Retrofitting Rodent Bait Stations

Someone once said that "Necessity is the mother of all invention." Adam Warrix, commercial pest management specialist for Columbus, Ohio-based Varment Guard Environmental Services, knows this all too well.

THE CHALLENGE. Warrix was servicing a new exhibit at a zoological park. The building is a 25-foot-tall concrete block construction. The block walls rest on a concrete footer which defines the poured concrete floor. Natural sunlight enters via large skylights. Inside, a tropical rain forest theme is accented with artificial rock outcroppings made from sculptured concrete. Multiple species of birds — some very rare — are on display, where they walk and fly about freely throughout the exhibit. The climate in this setting is very damp and warm. Despite the fact that there were no noticeable points of entry for mice, several deer mice had been found in the building.

The staff veterinarian was adamant that no rodenticides were to be used in or around the building. She was fearful that dead mice would pose a secondary toxicity threat to the birds. We naturally agreed.

ANOTHER OPTION NEEDED. To reduce the rodent population on the outside, Warrix wanted to place exterior bait stations around the perimeter. Unfortunately, that was unacceptable to the veterinarian, which left us scratching our heads.

Due to environmental integrity issues and unwanted visibility to patrons, multiple catch and mechanical traps were not a practical fit. We suspected that the rodent pressure in and around the building could be managed adequately with snap traps, if they were placed strategically.

TRIAL AND ERROR. We pondered how snap traps could best be deployed for this situation. Should we hide them in cardboard boxes? Should we put them under trash cans, or make habitat "blinds" to mask the snap traps?

While Warrix and I sat at the conference tables at the office, we played with the old-fashioned (and very useful) wooden snap traps, tinkering with ways to position them in the Syngenta Multiplex Station to enable a quick and easy capture, detection and re-set mechanism. After a couple weeks of service at the account, we noticed that the snap traps were being tripped accidentally during station inspections.

Warrix and I went back to the drawing board. We grabbed some Kness SNAP-E traps. We started by attaching a small pan head screw through the bait cup of the SNAP-E trap and into a hole for a bait rod. It fit perfectly. We proceeded to secure two snap traps in each station.

We still faced the dilemma of setting the trap and closing the lid without setting off the trap. I remembered a test by Dr. Richard Kramer using marking flags as a way to bait rat burrows. We took a couple of lawn flags and drilled two small holes in the lid of the station. We bent the rods around the trap-setting mechanisms and pulled. It worked great.

We shortened the rods so that the flags stood up when the traps were set. If the flags were down against the lid then we knew the traps had been tripped. We thought we had a perfect system until someone mentioned, "Who wants stations around their facility that have little flags sticking out of them?" They were right.

Even though they were functional, the flags were ugly. It was back to the drawing board. We had just completed a bird wire installation service and had scrap wire lying around. The crimps made attaching easy.

Warrix discovered that drilling holes in the back of the station prevented water from collecting inside. The second prototype station was ready for testing. A small loop, like that on the end of a yo-yo string, was made in the cable on the exterior side of the station (see photo on page 30). This would serve two purposes. The first was to set the trap with a simple tug on the cable loop. The second was to provide a way of checking the station without opening the lid. If the loop was close to the station then the traps were tripped. If the loop was a couple of inches away from the station, then the traps were still set.

CONCLUSION. The results of the test were rewarding. We were able to identify that the vertebrate pest pressure was attributed to not only deer mice but also to voles and shrews. This gave us information about the habitat around the facility and enabled us to control voles and shrews in the brush areas. But the most satisfying result was the feeling of accomplishment that we shared when the staff veterinarian saw our digital images of successfully captured rodents and shrews (see photos above). Her acceptance meant that we met her needs, the zoological park’s needs, and the goals we aspired to as commercial pest management specialists.

Dave Ramsey is operations manager, ProGuard Division, and Adam Warrix is commercial pest management specialist, both of Varment Guard Environmental Services, Columbus, Ohio.