We investigated the hypothesis that the squirting of blood from orbital sinuses by Texas horned lizards (Phrynosoma cornutum) is an antipredator defense against some mammalian species. Coyotes (Canis latrans) were tested for the first time. As expected, Texas horned lizards squirted blood in response to coyote attacks, and coyotes exhibited startle response, avoidance response, or both as a result of these events. Whereas lizard carcasses mixed into normal foodmash elicited regurgitation by coyotes, possibly due to physical effects, blood of horned lizards similarly mixed into food did not. Coyote responses to simulated squirts of 5 compounds, including blood of horned lizards, into 3 potential sensory target areas (eyes, nose, and mouth) strongly suggested that aversive effects were mediated by receptors in the oral or nasal cavities. Coyote responses were more frequent to delivery of blood plasma and whole blood of Phrynosoma to buccal and nasal membranes than to delivery of plasma and blood from spiny lizards (Sceloporus jarrovii) or to delivery of a saline control to these membranes. We concluded that Texas horned lizards squirt blood from sinuses surrounding the eyes during attacks by canids, such as coyotes, and that this blood affects oral receptors, causing a negative response in coyote attack behavior that potentially increases survival of the lizards.

Author(s): Houben, John M.; Mason, J. Russell | Abstract: We recorded the weight and age of 70 coyotes collected during depredation control efforts in western Virginia. Mean masses for adult male and female coyotes were 16.2 and 13.4 kg, respectively. Juvenile male and female coyotes weighed 14.0 and 13.0 kg, respectively. Regardless of sex, mean mass was greatest between November and January and comparable to that reported for coyotes throughout the eastern United States. Cementum aging indicated that 71% of the coyotes captured were greater than 1 year of age. Numerical trends suggest that age and sex may influence vulnerability to capture.

Aerial hunting is an effective tool for the removal of problem coyotes (Canis latrans). However, factors that predict hunt success remain largely obscure. To address this issue, we asked USDA-APHIS-Wildlife Services pilots in five western states to record meteorological data, ground conditions, and flight circumstances (e.g., purpose of flight, whether or not a ground crew was used) between December 1998 and August 1999. We obtained 426 flight records and evaluated them in relation to coyotes seen/h and coyotes killed/h of aerial hunting, with pilot as a covariate. Air temperature, resource to be protected, use of ground crew, degree of preventative control, cloud cover, snow cover, vegetative cover, wind direction, season, and lunar phase were significantly (p⩽0.05) related to coyotes killed/h of aerial hunting. Variables that were not significantly (p⩾0.05) related to coyotes killed/h were wind speed, steepness of terrain, barometric pressure and shotgun cartridge type. Our findings may have practical implications for increasing the efficiency of both aerial survey and aerial hunting operations important for coyote damage management.

Coyote attractants are inherently variable because they are usually derived by mixing and fermenting complex biologically derived substances. We designed the present study to address this problem. We collected volatiles by purge and trap headspace analyses from 33 commercially available attractants, and analyzed the trapped odors by gas chromatography with mass selective detection. We then statistically evaluated chromatographic peak area data to produce recipes for seven new chemical attractants. We presented these attractants to coyotes in one-choice tests at the Predation Ecology and Behavioral Applications Field Station of the USDA-APHIS-WS National Wildlife Research Center near Logan, Utah. Our results indicated that there were both seasonal and sexual differences in stimulus attractiveness. We also found that several attractants were more effective than Fatty Acid Scent (FAS), a commonly employed coyote attractant. A field trial to evaluate the effectiveness of new candidate attractants is planned.

The identification of new chemical repellents for wildlife damage management is impeded by the need to perform cumbersome and expensive behavioral tests. Here, we report the development of in vitro cell culture methods to increase the speed and efficiency of repellent screening while reducing costs, as well as the number of animals necessary for research. Our methods exploit the fact that effective primary repellents depend on the stimulation of pain receptors. We cultured trigeminal nociceptors (pain receptors) from Norway rat (Rattus norvegicus, laboratory strain), white leghorn chicken (Gallus gallus), coyote (Canis latrans), white-tailed deer (Odocoileus virginianus) and Canada goose (Branta canadensis), and then applied digital fluorescence microscopy to measure changes in intracellular calcium (an index of cellular activation) in response to applications of known and effective repellents. Capsaicin, bradykinin and acetylcholine were more effective stimuli for rat, coyote, and deer neurons than cells from chicken.

Renardine(1) is a bone tar product available for use as a coyote (Cants latrans) repellent in Canada. The substance is applied to pasture borders to prevent coyotes from entering and attacking sheep. Because data regarding the effectiveness of Renardine are lacking, we designed two experiments. In the first, six pairs of coyotes were first presented with 400 g of ground meat in two pans (200 g/pan) with false screen bottoms. Beneath the screens were absorbent tubes wetted with 10 ml of distilled water. Subsequently, during a treatment period, the absorbent tube was wetted with 10 ml of Renardine. Pans were presented for 60 minutes, and the amount of time to consume the meat was recorded. In the second experiment, six additional pairs of coyotes were first presented with 200 g of ground meat inside a barrier created with baling twine and wooden dowels. The area inside the barrier was 1 m(2), and the twine was tied onto the dowels 0.25 m above the ground. During the treatment period, the twine and dowels were painted with Renardine. In both experiments, all coyote pairs consumed all of the ground meat shortly after presentation. We conclude that Renardine probably is not an effective coyote repellent. However, because the active ingredient in Renardine is bone tar oil and bone tar oil is deer repellent, we speculate that Renardine may have utility as an herbivore repellent.

We describe a portable apparatus designed to examine the free-operant food preferences of captive coyotes in their home kennels. Because lever-pressing for food access was the dependent variable, we measured food preference independently of food ingestion. Using successive approximation, we trained 8 out of 19 coyotes (42%) to use the apparatus. This percentage is similar to training rates for dogs. We used fixed and variable ratio schedules of reinforcement to further test 4 of the trained coyotes. All 4 produced response curves similar to those of other species on similar schedules of reinforcement.

Available evidence indicates that effective coyote attractants are blends of volatile substances. Typically, attractants are a combination of biological substances such as fermented glandular materials, urines, and rotted meats. Although effective, these attractants have several distinct disadvantages. Among these is the possibility that they are unnecessarily complex and variable and, thus, difficult to replicate from one batch to the next. Although attractants containing a few reagent grade materials are available, the chemicals selected and their concentrations are not derived from actual attractants. For this reason, commercially available coyote attractants were analyzed with the intention of developing relatively simple synthetic alternatives. Purge and trap headspace analysis with gas chromatography/mass selective detection was employed to identify the volatile components of known conventional and synthetic attractants. All identified compounds were grouped according to chemical functionality, and one compound from each functional group was chosen to represent the group. Using only these representative compounds, seven synthetic attractants were formulated. Bioassays with captive coyotes (Canis latrans) were conducted to compare behavioral responses elicited by the seven new attractants, a currently available synthetic attractant, and a control. The results indicated that the attractants elicited significantly different behavioral profiles.

Deer Away Big Game Repellent(R) (BGR) effectively deters browsing deer, most likely by the release of sulfur odors and volatile fatty acids. Because many herbivores avoid these odors, a logical inference is that BGR may repel herbivores other than deer. To address this possibility, we tested whether BGR was repellent to eastern cottontail rabbits (Sylvilagus floridanus). During fall-winter of 1994-95, we located 4 test sites (0.4- 2.0 ha) in commercial nurseries in southern New Jersey. Different sites were planted to flowering pear (Pyrus calleryana), dogwood (Cornus florida), firebush (Pyracantha coccinea), and crab apple (Malus spp.). We split each site into 2 plots (0.2-1.0 ha), and plots then were randomly assigned to the treatment or control condition. After recording the number of damaged plants in each plot, we applied a 32.4% (mass/volume) solution of BGR to treated plots at the labeled rate of 3.8 L/400 plants. We applied water alone to plants in control plots. During a el-day posttreatment period, we reassessed damage at 7-day intervals. During fall-winter of 1995-96, we repeated treatment and control applications, except that conditions were reversed (i.e., former control plots were treated with BGR and vice versa). We estimated rabbit numbers at each site during both years of the study and chemically evaluated the environmental persistence of BGR during the first year. Big Game Repellent was an effective repellent at all sites during both years of the study. These findings are consistent with the possibility that BGR represents an omnibus repellent for problem herbivores.

Author(s): Mason, J. Russell | Abstract: Repellents include chemical substances, visual displays, and sonic and ultrasonic deterrent systems. The use of electric shock also can be considered as a repellent category. Each of these categories is discussed, together with their respective utilities, constraints on their usefulness, and possibilities for future development. Economic considerations that may impede or expedite the development of new strategies are presented. Repellent effectiveness depends upon a complex of variables, including the palatability of protected and alternative foods, weather conditions, and the number of animals causing problems. Invariably, repellents are most useful when used as components of integrated pest management strategies.

No-till agriculture involves the use of pelleted and granular pesticides and chemically treated seeds. Some of these products kill birds. The present experiments were designed to investigate whether four candidate repellents (methyl anthranilate, ortho-aminoacetophenone, d-pulegone, and pine oil) would reduce consumption by European starlings (Sturnus vulgaris) of clay particles similar in size and shape to particles normally used for pesticide delivery. All substances reduced consumption (P < 0.05), although none completely eliminated it. To achieve further reductions in consumption, other particle characteristics might be considered. These include the use of colors that make particles indistinct from the substrate, and a texture or particle size that diminishes the likelihood that particles will be ingested as grit.

Fertility control in wildlife is emerging as a potential management tool. Published research on feral horses, deer, rodents, and rabbits suggest an effective agent producing reversible infertility in these species could be developed. Furthermore, anecdotal reports suggest that infertility can be induced in a greater array of species. In this paper, the authors review methods of fertility control being studied for application in wildlife and focus on their studies designed to evaluate the effectiveness of fertility control agents in coyotes (Canis latrans). Immunocontraception using porcine zona pellucida (PZP) is currently the most promising method of fertility control in coyotes the authors have studied. This is consistent with results from other species. However, the vital question of whether any fertility control agent can reduce livestock losses due to coyote predation will require more research.

In reforested areas, underground strychnine baiting to control pocket gophers (Thomomys mazama) poses a hazard to golden mantled ground squirrels (Spermophilus lateralis) and yellow pine chipmunks (Eutamias amoenus). We designed this study to assess whether: 1) chemical insensitivity to bitter tastes might explain the ingestion of strychnine; 2) pocket gophers would avoid four bitter-tasting compounds: quebracho (QUEB), sucrose octaacetate (SOA), quinine hydrochloride (QHCl), and denatonium benzoate (DB); and 3) nontarget species could be trained to avoid strychnine paired with the most aversive compound. Our results showed that while all species readily consumed strychnine, the nontarget species could be conditioned to avoid it. Moreover, while high (0.1%) concentrations of DB, quinine hydrochloride, and quebracho reduced consumption by pocket gophers, 0.05% DB was inoffensive. Nontarget animals readily avoided 0.05% DB, and avoidance was stronger after conditioning. Together, our results suggest that all of the rodents tested are insensitive to strychnine, high concentrations of some bitter tastes may be effective pocket gopher repellents, and lower concentrations of DB may selectively repel nontarget animals from strychnine baits.

Garlic and garlic oil were recently exempted from pesticide registration requirements, increasing the attractiveness of these substances as candidate vertebrate repellents. Because anecdotal evidence suggests that garlic may repel birds, the present experiment was designed to evaluate the aversiveness of garlic to European starlings (Sturnus vulgaris). Samples of feed were mixed with garlic oil to produce concentrations ranging from 1.0-0.1% (vol./mass). All garlic concentrations reduced consumption relative to consumption of untreated feed in two-cup choice tests (P < 0.05). These results are consistent with the possibility that garlic oil may be used to repel these birds.

Siberian pine needle oil, a mixture of potentially repellent compounds, deters feeding in herbivores. To determine its effectiveness as a general vertebrate repellent, we compared the feeding responses of 2 rodent and an avian species to olfactory and oral cues of Siberian pine needle oil. In 2-choice tests, subjects had access to 2 apple pieces, 1 coated with the vehicle solution (vegetable oil) and the other with the repellent solution (Siberian pine needle oil). Deer mice (Peromyscus maniculatus) ingested 1.9 ? 0.1 g of oil-coated apple compared to 0.7 ? 0.1 g of apple adulterated with 10% pine needle oil (P < 0.05). Prairie voles (Microtus ochrogaster) ingested 2.4 ? 0.3 g of oil-coated apple compared to 1.5 ? 0.2 g of apple treated with 10% pine needle oil (P < 0.05). In contrast, European starlings (Sturnus vulgaris) were insensitive to pine needle oil's aversive effect. Prairie voles increased their avoidance of pine needle oil-adulterated apple in 2-choice tests following repeated exposure to the stimuli. However, in 1-choice tests neither oral contact with pine needle oil nor exposure to its volatile cues decreased apple ingestion by prairie voles. Siberian pine needle oil has promise as a rodent control agent when employed in settings where use of a nonlethal product is desirable and alternative food sources are readily available. J. WILDL. MANAGE. 61(1):235-241