A review of currently registered vertebrate pesticides is reported with by far the major weight given to strychnine and 1080. The author searched the Agency's label files and has listed most of those pesticides that have claims against at least one vertebrate animal.

Three subspecies of the California ground squirrel (Spermophilus beecheyi) were studied. In the first test of Experiment 1, Beechey (S. b. beecheyi), Douglas (S. b. douglasii), and, for comparative purposes, Sierra (S. b. sierrae) ground squirrels were each offered a drinking tube containing one of three H20 solutions of strychnine sulfate (0.01, 0.05, or 0.5%) after being deprived of water for 23 hr. In Test 2 the survivors of Test 1 were offered for 24 hr a free choice of distilled water and two of the above concentrations of strychnine solutions. In Test 3 the survivors of Test 2 were offered for 24 hr a free choice of the same three concentrations of strychnine, but plain water was available. In the three tests, lethal amounts of strychnine solutions were consumed by 11 (79%) of the Douglas, none of the 14 Beechey, and 2 (18%) of the Sierra ground squirrels. In Experiment 2 the Douglas ground squirrels again proved to be the subspecies most susceptible to strychnine when compared with Beechey. In a third experiment, the squirrels did not reject strychnine bait on the basis of odor; however, in the fourth experiment Beechey ground squirrels that had been trained to reject strychnine-treated oat groats, a preferred grain, subsequently displayed much less interest in the olfactory cues from oat groats, suggesting that both previous experiences and olfactory cues are relied upon, at least in part, in their subsequent rejection of toxic food, even though strychnine sulfate may be odorless. These data help explain some of the problems associated with the use of strychnine as a rodenticide for the Beechey ground squirrel.

Many vertebrate pesticides used by the Bureau of Biological Survey at the turn of the century were registered by the U.S. Fish and Wildlife Service (USFWS) beginning in 1960 with the U.S. Department of Agriculture (USDA). A review of archives and other documents at the Denver Wildlife Research Center (DWRC) has shown that a total of 72 federal registrations were established by the USFWS between 1960 and 1985. Because of increased regulation by the U.S. Environmental Protection Agency (EPA), selective transfers from USFWS to USDA, voluntary cancellations, conversions to state local need registrations, and a reduced development pace, there are now only 21 federal vertebrate pesticide registrations. They are maintained by the Animal and Plant Health Inspection Service (APHIS) for the Animal Damage Control (ADC) program. As a result of a 1988 Amendment to the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA 88), DWRC initiated in 1989 an extensive reregistration program for ADC's vertebrate pesticides. In the past three years, DWRC and its cooperators have submitted 188 studies in support of the reregistration of products containing strychnine, sodium cyanide, zinc phosphide, compound 1080, sodium nitrate, carbon, DRC-1339, and PA-14. Since 1989, the reregistration of these 8 active ingredients has taken priority over the development of new vertebrate pesticides at DWRC in order to concentrate on gathering data for these chemicals of the past. New tools to mitigate human and wildlife conflicts must continue to be the goal of present and future federal research.

The Environmental Protection Agency's (EPA) reregistration process has had an extensive impact on the Animal Damage Control Program administered by the Animal and Plant Health Inspection Service (APHIS) of USDA. Specifically, the 1988 Amendment to the Federal Insecticide, Fungicide, and Rodenticide Act required a comprehensive reevaluation of pesticide safety; nearly 500 data submissions have been requested by EPA from APHIS to maintain its federal (Section 3) and state (Section 24(c)) low volume minor use vertebrate pesticide registrations. These registrations are used to control damage to American agricultural resources, mitigate losses to selected wildlife species, and reduce threats to public health and safety. A primary function of both APHIS's Denver Wildlife Research Center (DWRC) and Technical and Scientific Services (TSS) office is the maintenance of these registrations containing carbon, sodium nitrate, Compound 1080, sodium cyanide, DRC-1339, PA-14, zinc phosphide, and/or strychnine. APHIS has responded to EPA's data requests in a variety of ways including: requesting waivers, negotiating data requirements, proposing less costly alternatives, monitoring data contracts, and conducting the necessary studies. Since 1989, DWRC and its cooperators have submitted over 250 studies in support of these registrations. This paper will: 1) discuss the active ingredients in APHIS's vertebrate pesticides and their reregistration status; 2) evaluate the effectiveness and cost of each type of response; and 3) provide lessons for the future.