Plant extracts, animal glandular secretions and excretions, and natural food flavoring agents are common sources of natural products that can be used in animal damage control applications. Such products can be used either by themselves (e.g., coyote urine as a rodent repellent), or in combination with other control agents (e.g., food odor or flavor enhancer at baiting sites). The Environmental Protection Agency registration requirements are described for a variety of potential applications of natural products including bird and rodent repellents. In some applications, the product chemistry or other data requirements could make the registration process prohibitive due to the cost of chemical identification and quantification of compounds. Under a new Reduced Risk Pesticide Program, however, many data requirements for registration of natural products can be waived by EPA with the exception of some toxicology and efficacy studies.

To evaluate the potential of using nesting material as a medium for avicide delivery, five organophosphates (Dasanit®, Volaton®, fenthion, parathion, and Cyanophos®) were tested on small groups of paired male-female quelea (n = 4 to 9). Toxicants were presented to each pair of birds on five 13-cm strands of cotton string after a preliminary screening for male nest weaving behavior. Tested concentrations ranged from 100% technical grade to 0.003% compound diluted with acetone. Dasanit® was found to be the most effective candidate with some lethal effects noted at 0.012%. An optimal concentration for Dasanit® was estimated to be 0.80% based on combined male and female mortality (72%). This level was further evaluated in two aviary cage tests using 25 male-female quelea pairs during three-day exposure periods. A first replication yielded mortality ratios of 23:25 (92%) for males, but mortality ratios of only 1:24 (4%) for females. The second replication yielded mortality ratios of 24:25 (96%) for males and 11:25 (44%) for females. Females in the second group showed more weaving attempts than those in the first replication group, which could explain the pronounced mortality difference. Safety concerns about the use of toxicant-laden nesting material have not yet been evaluated in Africa. These concerns need to be addressed relative to the knowledge and literacy level of the local people applying the materials and to their awareness of methods of limiting pesticide exposures to the general public.

A two-choice, taste preference study was conducted using 18 northern pocket gophers to evaluate pelleted sorghum, granulated sorghum, and wax block baits containing either 0.01 to 0.05% quinine or 0.10 to 5.0% sucrose. Bait consumption was significantly higher across treatments (P ≤ .001) for granulated sorghum, followed by pelleted sorghum, and wax blocks. Gophers also showed a high frequency of moving the granulated bait in their cheek pouches to be deposited at alternate locations within their cages. Although increasing sucrose concentration did not produce significantly (P ≥ .10) enhanced consumption for any of the baits, a trend toward increasing preference with increased concentration was noted for the wax block bait. During quinine tests, bait consumption was again significantly highest (P ≤ .01) for granulated sorghum followed by pelleted sorghum and wax block. Quinine treatment also failed to significantly (P ≥ .10) alter bait consumption across the tested concentrations. However, there was a minor trend toward decreasing preference with increasing concentrations in the wax block group. Data indicated that pelleted bait had the advantage of producing more consistent consumption levels without the animals carrying bait in their cheek pouches for caching and subsequent spillage. Although the wax block baits were most influenced by the taste treatments, consumption levels were extremely low. In comparison with most wild rodent species, northern pocket gophers were found to be insensitive or indifferent to both taste stimuli over a wide concentration range.

Controlled laboratory and field test protocols were developed to assess the repellent efficacies of six commercially manufactured ultrasonic rodent repellent devices. The laboratory test structure (68.7 sq m) was divided into two rooms (32.5 sq m each) with a central harborage area (3.5 sq m) containing a colony of 12 wild Norway rats (Rattus norvegicus). For each test, a single ultrasonic device was attached to the far end of one room and rat activity measures (oat consumption, packet damage, photocell counts) were taken during 1-week baseline and 2-1/2-week test periods. Field test structures varied in floor area (6.5 to 197 sq m) and were of either metal or wood construction. All contained existing Norway rat, house mouse (Mus musculus), or field mouse (Peromyscus maniculatus) infestations. No rodent control was conducted at these sites other than the application of selected ultrasonic devices. Rodent activity (packet damage, food consumption, rodent tracks) was measured twice per week during three successive 3-week intervals with devices operating only during the second interval. Repeated measures analysis of variance and chi square were used to statistically evaluate the reliability of ultrasound effects.

Four individually penned coyotes (Canis latrans) that had learned to kill live domestic rabbits for food were presented with one black and one white rabbit during daily 1-hour sessions and punished by a brief, severe shock from a high-voltage collar each time they attacked the black rabbit. One coyote did not learn the color association; after three shocks, it refused to kill either rabbit for 10 days but killed both indiscriminately when retested 4 weeks later. The other three coyotes learned to avoid black rabbits after only three to five shocks and, when repeatedly retested without shock at several-week intervals, did not begin killing them again until 3 to 9 months later. These animals' rapid acquisition and long retention of an avoidance response to a certain class of prey suggests a potential for aversive stimuli to reduce coyote attacks on livestock.

Taste enhancers and olfactory attractants are needed to improve bait acceptance for rodent control, but most methods for evaluating preference for taste and odor stimuli are not suitable for screening large numbers of such compounds. This paper describes two automated preference testers designed for this purpose. The taste preference apparatus is based on the principle of the brief-exposure, foods-together technique, whereby the animal briefly samples each food alone, in alternate sequence, before the two foods are presented together, in alternate positions. The odor preference tester is based on an open-field maze, whereby the test animal samples each of four odor sources before preference behavior is recorded. Both devices are fully automated (in both operation and data recording), are free of position bias, and produce preference determinations in relatively little time; neither requires special training of test animals. The design, operation, and application of each apparatus in rodent control is discussed and illustrated.