Anti-Pest Campaign Intensifies At Zoo

Traps, Bait Boxes Set to Stop Rats

The National Zoo has launched a new attack on the rats and mice that have long menaced the animal park, stepping up efforts to trap and poison the rodents and plugging holes in buildings where they have had easy access to many indoor exhibits.

The assaults on rodents have included placing snap traps near zoo dumpsters and animal areas that attract rats, setting out more than 80 bait boxes around the park and flooding some rat holes.

Feeding stations have been elevated above exhibit floors, where feasible. Wire-mesh ceilings on some enclosures have been reinforced with coverings with holes small enough to keep mice out. Gaps under entryways have been filled with door strips, and many birds now eat from bowls placed on stands in their ponds.

"It's a work in progress to decrease the rodent population, not an overnight change," said Suzy Alberts, the zoo's pest management specialist. "We still have pockets [of infestation], but it's much better."

Some rodents die in traps, while others eat poisoned bait and die elsewhere, so Alberts can't estimate the number of rodents killed. Citing one example, the zoo said that in January it trapped 26 mice in one night in the saki monkey and tamandua anteater exhibit, which is now free of rodents.

Like other animal parks, the 163-acre National Zoo, which is part of the Smithsonian Institution, constantly battles rodents and insects. But its marauding rats have killed prairie dogs and traipsed brazenly through animal yards. Visitors to the zoo last spring and fall reported watching mice crawl over sleeping gorillas to grab the apes' food -- a sight that one patron said "gave me the heebie-jeebies."

In November, a colobus monkey died from leptospirosis, a bacterial disease transmitted by rats and other wild animals.

The rodent problem has drawn complaints from the U.S. Department of Agriculture and the National Academy of Sciences, which has been conducting a study of animal care at the zoo. In an interim report in February, the science panel warned that pest control was inadequate and "poses a potential threat to the animal collection, employees and visitors."

The latest rodent-control efforts come a year and a half after the accidental poisoning of two male red pandas, an endangered species. The animals died in January 2003 after a pesticide contractor buried poison gas pellets in rat holes in their yard in an aggressive attempt to fumigate the rats.

A zoo pathologist found that the pandas had eaten tiny pieces of the poison that fell on the ground while the pellets were being buried.

After the red panda deaths, zoo officials fired the contractor and abruptly halted the use of rodent poison anywhere in the park, including non-animal areas -- a decision that employees say allowed the grounds to be overrun by vermin.

"Not having a contractor here for so long, everything had gotten out of control, from the rats down to the flies and mosquitoes," said Alberts, an entomologist.

Zoo Director Lucy H. Spelman hired Alberts as part of an overhaul of pest control operations she ordered after the red pandas died.

Alberts said that when she started her job in November, she found so many problems that she didn't know where to start. Walking the zoo grounds recently, she pointed out numerous exhibits that had been besieged by rodents.