoirs on several Caribbean Islands. In Puerto Rico, mongooses have been implicated in up to 70% of reported animal rabies cases. There is no rabies vaccination program for wildlife in Puerto Rico, and data on rabies in mongooses are limited. We conducted a serosurvey of mongooses in two different ecologic environments in Puerto Rico: El Yunque National Forest and Cabo Rojo National Wildlife Refuge. We collected 119 serum samples from 112 mongooses, 44 (39.3%) of which were positive for rabies virus–neutralizing antibodies. We also collected oral swabs from 147 mongooses, including 88 from which we also collected serum. No oral swabs were positive for rabies virus RNA. Our data support previous research suggesting rabies virus is circulating within the mongoose population on Puerto Rico.

Preference among 7 bait flavors delivered to domestic dogs in Arizona: Implications for oral rabies vaccination on the Navajo Nation

Abstract Less than 20% of the domestic dogs on tribal lands in the United States are vaccinated against rabies. One method to increase vaccination rates may be the distribution of oral rabies vaccines (ORVs). ONRAB® (Artemis Technologies, Inc., Ontario, Canada) is the primary ORV used in Canada to vaccinate striped skunks and raccoons. To investigate the potential use of ONRAB® ORV baits to vaccinate feral domestic dogs against rabies on tribal lands and beyond, we performed a flavor preference study. A total of 7 bait flavors (bacon, cheese, dog food, hazelnut, sugar-vanilla, peanut butter, and sardine) were offered in pairs to 13 domestic dogs. Each dog was offered all possible combinations of bait pairs over a period of 10 days, with each bait offered 6 times. The proportion of times each bait was consumed first by individual dogs was calculated and comparisons among dogs were conducted using the MIXED procedure in SAS (SAS Institute, Cary, NC). Pairwise comparisons between baits were performed using “contrast” statements with sugar-vanilla flavor as the default for comparison. Type 3 tests of fixed effects showed a significant treatment effect (F 6,72 =9.74, P <0.0001). Sugar-vanilla was selected first during 14% of the offerings and exhibited the least preference among all bait types (F 1,72 =22.46, P <0.0001). Dog food was selected first 56% of the time, and more frequently than all other bait types (F 1,72 =13.09, P =0.0005).

Survey of Gastrointestinal Parasite Infection in African Lion (Panthera leo), African Wild Dog (Lycaon pictus) and Spotted Hyaena (Crocuta crocuta) in the Luangwa Valley, Zambia

Little is known about gastrointestinal parasite infections in large carnivores in Africa and what is available is largely from East Africa. We collected faecal samples from nine spotted hyaenas (Crocuta crocuta), 15 lions (Panthera leo) and 13 African wild dog (Lycaon pictus) from Luangwa Valley, Zambia. The most common gastrointestinal parasites found were Isospora spp., Spirometra sp., Taeniidae and Sarcosystis spp. Twenty-eight per cent of all samples were co-infected with Spirometra sp. and Taeniidae, with co-infection rates highest among lions (67%). Thirty-three per cent (3/9) of spotted hyaenas were infected with Isospora sp. Ninety-two per cent (12/13) of wild dog were infected with Sarcocystis, similar to results from studies in South Africa. One lion was infected with a parasite whose morphology suggested Strongyloides sp., not previously been reported in lions. Samples from one lion and two spotted hyaenas yielded no gastrointestinal parasites. Overall, parasite species were consistent with those found from studies in other regions of Africa and are likely a result of ingesting infected prey. To our knowledge this study provides the most comprehensive survey of gastrointestinal parasite infection in large carnivores from this region of Africa to date and provides baseline data for future studies.

Bait Matrix Flavor Preference by Mongoose (Herpestes auropunctatus) in Puerto Rico: Implications for Oral Rabies Vaccination

Abstract The small Indian mongoose (Herpestes auropunctatus) is the primary rabies vector in Puerto Rico. Mongooses are implicated in up to 74% of rabies cases on the island, and pose a threat to domestic animals and human health and safety. No rabies management program exists in Puerto Rico and development of an oral rabies vaccination program requires determining which flavors on the vaccines bait coating matrix that are attractive to mongooses. Our objective was to evaluate preference among three flavors (cheese, coconut and fish) in the Ultralite bait matrix that is used for delivery of Rabies Vaccine, Live Adenovirus Vector (ONRAB®). Placebo baits were offered to free-ranging mongooses in two different ecological environments. The study was conducted at El Yunque National Forest and Cabo Rojo National Wildlife Refuge. At each site we established bait stations with three bait flavors offered simultaneously. We placed a remote camera at each station to monitor bait fate. Cheese ranked higher than fish flavor (W = 1473, P = 0.0273) and cheese and fish both ranked significantly higher than coconut (W = 2180.5, P < 0.0001 and W = 2065.0, P = 0.0008, respectively). These results suggest cheese and fish flavors should perform better than coconut flavor in attracting free-ranging mongooses to consume ONRAB® baits in Puerto Rico.

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

ABSTRACT 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.

Evaluation of the palatability and toxicity of candidate baits and toxicants for mongooses ( Herpestes auropunctatus )

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.

Rodenticide application strategies for intertidal rat habitats

Abstract Context. Successful eradications of invasive rats from islands are paying tremendous conservation dividends, but failed eradications are economically and environmentally costly. For an eradication using rodenticides, every rat in every habitat must have sufficient exposure to toxic bait to receive a lethal dose. A post-operational review of a failed rat eradication on Wake Atoll, central Pacific Ocean, suggested that inadequate treatment of an intertidal habitat within the lagoon might have caused or contributed to the failure to kill all Polynesian rats (Rattus exulans), which have since recovered in number. This habitat could not be treated by aerial broadcast due to concerns about loss of bait to tidal action and perceived contamination of the marine environment. Aims. In preparation for a second attempt, we developed two alternative bait application strategies to distribute enough bait for a long enough period of time to successfully target rats, while minimising bait entering the ocean. Methods. We used camera traps and experimental bait provisioning methods to document rat foraging in the target habitat and uptake of bait. We developed two baiting strategy alternatives, and employed one of these strategies in a placebo bait application to demonstrate bait uptake by rats foraging within this tidally inundated habitat. Key results. Our results show active foraging by rats in the target habitat. Provisioning of placebo bait by various means preventing bait spillage into the marine environment was followed by heavy feeding by rats and minimal bait interference by crabs. Conclusions. We consider it likely that such a bait application strategy will be considered as an alternative during a future eradication attempt on Wake Atoll. Implications. The techniques we explore here will be useful for rodent suppression in other wetland areas requiring rodent control while protecting sensitive aquatic resources.