National Wildlife Research Center (NWRC)

Project Accomplishments 2008

Trap Devices Tested For Capturing Canids—Due to a growing international concern for animal welfare and the need to capture and handle specific species for conservation, management, or recreational purposes, there is an increasing need for scientific evaluation of capture methods.  Scientists at the NWRC field station in Millville, Utah, evaluated the efficiency and selectivity of cable restraint devices and cage-traps for the capture of red foxes and the incidence of injury to captured animals at four sites in Castilla y León (Spain) during spring 2006.  All traps performed similarly at all sites, with no apparent site and trap interactions.  Fox capture rates and mechanical efficiencies of the Belisle (Edouard Belisle, Saint Veronique, Québec, Canada) and Collarum (Wildlife Control Supplies, East Granby Connecticut, United States) were similar, but both had higher capture rates than the cage-trap.  Similar to previous studies, the Collarum was 100% selective for canids and had a selectivity of over 94% overall, which was higher than that for the Belisle (63%); both Collarum and Belisle were much more selective than the cage-trap (21%).  Fox injuries were statistically indistinguishable using injury scores, but the Collarum and the Belisle surpassed international standards for humane trapping; the number of animals captured in cage-traps was insufficient to allow for evaluation.  While both the Collarum and the Belisle may be useful for capturing foxes in Spain, training and experience with each may be necessary to ensure the highest efficiency while still preventing injuries, especially to non-target species.

Using Aversive Conditioning to Repel Bears—NWRC scientists are investigating whether taste-aversion conditioning is effective at reducing black bear visits to food sources.  Taste-aversion conditioning occurs when the taste and/or smell of a flavor is associated with severe gastro-intestinal malaise, such that an animal subsequently rejects or avoids that food.  Conditioning occurs most effectively when a novel flavor is used.  In recent years, conflicts with bears and human-bear encounters have amplified, jeopardizing both human and bear safety, especially where human food sources are available (e.g., in campgrounds).  This increase in nuisance activity has prompted a need for wildlife managers to explore and implement successful predator conflict management techniques.  Many varied management techniques, both lethal and nonlethal, have been used to reduce human-wildlife conflicts.  While methods using both approaches have been successful at reducing some conflicts, there has been a growing interest from wildlife managers and the public in using less-invasive, nonlethal means of wildlife and predator management. 

However, since the nature of wildlife conflicts is diverse, and many nonlethal management tools are limited in their capacity to reduce conflict, it is important to develop a variety of techniques to mitigate these problems.  Taste-aversion conditioning is one potential alternative.  NWRC scientists are conducting  research to determine the effectiveness of thiabendazole for establishing a taste-aversion to a flavor and to test the effectiveness of this method at reducing or preventing bear visits to food sources.  Thiabendazole is particularly promising because, unlike other chemical aversive agents used in the past, this compound is believed to be relatively tasteless and odorless, allowing for animals to form an aversion to the flavor of the food consumed and not to the chemical itself. 

At the end of 2007, NWRC completed the first round of experiments with captive and free-ranging black bears to examine the effectiveness of conditioned taste aversion (CTA) for reducing food consumption and visitation at campgrounds and other food sources.  NWRC researchers tested captive black bears by offering them food (donuts) treated with 10 g of thiabendazole (TBZ) and a novel flavor (peppermint) on three different occasions; bears fully consumed treated bait each time, and CTA was never established.  Subsequently, the researchers conducted a field experiment in the La Sal Mountains, Utah.  They established and constructed 26 simulated campground sites using plastic trash bins containing 300 g of baked goods (cakes, donuts).  After four weeks, they treated 50% of the sites with 10 g of TBZ and a novel flavor (camphor).  While bear visits to the simulated campgrounds were not reduced using TBZ, food consumption appeared to be reduced at some sites.  NWRC is continuing additional studies of free-ranging bears in FY 2009 that will help determine why previous tests of flavor avoidance conditioning with TBZ had limited success.

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Logan, UT, Field Station