VPC Shows Its Backbone

By: Dale E. Kaukeinen

Industry experts gather in San Diego for the 23rd Vertebrate Pest Conference to share the latest on wildlife issues, disease studies and removal & elimination techniques.

The 23rd Vertebrate Pest Conference (VPC) was held March 17-20 at the Westin Emerald Plaza in San Diego. This conference has been held every two years since 1962, and typically alternates among various West Coast locations. This year’s event attracted 273, representing 39 states, the United Kingdom, New Zealand, Australia, Israel and Canada.

Participants included staff from the National Wildlife Research Center of the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service (USDA-APHIS NWRC) in Ft. Collins, Colo., and various field locations of the USDA/APHIS Wildlife Services. The University of California and its extension service were represented, as was vector control staff from various governmental agencies. In addition, many individual pest management and wildlife management companies were also represented.

Structural strategies: Much of the conference dealt with wildlife issues in urban and suburban areas, disease studies (rabies, hantavirus, bacterial contamination of vegetable crops, etc.) and removal or elimination techniques. The western flavor of the conference appeared in the many papers about prairie dog management and control, ground squirrel issues, and coyote and mountain lion studies.

Gopher control: Devices developed to control gophers and ground squirrels by exploding their burrows were applied to woodchuck control by Rick Shadel of S&S Wildlife Control of Harrisburg, Pa. A device mixing propane and oxygen is introduced into burrows and exploded remotely. Excavations revealed the technique is particularly effective in eliminating any woodchucks, as well as collapsing much of the burrow system.

Commensal rodent research: A few presentations dealt with commensal rodents and their role as economic pests and disease vectors. Some had potential application to developing new methods of control. Dr. Gary Beauchamp of the Monell Chemical Senses Center of Philadelphia, for example, presented interesting work on how an increasing understanding of taste receptors might better allow the development of species-selective attractants and repellents.

Birth control: Use of contraceptive materials were described for reducing populations of various pest animals, including rabbits, and native rodents such as ground squirrels and prairie dogs in environments where killing may be unpopular or where a small population is desirable. Tests with prairie dogs, for example, indicated the best approach was to remove at least half of the population, and then to apply contraceptives every five years to sterilize younger animals. Because of the rapid breeding in rabbits, more than 80 percent sterility in females needs to be achieved in the field to reduce populations. A similar level would probably need to be reached for other rodent pest species, such as rats.

Because many contraceptives being studied are not species-specific, there would need to be targeted delivery systems to prevent accidental sterilization of non-target animals. An approach with larger rodents, such as squirrels, was described involving a feed hopper with a weighted lid that smaller animals would not be able to lift to feed.

A contraceptive vaccine was tested on Norway rats that created antibodies interfering with the rats’ production of sex hormones, eggs and sperm. It was judged to not be a realistic replacement for conventional extermination techniques. Contraceptive agents act very slowly to reduce populations, and sterile animals can still cause damage and spread disease.

A further problem being realized with birth control for wildlife pests is that sterile females live much longer than normal because they are not tasked with the biological demands of breeding, pregnancy, nursing and defense of the young. Contraceptives will probably find the most use with larger, long-lived animals where extermination is not desired, such as to combat deer problems in urban and suburban environments.

Remote trap monitors: A report on remote trap monitors described telemetry equipment that will signal when traps are sprung. Used mainly in remote areas to reduce the effort to check cage traps when going after large predators, the technique is still too expensive for routine use with multiple traps set for small rodents. However, it suggests that in the future, as costs come down, trap captures — or even bait station visits — could be relayed to you on your cell phone for an immediate response.

Anticoagulant update: The paper I presented attempted to summarize the background of the U.S. Environmental Protection Agency’s (EPA’s) concern — and that of other governmental and some environmental groups — over the impact of single-feed and other anticoagulants to non-targets, principally the risk to children and to wildlife. Pending EPA decisions could greatly change how the second-generation, single-feed anticoagulant rodenticides are used, and may possibly lead to them being restricted to professional use only. Increased use of bait station placements by consumers, and more use of block baits that can be secured in such stations, is likely.

Municipal planning: A presentation by Dr. Bruce Colvin, a small-mammal ecologist and rodent expert, outlined the approach necessary to set up effective municipal rodent control programs, including what organizational structure and programs are most effective. He based his recommendations upon his work in Washington, Boston and elsewhere. Use of an “Environmental Management System” was proposed to encompass, track and monitor all aspects of control programs.

See you in Sacramento

Overall, experts from a variety of areas gave a total of 66 presentations, which will appear in expanded form in the proceedings volume that is slated to be available by October 2008. You can browse contents of prior proceedings at the University of Nebraska’s Digital Commons: http:// digitalcommons.unl.edu/vpccollection.

For copies of the 23rd VPC proceedings and back issues, contact the University of Nebraska’s store: http://nebraskamaps.unl.edu.

The 24th VPC will be held in February 2010 in Sacramento, Calif.

You can reach Kaukeinen, an industry veteran with more than 30 years of experience, at 302-521-4637, or e-maildkaukeinen@comcast.net