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During 2019–2020, the Virgin Islands Department of Health investigated potential animal reservoirs of Leptospira spp., the bacteria that cause leptospirosis. In this cross-sectional study, we investigated Leptospira spp. exposure and carriage in the small Indian mongoose (Urva auropunctata, syn: Herpestes auropunctatus), an invasive animal species. This study was conducted across the three main islands of the U.S. Virgin Islands (USVI), which are St. Croix, St. Thomas, and St. John. We used the microscopic agglutination test (MAT), fluorescent antibody test (FAT), real-time polymerase chain reaction (lipl32 rt-PCR), and bacterial culture to evaluate serum and kidney specimens and compared the sensitivity, specificity, positive predictive value, and negative predictive value of these laboratory methods. Mongooses (n = 274) were live-trapped at 31 field sites in ten regions across USVI and humanely euthanized for Leptospira spp. testing. Bacterial isolates were sequenced and evaluated for species and phylogenetic analysis using the ppk gene. Anti-Leptospira spp. antibodies were detected in 34% (87/256) of mongooses. Reactions were observed with the following serogroups: Sejroe, Icterohaemorrhagiae, Pyrogenes, Mini, Cynopteri, Australis, Hebdomadis, Autumnalis, Mankarso, Pomona, and Ballum. Of the kidney specimens examined, 5.8% (16/270) were FAT-positive, 10% (27/274) were culture-positive, and 12.4% (34/274) were positive by rt-PCR. Of the Leptospira spp. isolated from mongooses, 25 were L. borgpetersenii, one was L. interrogans, and one was L. kirschneri. Positive predictive values of FAT and rt-PCR testing for predicting successful isolation of Leptospira by culture were 88% and 65%, respectively. The isolation and identification of Leptospira spp. in mongooses highlights the potential role of mongooses as a wildlife reservoir of leptospirosis; mongooses could be a source of Leptospira spp. infections for other wildlife, domestic animals, and humans., Author summary Leptospirosis is a zoonotic disease caused by bacteria of the genus Leptospira. To better understand local reservoirs and risk factors to humans and animals, during 2019–2020, the Virgin Islands Department of Health (VIDOH) investigated Leptospira spp. in association with the small Indian mongoose (Urva auropunctata, syn: Herpestes auropunctatus) across the three main islands of the United States Virgin Islands (USVI) (St. Croix, St. Thomas, and St. John). Mongoose blood and kidney samples were evaluated by laboratory testing: microscopic agglutination test, fluorescent antibody test (FAT), real-time polymerase chain reaction (lipl32 rt-PCR), and culture. Of 256 mongooses, 34% were exposed to Leptospira spp. To assess active infection in mongooses, kidney samples were examined resulting 5.8% (16/270) FAT-positive, 10% (27/274) culture-positive, and 12.4% (34/274) rt-PCR-positive. Validity was compared between test types showing higher positive predictive value for FAT and rt-PCR testing for predicting successful culture, the reference standard for diagnosis. Through the detection and isolation of Leptospira spp. in mongooses across the USVI, we identified mongooses as potential disease vectors to the local population and added to the limited data for the Caribbean region. Furthermore, a validity assessment of reference testing provides data to potentially inform future leptospirosis diagnostics.

Mongooses, a nonnative species, are a known reservoir of rabies virus in the Caribbean region. A cross-sectional study of mongooses at 41 field sites on the US Virgin Islands of St. Croix, St. John, and St. Thomas captured 312 mongooses (32% capture rate). We determined the absence of rabies virus by antigen testing and rabies virus exposure by antibody testing in mongoose populations on all three islands. USVI is the first Caribbean state to determine freedom-from-rabies for its mongoose populations with a scientifically-led robust cross-sectional study. Ongoing surveillance activities will determine if other domestic and wildlife populations in USVI are rabies-free., Author summary Mongooses in the Caribbean region are known to carry rabies and infect and kill humans with the deadly virus. While many countries in the Caribbean region assume they are rabies-free, there is a lack of scientifically based surveillance. We prospectively designed a statistically valid study to determine that mongoose populations in the US Virgin Islands are rabies-free and pose no risk of transmission to human or animal populations. We are pursuing further surveillance efforts to establish rabies freedom in all wildlife and domestic animal population in the US Virgin Islands.

The Ontario Rabies Vaccine (ONRAB) is a human adenovirus rabies glycoprotein recombinant oral vaccine immunogenic for small Indian mongooses when delivered by direct instillation into the oral cavity. We offered Ultralite baits containing ~1.8 mL 109.5 TCID50 ONRAB oral rabies vaccine to 18 mongooses, while 6 mongooses were offered identical baits in placebo form. We collected sera from individual mongooses at days 0, 14 and 30 post vaccination (pv) and quantified rabies virus neutralizing antibodies (RVNA) using the rapid fluorescent focus inhibition test, with titers greater than or equal to 0.1 IU/mL considered positive. All study subjects were RVNA negative prior to bait offering. Bait consumption was variable: all 6 sham and 13 of 18 (72%) treatment animals consumed/punctured the baits offered. By day 30 pv, RVNA were detected among 11 of 13 (84.6%) of treatment mongooses that consumed/punctured baits, whereas sham-vaccinated mongooses remained RVNA negative throughout the study. We conclude ONRAB is immunogenic for mongooses by Ultralite bait delivery, although the bait design may need further optimization.

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 hig...

Seroprevalence of rabies virus neutralizing antibodies (rVNA) in raccoons (Procyon lotor) following oral rabies vaccination (ORV) with RABORAL V-RG® in the United States has annually averaged 30% since 1997, a level that is unlikely to successfully interrupt rabies transmission in raccoon populations. A longitudinal ORV zone is maintained in the eastern United States with raccoon variant rabies established east of the zone but absent to the west. However, questions remain regarding the effect of the bait application strategy towards achieving optimal population immunity. We estimated the number of ORV baits/km2 of raccoon home range and calculated rVNA seroprevalence following 2 ORV baiting strategies: cluster baiting (≤10 baits dropped at a time) via helicopter and hand distribution of individual baits at regular intervals along roads and trails in suburban Chattanooga, Tennessee, USA, during fall 2013 and 2014. We applied baits at 75 baits/km2 under both strategies. We established 6 1-km2 cells in each treatment area, and fitted ≤2 raccoons with global positioning system collars in each cell. We trapped and sampled ≤25 raccoons in each study cell pre- and post-ORV application for rVNA analysis. Overall raccoon home range and core area estimates were 80.7 ha and 17.5 ha, respectively (n = 36). Average bait application for home ranges (n = 32 home ranges that received bait) was 80.9 baits/km2 for helicopter baiting and 63.6 baits/km2 for hand baiting sites. Average bait application for core areas was 104.7 baits/km2 for helicopter baiting and 69.2 baits/km2 for hand baiting sites. All home ranges were baited in both treatment areas, whereas 10/18 and 13/14 core areas were baited in the helicopter and hand distribution sites, respectively. Overall, helicopter cluster ORV delivered more baits/km2 of raccoon home range than hand distribution but was less effective in reaching core areas. Seroprevalence did not change as a function of baiting strategy (helicopter vs. hand baiting). The average overall increase in seroprevalence following ORV application was 8.9%. Evaluation of additional strategies are needed because both methods failed to achieve herd immunity necessary to disrupt rabies transmission in raccoons. © 2017 The Wildlife Society.

The small Indian mongoose (

Oral rabies vaccination is the principal strategy used to control rabies in wildlife. No oral rabies vaccine is licensed for small Indian mongooses (

Rabies is responsible for an estimated 59,000 human deaths worldwide, and domestic dogs are the primary reservoir and vector of the disease. Among some nations, widespread vaccination has led to elimination of rabies in domestic dogs, yet dogs are still susceptible to rabies infection from interactions with wildlife reservoirs. On Tribal lands in the United States, less than 20% of domestic dogs are vaccinated for rabies, and parenteral vaccination is often unfeasible. Oral rabies vaccination may provide a solution, but a suitable bait flavor and vaccine must be identified. We evaluated 5 bait flavors (bacon, cheese, egg, fish, and sweet) in pairwise flavor-preference trials using placebo Ultralite baits in 26 domestic dogs on the Navajo Nation, Arizona. Each bait flavor was offered a total of 104 times. In all paired comparisons, bacon was more frequently preferred to the alternative. The sweet flavor (the flavor used operationally for oral rabies vaccine (ORV) distribution in Canada) was least preferred. Forty domestic dogs were offered baits containing ONRAB ORV: 14 received the sweet-flavored bait packet and 26 received bacon-flavored baits. Serum was collected from dogs before vaccination and at day 14 and 30 or 37 days after vaccination. Thirty-seven dogs consumed the baits, 2 baits (both sweet flavored) were chewed and spit out, and 1 (sweet flavored) was swallowed without apparent chewing (gulped). Eight dogs had preexisting rabies virus neutralizing antibody (RVNA) titers and 13 naive dogs failed to seroconvert during the study period. Overall, 27 dogs (67.5%) showed increased RVNA titers after vaccination, including 1 dog who chewed and spit out the bait and all dogs with positive baseline RVNA titers. Geometric mean titers for all dogs that seroconverted during the study period peaked at day 14 (1.2 IU/mL; n = 24) and decreased slightly by the final sampling day (0.8 IU/mL; n = 27). We conclude that bacon flavor may be a suitable bait flavor for ORV distribution in loosely kept or free-roaming domestic dogs. Seroconversion among dogs who ingested ONRAB-filled baits was variable. Why 13 dogs who consumed ORV baits failed to seroconvert remains unknown. Additional research to improve seroconversion rates in domestic dogs after vaccination with ONRAB is recommended.

The small Indian mongoose (Urva auropunctata) is an opportunistic omnivore introduced to sugar producing islands primarily to control rat (Rattus spp.) populations, yet is now considered an invasive pest species on multiple Caribbean islands. Data on home range estimates of mongooses in Puerto Rico and other regions are limited. We fitted 24 mongooses (15 males and nine females) with very high frequency (VHF) radio collars at the Cabo Rojo National Wildlife Refuge in southwestern Puerto Rico and tracked them via radio telemetry for up to six months. The raw mean (SE) minimum convex polygon home range among 24 mongooses was 45.03 (8.30) hectares. The mean (SE) fixed kernel 95% estimate was 38.37 (5.78) hectares, and the 50% core area estimate was 7.89 (1.29) hectares. Our home range estimates are similar to previous estimates in the Caribbean and other islands, but larger than those reported from their native range in India. Our study adds new information to the small body of literature available on mongoose home ranges and is one of the few studies conducted in a lowland dry semi-deciduous forest in southwestern Puerto Rico. Additional research on mongoose home ranges in suburban/rural habitats, as well as in agricultural areas, would provide valuable information for the management of wildlife disease and damage conflicts associated with mongooses in the Caribbean region.

The small Indian mongoose (Urva aurpunctata) is a non-indigenous wildlife reservoir for rabies virus on several Caribbean islands. Oral rabies vaccination (ORV) has been suggested to prevent the spread of rabies in mongooses, but there are limited data on ORV bait survival in maritime/tropical climates. We compared disappearance rates of an egg-flavored bait block vs. a control (canned tuna) and for bait blocks, we assessed if season, habitat, and day/night would influence the disappearance rate. On the island of St. Kitts, West Indies, we baited 45 stations (n=35 bait blocks, n=10 controls) at dawn and checked them twice daily for 4 consecutive days. This procedure was repeated after a two-day period, for each combination of season (dry and wet) and habitat type (mixed grassland, littoral and dry forest). We used the Kaplan-Meier method to estimate bait survival at 12 and 36 hours after baiting. Across all sites, control baits were removed faster than bait blocks, but by 36 hours, over 90% of all baits had disappeared. For bait blocks only, the disappearance rate was higher during the dry season and in the dry forest habitat compared to the other habitats. There was no difference between diurnal and nocturnal disappearance rates. While the exact species that consumed the baits remain uncertain, we found that mongooses readily remove bait blocks, along with non-native mammals (e.g., dogs and cats) and land crabs in littoral habitats. We suggest that the bait blocks used in this study may be suitable for use as an external bait matrix for ORV baits.

Raccoon rabies in eastern USA is managed by strategically distributing oral rabies vaccine (ORV) baits. The attractiveness, palativity, density, and non-target species bait take affect ORV effectiveness. We examined raccoon and non-target species differences in investigating/removing fish-meal polymer and coated sachet baits applied to simulate two aerial bait distribution densities. Bait densities of 150 baits/km2 and 75 baits/km2 were evaluated, respectively, in zones expected to have high and low raccoon densities. Three primary non-target species visited baits: coyotes, white-tailed deer, and feral swine. The proportion of bait stations visited by raccoons during 1 week observation periods ranged from 50 to 70%, exceeding non-target species visitation. Raccoon take rates for visited baits averaged from 59 to 100%. Raccoon visitation was similar for both bait densities, indicating a proportionally greater quantity of baits were taken in the higher bait density zone. Coyote visitation rates ranged from 16 to 26%, with take rates for visited baits between 46 and 100%. Coyotes were expected to take baits intended for raccoons, because similar baits are applied to vaccinate coyotes. Deer regularly investigated but rarely took baits. Feral swine were in low abundance in the high bait density zone (higher human density) and visited ≤ 1% of baits there but visited baits at frequencies similar to coyotes and deer in the low-density zone and were likely to take encountered baits (63–100%). Non-target bait consumption could be a concern in some circumstances for achieving sufficient raccoon sero-conversion rates.

ThesmallIndianmongoose(Herpestesauropunctatus)isaninvasivespeciesandrabiesreservoirin Puerto Rico. In the continental United States, terrestrial wildlife rabies is primarily managed by the National Rabies Management Program (NRMP) of the United States Department of Agriculture through oral rabies vaccination (ORV); the distribution of the vaccine baits is influenced by the population density of the target species.TheNRMPusesadensityindexforestimatingraccoon(Procyonlotor)populationdensitytoguidebait distribution. In Puerto Rico, a wildlife rabies vaccination program does not exist and vaccination of domestic animals is limited and not compulsory. To acquire information on density and other population dynamics, we compared a mongoose density index (MDI) adapted from the NRMP raccoon density index (RDI) to 3 other methods (2 types of capture-mark-recapture (CAPTURE and MARK) and spatially explicit capture-recapture (SECR)) for estimating density that incorporate modeling procedures on detection probabilities, and examined the spatial distribution of mongooses within our study plots. We used the RDI trapping protocol modified for mongooses to livetrap mongooses in El Yunque National Forest (El Yunque) andCaboRojoNationalWildlifeRefuge(CaboRojo)infallof2011andspringof2012resultingin4trapping sessions. The MDI estimates were consistently less than those from other methods for estimating mongoose densities.The MDIdetecteda greatermongoosedensityduringthewetseason(0.55mongooses/ha)thanthe dryseason(0.34mongooses/ha)atCaboRojo,consistentwithall3otherdensityestimationmethods.Overall, the correlation coefficient between MDI and the other calculation methods was � 0.68. When we examined known locations of mongooses and travel distances, we detected more mongooses in a smaller area within the study plot at Cabo Rojo than at El Yunque. The MDI provided information on the spatial distribution of mongooses, which will be needed to implement an ORV program to target mongooses in Puerto Rico. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

The use of rodenticides to control or eradicate invasive rats (Rattus spp.) for conservation purposes has rapidly grown in the past decades, especially on islands. The non-target consequences and the fate of toxicant residue from such rodent eradication operations have not been well explored. In a cooperative effort, we monitored the application of a rodenticide, ‘Brodifacoum 25W: Conservation’, during an attempt to eradicate Rattus rattus from Palmyra Atoll. In 2011, Brodifacoum 25W: Conservation was aerially broadcasted twice over the entire atoll (2.5 km 2 ) at rates of 80 kg/ha and 75 kg/ha and a supplemental hand broadcast application (71.6 kg/ha) occurred three weeks after the second aerial application over a 10 ha area. We documented brodifacoum residues in soil, water, and biota, and documented mortality of non-target organisms. Some bait (14–19% of the target application rate) entered the marine environment to distances 7 m from the shore. After the application commenced, carcasses of 84 animals representing 15 species of birds, fish, reptiles and invertebrates were collected opportunistically as potential non-target mortalities. In addition, fish, reptiles, and invertebrates were systematically collected for residue analysis. Brodifacoum residues were detected in most (84.3%) of the animal samples analyzed. Although detection of residues in samples was anticipated, the extent and concentrations in many parts of the food web were greater than expected. Risk assessments should carefully consider application rates and entire food webs prior to operations using rodenticides.

Rats ( Rattus spp.) are among the most damaging invasive species worldwide. The accidental introduction of rats has caused significant detriment to native flora and fauna, crops, structures, and human livelihoods. Rats are vectors of disease and carriers of various zoonotic parasites. Capillaria hepatica (syn. Callodium hepaticum) is a parasitic nematode found primarily in rodents but is known to infect over 140 mammal species, including human beings and several species of domestic animals. In this case study, the presence of C. hepatica infection in black rats on Diego Garcia, British Indian Ocean Territory, is reported. Liver samples from 20 black rats ( Rattus rattus) were collected during a concurrent population density estimation study. Histology revealed 15 (75%) of the rats sampled had a current or previous infection with C. hepatica. In addition, a larval cestode compatible in size and shape with Cysticercus fasciolaris, the larval stage of Taenia taeniaeformis of cats, was found in 3 (15%) of the rats sampled. The high prevalence of C. hepatica infection in rats on Diego Garcia has implications for human health given the high population density of rats found on the island.

Selection of preferred baits to attract mongooses to traps and other control devices is paramount in the effective management and control of this invasive predatory mammal. We examined the attractiveness of selected food items as baits to free-ranging mongooses in field trials at two different habitats on the island of Hawaii. We utilized radio telemetry to calculate mongoose home range and population density estimates. We implanted microchips to remotely identify and record visitations by mongooses to the candidate baits and investigated bait visitation rates, bait attraction distances, and bait discovery times. Mongooses in this study foraged over a wide area and readily investigated the various novel food baits, with fish, beef and egg-baited stations eliciting higher first and revisits over multiple days. We radio collared 34 mongooses. Overall mean home range estimates were 21.9 and 28.8 ha and did not differ between the two study sites (F = 2.12, p = 0.156), although overall male mongooses had larger home ranges than females (F = 22.92, df = 1, p

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.

The small Indian mongoose (Herpestes auropunctatus) is a rabies reservoir in areas of the Caribbean including Puerto Rico, but no rabies vaccination program targeting this host exists. We used two derivatives of iophenoxic acid (IPA) to evaluate placebo oral rabies vaccine bait uptake by mongooses in southwestern Puerto Rico. We hand-distributed baits at an application rate of 200 baits/km2 at three, 400 ha, sites during autumn 2016 and spring 2017. Each site contained 90-100 cage traps in a 100 ha central trapping area. We used ethyl-IPA as a biological marker during the autumn and methyl-IPA during the spring. We live captured mongooses for 10 consecutive days, beginning 1 wk following bait application. We obtained a serum sample from captured mongooses and analyzed the sera for ethyl- and methyl-IPA by liquid chromatography-mass spectrometry. During autumn 2016, 63% (55/87) mongooses sampled were positive for ethyl-IPA. In spring 2017, 69% (85/123) of mongooses were positive for methyl-IPA. Pooling seasons, accounting for recaptures between years, and disregarding marker type, 74% (133/179) unique mongooses were positive for IPA biomarker, indicating bait consumption during either the autumn, spring, or both trials. We conclude that distributing baits at an application rate of 200 baits/km2 is sufficient to reach over 60% of the target mongoose population in dry forest habitats of Puerto Rico.

Oral rabies vaccination is the principal strategy used to control rabies in wildlife. No oral rabies vaccine is licensed for small Indian mongooses (Herpestes auropunctatus). The Ontario Rabies Vaccine Bait (ONRAB) is a human adenovirus type-5 rabies glycoprotein recombinant vaccine licensed for rabies control in striped skunks (Mephitis mephitis) in Canada and is under experimental evaluation in the US. We evaluated varying doses of ONRAB vaccine by direct instillation into the oral cavity with three groups of 10 mongooses: Group 1 received 109.5 TCID50, group 2 received 108.8 TCID50, and group 3 received 108.5 TCID50 of vaccine. Six control mongooses were sham-vaccinated with culture media. We collected a serum sample prior to vaccination and on days 14 and 30 postvaccination (PV). We quantified the level of rabies virus neutralizing antibodies (RVNA) from mongoose sera and compared titers among vaccinated groups and time points PV, where values greater than or equal to 0.1 IU/mL were considered positive. On day 14 PV, 87% (26 of 30, 95% confidence interval 70-95%) of vaccinates had seroconverted, whereas all vaccinates demonstrated RVNA by day 30 PV. There was a marginal effect of vaccine dose on group means of log-transformed RVNA titers at day 14 PV (F=2.5, P=0.099), but not day 30 PV. Sham-vaccinated animals were seronegative during all time points.

The spread of rabies in terrestrial wildlife throughout the United States is primarily controlled through oral rabies vaccination. Relatively low bait acceptance and seroconversion rates by some target species have prompted investigation into an alternative to the RABORAL V-RG bait currently used. In Canada, ONRAB Ultralite baits are used to vaccinate raccoons (Procyon lotor) and striped skunks (Mephitis mephitis). Comparative studies between RABORAL V-RG and ONRAB found higher seroconversion rates among raccoons that ingested ONRAB, suggesting that it may be a suitable alternative. However, ONRAB has not been evaluated in many rabies reservoir species, including coyotes (Canis latrans). Vaccination of coyotes is a critical element in preventing reemergence of canine strain of rabies in the United States. We evaluated flavor preference of ONRAB Ultralite oral rabies vaccine baits by coyotes. Preferences among bait types differed (Friedman c 2 ¼ 13.28; df ¼ 5; P ¼ 0.02). Of the 6 bait flavors evaluated, cheese ranked the highest, followed by fish, chicken, sugar-vanilla, egg, and bacon flavors. Pairwise trials among the top 3 flavors (cheese, fish, and chicken) showed no difference (Friedman c 2 ¼ 3.00; df ¼ 2; P ¼ 0.22). Our

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 vaccine's 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.

A molecular survey was conducted for several hemoparasites of domestic dogs and three species of wild carnivores from two sites in Zambia. Three Babesia spp. were detected including Babesia felis and Babesia leo in lions (Panthera leo) and a Babesia sp. (similar to Babesia lengau) in spotted hyenas (Crocuta crocuta) and a single lion. All wild dogs (Lycaon pictus) and domestic dogs were negative for Babesia. High prevalences for Hepatozoon were noted in all three wild carnivores (38–61 %) and in domestic dogs (13 %). Significantly higher prevalences were noted in hyenas and wild dogs compared with domestic dogs and lions. All carnivores were PCR negative for Ehrlichia canis, Ehrlichia ewingii, and Bartonella spp. Overall, high prevalences and diversity of Babesia and Hepatozoon were noted in wild carnivores from Zambia. This study is the first molecular characterization of Babesia from any hyena species and is the first report of a Babesia sp. closely related to B. lengau, a parasite previously only reported from cheetahs (Acinonyx jubatus), in lions and hyenas. Although usually benign in wild carnivores, these hemoparasites can be pathogenic under certain circumstances. Importantly, data on vectors for these parasites are lacking, so studies are needed to identify vectors as well as determine transmission routes, infection dynamics, and host specificity of these hemoparasites in wildlife in Africa and also the risk of transmission between domestic animals and wildlife.

Bovine tuberculosis (bTB) is endemic in free- ranging white-tailed deer (Odocoileus virginianus )i n MI, USA. Currently, the rates of farm visitation by deer and co- use of forage resources by cattle and deer are poorly under- stood. 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, num- ber 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 mid- night 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 mid- night and sunrise. Multiple visits during the same day were common. Visitation increased through spring and peaked dur- ing 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 visit- ing 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.

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.

Bovine tuberculosis (bTB) is endemic in white-tailed deer (Odocoileus virginianus )i n 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 Michigan's 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 naive 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. Published by Elsevier B.V.

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.

The coyote lure operative device (CLOD) is a substance delivery system for coyotes (Canis latrans). Field testing has demonstrated that free-ranging coyotes will activate CLODs, but whether individual animals or mated pairs will do so repeatedly has not been examined. We conducted 2 experiments with captive coyotes to determine whether individual animals or mated pairs would approach and activate CLODs repeatedly when exposed to them in a familiar environment over 4 consecutive days. The second experiment allowed us to determine whether a bias existed toward either member of a pair when CLODs were activated. We concluded that individuals and mated pairs approach and activate CLODs with decreased latency over a 4-day testing period. Both sexes activated CLODs when encountered as individuals, but males activated more CLODs than females when mated pairs were exposed to the device. These results imply that an end user of the CLOD can wait until regular “take” occurs before introducing an active ingre...

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 (F6,72 = 9.74, P

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.

Author(s): Vogt, Scott; Vice, Daniel S.; Pitt, William C.; Guzman, Antenor Nestor; Necessario, Ernesto J.; Berentsen, Are R. | Abstract: Introduced black rats are among the most invasive species to islands worldwide. In addition to agricultural impacts, rats are vectors of disease, cause damage to native flora and fauna, and negatively impact threatened/endangered species. Eradication efforts have met with mixed success. Success or failure of an eradication effort can depend on the population density of the target species, which can influence rodenticide sowing rates. We used snap trapping grids to estimate black rat densities in two different forest types on Diego Garcia: coconut forest and mixed species forest. Individual snap traps baited with fresh coconut were placed every 10 m in a 100-m × 100-m (1 ha) grid in the mixed forest and every 20 m in a 220-m × 220-m grid (4.8 ha) in the coconut forest. Traps were checked twice daily for 7 and 11 days in the mixed and coconut forest, respectively. In total, 914 rats were captured on the coconut forest grid and 125 rats were captured on the mixed forest grid. Rat density in coconut forest was 187 rats/ha (95% CI: 176-201) and 88 rats/ha (95% CI: 82-104) in mixed forest. Stomach contents were examined in 121 rats trapped in the mixed forest: 81% contained coconut along with other vegetation or meat, and 67% contained coconut exclusively. It is likely that the high rat density is driven by an abundant coconut food source resulting in a variable distribution of rats among habitat types. Planning for eradication will need to consider the variability of rodent densities across different habitats, with management strategies developed to address this variability.

Author(s): Van Vuren, Dirk H.; Ordenana, Miguel A.; McGrann, Michael C. C.; Berentsen, Are R. | Abstract: Burrowing mammals such as ground squirrels are considered threats to levee integrity, and some authors have proposed that ground squirrel occurrence on levees might be reduced by habitat modification. We characterized the threat that California ground squirrels pose to levees by summarizing available information on burrow lengths and depths, and we reviewed available information about the efficacy of habitat modification to reduce squirrel occurrence on levees. Burrows of California ground squirrels averaged 8.2 m in length (range = 0.9-42.1 m) and 75 cm in greatest depth (range = 33-168 cm), indicating that most burrows are not long enough to transect most levees but nonetheless could contribute to “piping” of water through the levee and create voids that trigger collapses of levee soil. There is little evidence that managing for either short-stature grassland or shrubby vegetation on levees will reduce occurrence of ground squirrels, but further research is needed for both approaches. Managing for trees on levees likely will reduce the occurrence of ground squirrels, probably because tree-covered habitats create visual obstruction that is avoided by ground squirrels. The presence of nut and fruit crops adjacent to levees increases the occurrence of ground squirrels on the levee, probably because these crops provide a rich food resource.

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 Zambia's 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.

Invasive rodents (primarily Rattus spp.) are responsible for loss of biodiversity in island ecosystems worldwide. Large-scale rodenticide applications are typically used to eradicate rats and restore ecological communities. In tropical ecosystems, environmental conditions rapidly degrade baits and competition for baits by non-target animals can result in eradication failure. Our objective was to evaluate persistence of rodenticide baits during a rat eradication program on Palmyra Atoll; a remote tropical atoll with intense competition for resources by land crabs. Following aerial application, bait condition was monitored in four terrestrial environments and in the canopy foliage of coconut palms. Ten circular PVC hoops were fixed in place in each of Palmyra's four primary terrestrial habitats and five rodenticide pellets were placed in each hoop. Five coconut palms were selected in three distinct regions of the atoll. One rodenticide pellet was placed on each of five palm fronds in each coconut palm. Fresh baits were placed in all monitoring locations after each broadcast bait application. Bait condition and survival was monitored for 7 days after the first bait application and 6 days after second application. Bait survival curves differed between applications at most monitoring sites, suggesting a decrease in overall rat activity as a result of rodenticide treatment. One terrestrial site showed near 100 % bait survival after both applications, likely due to low localized rat and crab densities. Median days to pellet disappearance were one and two days for the first and second application, respectively. Differences in survival curves were not detected in canopy sites between bait applications. Median days to pellet disappearance in canopy sites were 2 and 4 days for the first and second application, respectively. Frequent rainfall likely contributed to rapid degradation of bait pellets in coconut palm fronds.

Baits containing brodifacoum rodenticide were aerially applied to eradicate invasive black rats from Palmyra Atoll, an important biodiversity center. Bait application must be sufficient to be effective, while minimizing environmental hazards by not exceeding designated label rates, prompting our bait density assessments for two aerial drops. With few physical or human resources on this remote, uninhabited atoll, assessments were particularly challenging, requiring observations within 30 min of aerial application to avoid bait loss to rats, crabs, or elements. We estimated bait density using quadrat sampling within 13 terrestrial sampling areas. We also sampled 10 tidal flat areas to assess inadvertent bait scatter into marine aquatic environments. Of particular value for challenging sampling circumstances, our quadrats had to be lightweight and durable, which we addressed by using widely available PVC hoops ("Hula Hoops"), the size of which was ideal for sampling purposes. At 77.5 and 78.7 kg/ha, overall bait densities were very near to the target densities of 80 and 75 kg/ha, respectively. However, considerable variability in bait densities existed among sampled areas, 8.6-178.2 and 31.4-129.5 kg/ha for the respective drops, respectively. Environmental, human, and equipment factors likely accounted for this variability. Tidal flat sampling revealed variable bait scatter into aquatic environments, from 0-46.3 kg/ha across the two drops. No differences were found in average bait densities among 1-, 4-, and 7-m distances from high tide lines. Our methods might broadly assist bait density (and other) surveys under challenging circumstances.

Author(s): Berentsen, Are R.; Dunbar, Mike R.; Misiewicz, Regina | Abstract: Bovine tuberculosis is endemic in white-tailed deer in Michigan’s Northeastern Lower Peninsula (NELP), and evidence suggests transmission to domestic cattle. One source of transmission is through feed shared between deer and cattle as a result of deer access to stored cattle feed. Fences (2-3 m in height) have been erected to surround stored feed on at least 50 cattle farms in the NELP in order to prevent deer access. However, gate closure by landowners remains a problem. We investigated the use of polyvinyl chloride (PVC) curtains installed at gate openings as a tool to deter deer from entering stored feed areas. Deer activity was monitored through the use of infrared digital cameras and by recording deer tracks inside and outside stored feed facilities. Two treatment and two control sites were established. On the first treatment site, deer tracks inside the fenced feed area decreased post-treatment from 9 to 0. Tracks within 5 m outside the fence decreased from 28 to 13. Photographs of deer entering or exiting the gate decreased from 23 to 0. Photographs of deer near stored hay decreased from 2 to 0. No deer activity was observed on either control site or the second treatment site during the study period. While sample sizes are too small for statistical analysis, we believe the use of PVC curtains to deter deer from stored feed areas has merit and deserves additional intensive research.

Author(s): Berentsen, Are R.; Dunbar, Mike R.; Marks, David R.; Robbe-Austerman, Suelee | Abstract: Bovine tuberculosis (bTB) is a contagious disease capable of infecting wildlife, livestock, and humans. While once common in U.S. livestock, the disease has historically been rare in wildlife. However, in Michigan’s Northeastern Lower Peninsula (NELP), bTB is endemic in white-tailed deer, and evidence suggests transmission to cattle. The disease has also been documented in other wildlife species including raccoons, which frequent areas used by domestic cattle. Such interactions could facilitate transmission of bTB, but whether free-ranging raccoons shed the causative agent, Mycobacterium bovis, is unknown. We trapped raccoons on private and public land in 5 counties in the NELP from which we collected tissue samples, oral/nasal swabs, and fecal samples to determine if raccoons shed M. bovis. Culture results from 2 of 144 usable tissue sample submissions were positive for bTB, suggesting an apparent local prevalence of 1.4%, a decrease from previous estimates. Using currently available culturing techniques, swabs and feces from one tissue culture-positive animal were negative for M. bovis. While this small sample size of positive animals makes definitive conclusions difficult, we believe that although raccoons may serve as a reservoir or a spillover host for bTB, transmission risk to cattle is minimal. Further research into this arena, as well as continued refinement of culturing techniques to detect low levels of M. bovis, is warranted.

Author(s): Berentsen, Are R.; Dunbar, Mike R.; Fitzpatrick, Chadd E. | Abstract: In 2004, raccoon variant rabies moved westward from Pennsylvania into Ohio. In an effort to prevent further spread across Ohio, USDA Wildlife Services expanded the Oral Rabies Vaccination (ORV) boundary west toward Cleveland. To assist the Wildlife Services ORV Program to better understand how rabies might move through an urban area, and to help develop the best vaccination strategy to stop its spread, researchers at the USDA National Wildlife Research Center initiated a series of studies. As part of these studies, we deployed 10 remote download GPS collars on raccoons in urban areas of Cleveland. Remote download GPS collars offer advantages and disadvantages over traditional VHF telemetry and conventional “store on board” GPS collars, particularly in urban environments. Raccoons may inhabit culverts or sewer pipes that are inaccessible to humans. As a result, collars programmed to drop off may be lost and the data never recovered. Remote download capability allows researchers to retrieve data without collecting the collar. However, remote download collars tend to be larger and bulkier than other models. Out of 10 collars deployed, 1 went missing within a day of deployment, a second stopped transmitting after 5 months, and one raccoon died (this collar was recovered and later re-deployed). Data collection of nightly locations from 8 collars is ongoing. Locations are downloaded every 5 weeks. Data collected to date suggests raccoons are restricting their space use to small green-spaces when available, but also may inhabit abandoned houses. We believe this research represents the first use of remote download GPS collars on raccoons.

Author(s): Berentsen, Are R.; Dunbar, Mike R.; Fitzpatrick, Chadd E.; McLean, Robert G. | Abstract: The raccoon variant of rabies is distributed throughout the eastern and southeastern United States. Historically, the westward spread of raccoon variant rabies has been prevented by geographical barriers and the distribution of oral rabies vaccines (ORV). In 2004, raccoons positive for raccoon variant rabies were discovered beyond the vaccination zone in northeastern Ohio, suggesting the potential westward spread of the disease. To evaluate the potential westward spread of rabies across Ohio, we are employing two strategies: telemetry, and genetics. We are radio-tracking raccoons to determine which factors, if any, may be considered barriers or corridors to raccoon movement. In addition, we are collecting genetic samples from raccoons in urban and rural areas in 9 distinct regions of northeastern Ohio. These samples will be used to evaluate relatedness between raccoon populations. We hypothesize that the degree of genetic relatedness will be proportional to the distance separating populations. Populations showing less or more relatedness may be indicative of barriers or corridors to movement, respectively. Preliminary movement data suggest that raccoons are remaining within their home ranges in greenbelt areas, although some have traveled over 2.0 km into urban and suburban areas before returning. Genetic sampling is 45% complete, and analysis will be performed once all samples have been collected. The results from this study will provide a more thorough understanding of raccoon movement in northeastern Ohio. This information will allow researchers to recommend ORV bait distribution strategies to more effectively stem the westward spread of raccoon variant rabies.

Author(s): Berentsen, Are R.; Dunbar, Mike R.; Ebersole, Regina; McLean, Robert G. | Abstract: Bovine tuberculosis (bTB) is a contagious disease of livestock, wildlife, and humans. Typically, it is transmitted through inhalation of aerosolized bacilli and direct or indirect contact between animals. In northeastern Michigan, bTB is endemic in white-tailed deer, and evidence suggests deer have spread the disease to domestic cattle. Previous research indicates bTB transmission likely occurs through contamination of cattle feeding sources by infected deer and subsequent use by cattle. We are investigating deer movements in relation to farm management practices such as feeding schedules as well as locations of cattle feeding areas, hay storage sites, barns, and water sources. All locations are plotted using ArcMap software. Regular communication with cooperators allows for updates in feeding schedules and locations. We are capturing free-ranging whitetailed deer and fitting them with radio collars equipped with a global positioning system (GPS). As of 15 February 2008, we have retrieved GPS collars from 7 of 16 deer collared in 2007, and 7 new collars have been deployed since 1 January 2008. Each retrieved collar has recorded over 2,500 data points, and preliminary results suggest individual deer are staying within 1.5 km of their capture site. Spatial analysis on deer locations relative to livestock management practices and farm structures will take place when all data is retrieved in late 2008 and early 2009. Once complete, we hope this information will allow us to recommend mitigating measures for livestock producers to reduce the risk of transmission of bTB from free ranging whitetailed deer to domestic cattle.

Author(s): Berentsen, Are B.; Johnston, John J.; Mauldin, Richard E.; Schmidt, Robert H. | Abstract: The Coyote Lure Operative Device (CLOD) is a bait delivery device designed to deliver chemicals such as vaccines, sterilizing agents, predacides, and physiological markers to coyotes. Coyotes have activated the device in the field when it is filled with placebo baits, but measured delivery of an active ingredient has never been attempted. We developed a dose-response relationship for pentachlorobenzene (PeCB) residues in coyote serum and used the CLOD to deliver PeCB to captive coyotes. Twenty-two days post dosing, PeCB residues were detected in serum samples collected from every coyote that activated the CLOD. No residues were found in controls. We conclude that PeCB can be used as a physiological marker for identification of coyotes that activate CLODs. Using PeCB to quantify CLOD consumption met with moderate success and recommendations for future research are provided.

Abstract.Diphacinone and chlorophacinone, first-generation anticoagulant rodenticides, are frequently used for control of California ground squirrels (Spermophilus beecheyi) in agricultural and rangeland areas in California, USA. Owing to growing concerns over the risks to non-target species associated with the use of these rodenticides, the USA Environmental Protection Agency (EPA) proposed that the concentration of baits for above-ground use should be reduced from 0.01% to 0.005% active ingredient. We conducted field trials to compare the efficacy of 0.005% and 0.01% chlorophacinone and diphacinone baits in broadcast and spot applications for control of California ground squirrels on rangeland. We found no significant difference in efficacy owing to bait type, concentration or application method. Repeat testing is needed in other habitat types (e.g. crop areas) where alternative foods might reduce the effectiveness of a 0.005% bait application.