Baiting with Terad₃ in Death Valley National Park

Death Valley National Park, three million acres of wilderness along the California/Nevada border, is a land of extremes - from Badwater Basin, the lowest point in North America at 282 feet below sea level to the 11,000-foot snow-capped Panamint Mountains.

This stunning landscape offers its million-plus annual visitors a glimpse of exotic desert wildlife - birds, mammals, plants that have adapted to the park's harsh conditions where summer temperatures top more than 120° F.
Like many tourist destinations, the park also has its share of less desirable Norway rats, house mice and deer mice which William Morris, operations manager of Pestmaster Services, Inc. in Bishop, Calif., discovered last year.

"We were servicing the park for an insect problem and noticed rodent activity," Morris recalled. "They had rodents everywhere and weren't doing anything to curtail it."

"Not your everyday account"
At the time, Morris suggested setting up control measures, but it was several months before park management called him back to explore the idea. He soon realized that implementing a rodent control program in a national park was "not your everyday account."

"It was a slow process. Everything had to go through appropriate channels," he said. "And with historical sites, you can't do anything to degrade the buildings."

The park's popular Scotty's Castle, a 1920's Spanish-style mansion, for example, had numerous rat burrows around its perimeter that would require special care.

"Initially, the park wanted to use live traps. I had to explain that, with mice, the gestation period is short and populations grow so quickly that live trapping wouldn't be successful," Morris recalled.

"They didn't want to use glue boards. I told them a baiting program is the only way to get populations down to a controllable level, an acceptable level."

Park's first rodent baiting program
After deliberation, the park management agreed to a pre-baiting assessment program before moving into a full-fledged baiting operation. According to Morris, although national parks have an IPM plan, Death Valley is the first one to implement a rodent control baiting program.

Personally undertaking the job, Morris and his technicians last November set up an external pre-baiting program using 70 donated PROTECTA LP Bait Stations baited with Bell's non-toxic DETEX BLOX.

Over the next several weeks, they checked bait stations frequently to pinpoint the main sources of the infestation. They assessed the number of hits in bait stations from different areas and recorded the results. The park monitored results, as well.

In December prior to baiting, Morris held a training seminar on-site to educate park staff on the baiting methods he would use. Then, for the next several months, traveling the 120 miles between the park and their offices, Morris and his technicians baited and monitored the stations.

Baiting with low-risk Terad₃
At the recommendation of Bell representative, Jeremy Davis, Morris baited with Terad₃, Bell's Vitamin D₃ rodenticide that reduces the risk of secondary poisoning and poses lower toxicity to birds. 

"We had to be careful of other wildlife so we chose Terad₃ for its low risk," Morris explained. "Terad₃ was great. It was the first time I used the product and we had good acceptance. It did pretty good out there both to reduce the population and its impact in regard to structures."

Technicians moved bait stations when bait was no longer taken and added stations in areas of high activity. They also worked with park staff on exclusion measures.

"This is an historical site and exclusion is the main key to prevention," Morris pointed out.

Many of the non-tourist historical buildings were overrun with deer mice which meant Hantavirus clean-up. Using respirators, hepa-filtered vacuums, and sanitizers, technicians carefully treated the site, one building at a time.

60-70 percent drop in populations
All in all, Morris' patience and deliberate work paid off. 

"I told the park staff that baiting would reduce populations by 50 percent in the first three months and I did that. Between December and March, we reduced the population by 60 to 70 percent," he said.

Once baiting was completed, they pulled the stations and the park now uses live traps to monitor for rodents.
On a long-term basis, however, the park agreed to a cyclical rodent control program with two weeks of pre-baiting and one month of baiting, followed by three months of monitoring.

 "Initially there was quite a bit of opposition to ‘industry thinking' but now I've gathered some support," Morris said. He is also working with the staff on the park's own IPM plan.

 "A lot of people don't understand IPM, bringing the population down to a controllable level for health, safety and environmental protection," Morris added. "But we're gaining support."