Current issues in wildlife damage management and the protection of human health and safety arise from the successful application of traditional methods by state and federal managers. The paradox is that these same methods are increasingly controversial. Within this constraint, management strategies may be difficult to implement. In California, for example, protecting state-threatened foxes could mean killing federally protected golden eagles. In Utah, restoring Gunnison sage grouse may require the sustained lethal suppression of predator populations unless or until habitat can be restored. The obvious fact is that these are unpopular choices, and special interest groups frequently oppose selective intervention, promoting instead somewhat neo-Romantic interpretations of ecosystem management. Luckily for the species involved, the motivating biological facts remain. The need for wildlife damage management is now a necessity in many instances, and the discipline is experiencing geometric growth. The real challenge is to make the best possible choices despite the controversies, within the already developed fabric. This presentation focuses on the contributions that USDA Wildlife Services is making to these efforts.

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.

Repellents substances and devices cause pest species to avoid otherwise attractive or palatable materials. For birds, repellents can be visual, auditory, pyrotechnic, tactile, chemosensory, physiologic, or physical. Here, we consider chemical agents only. Few substances are registered with the U.S. Environmental Protection Agency (EPA), and thus legally available for use. This lack of available bird repellent technology reflects the small demonstrable economic impact of many agricultural bird damage problems. Accurate information about damage and market size is virtually nonexistent, and private companies are reluctant to invest resources in the unknown. To successfully commercialize new repellents, clearly lucrative markets must be identified. Efforts must be made to empirically quantify damage and to estimate whether control methods are economical relative to the protection that they confer. We intend the present manuscript as a first step in these directions.

Renardine is a bone tar product available for use as a coyote (Canis 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 m2, 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.

Social, legal, biological, and political constraints dictate the need for new and improved methods of depredation management. One under-exploited approach to address these constraints may be the adaptation of methods from other damage management situations. We discuss several of these methods. Two examples are pre-baiting and diversionary feeding. The former is a standard feature of rodent control programs, but seldom if ever implemented with predators. We discuss preliminary evidence that pre-baiting increases the efficiency (and perhaps the selectivity) of some coyote management tools. Similarly, diversionary feeding is an integral component of black bear damage management for industrial timber in the Pacific Northwest. We are currently testing the hypothesis that diversionary feeding also reduces black bear depredation on livestock. Other plausible methods to reduce depredation include laser technologies, and habitat manipulation. Our efforts reflect the emphasis placed by USDA Wildlife Services and the National Wildlife Research Center on developing economically and ecologically sound strategies to manage predation on livestock, big game, and other wildlife species of concern.

Vichos non-lethal collars containing 45 to 105 ml of 3% capsicum oleo resin were evaluated as deterrents to coyote attacks on sheep. Each of five coyotes tested made neck/throat attacks on one collared lamb; four punctured collars and one pulled the collar from a lamb without puncturing it. One coyote did not resume biting the lamb for 60 min; it was retested two and four days later. At two days, the coyote punctured a second collar and briefly halted its attack. At four days, the coyote attacked a third collared lamb but made no attempt to grasp the neck/throat area. In tests resulting in collar punctures (n=5), coyotes immediately stopped their attacks and showed obvious signs of oral irritation; however, attack behavior resumed shortly thereafter (mean= 17 .6 min). Coyotes resuming attacks directed them toward the sides and rears of lambs. The Vichos collar is unlikely to prove effective in controlling coyote predation on sheep.

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.

The membership of the National Animal Damage Control Association (NADCA) was surveyed during 1995 to collect information about specialty fields, preferred methods and experience. Respondents had broad experience that included 44 species or species groups. Members reported firsthand experience with an average of 17.6 different species and 2.9 vertebrate groups. Forty-three percent indicated that their specialization was among carnivores. In this group, coyotes, Canis latrans (45%), raccoon, Procyon lotor (23%) and skunk (13%) were most frequently mentioned. Members reporting carnivore experience had firsthand experience with an average of five different species. Rural and urban members did not significantly differ in breadth of experience with carnivores. Respondents most frequently specialized with coyote (11.8%), raccoon (11.5%), beaver, Castor canadensis (9.6%) and tree squirrel, Sciurus spp. (6.8%). Trapping was the most used technique for most mammals. Exceptions were deer or elk where exclusion was preferred. Blackbirds and starlings, Sturnus vulgaris, were most often controlled by repellents or scare tactics. Removal of an animal was the most common and preferred method and represented about 70% of responses for first choice.

The continued expansion of coyote activity to new areas, the growth and expansion of human populations, undiminished difficulties faced by livestock producers in managing predation, and highly polarized public values have challenged the abilities of a new generation of scientists and students to develop effective, socially acceptable predation management methods. Work by scientists at the National Wildlife Research Center, their students, and numerous cooperators has resulted in more than 150 research papers, reports, theses, and dissertations during the past decade, substantially increasing the body of knowledge of coyote management strategies and describing progress in the development of new management methods. Much of the effort has focused on research on non-lethal techniques, methods that are selective for individual problem animals, and procedures perceived by the public to be more humane. More than two-thirds of the predator research scientists now at the Center were hired during the past decade, bringing fresh perspectives and new talent to the pervasive problems of livestock predation by coyotes.

In laboratory experiments, carbon disulfide (CS2) increases the attractiveness of feeding stations to rats and mice. Bait consumption is also increased, and the effects are more pronounced for females than for males. The present study was designed to assess whetherCS2 would enhance consumption of a standard bait formulation by wild Norway rats (Rattus norvegicus). The results showed that consumption was tripled when bait was paired with CS2. We speculate that CS2 could similarly enhance the effectiveness of rodenticide bait formulations to which it is applied. Extensive field tests of CS2 as a rodent attractant appear warranted.