New digs for Stephens’ kangaroo rats

Under a warm moon and a gentle wind, three dozen Stephens’ kangaroo rats burrowed into their new homes in rural Riverside County last week.

There were no coyotes present. That was good for the kangaroo rats. The U.S. government considers the rats a protected species; the coyotes consider them delicious.

Maybe the coyotes were scared off by mountain lion urine that had been sprinkled around the Southwestern Riverside County Multi-Species Reserve, an expanse of shrubby hills between Diamond Valley Lake and Lake Skinner.

The coyote-versus-kangaroo rat situation is the kind of thing that San Diego Zoo scientist Debra Shier will be studying. Her master’s thesis was on the Stephens’ kangaroo rat (her doctoral dissertation was on the New Mexico prairie dog).

It doesn’t do much good to relocate the tiny rodents with the twitchy noses to safer surroundings, only to see them gobbled up.


Shier has an affection for the diminutive creatures. Not everyone shares her feelings; the kangaroo rat is in a class with the snail darter, spotted owl and delta smelt as alleged threats to the (human) economy.

The Stephens’ kangaroo rat, native to Riverside and San Diego counties, has been blamed for halting residential development and freeway construction and increasing the risk of fire because federal law makes it illegal to destroy its habitat.

In 1995, the Riverside County Farm Bureau challenged the idea that the rats merit such protection. In August, the U.S. Fish and Wildlife Service rejected that challenge — and a similar one filed in 2002. The farmers may appeal.

A program between the reserve and the zoo’s Institute for Conservation Research gathers up kangaroo rats and takes them to safer areas that have the kind of bunch grass and chaparral they like for food and cover.

In this, the third year of the program, 150 of the nocturnal animals were moved. Last year, 130 were relocated, and 50 in 2008. There will be more next year.

This year’s were outfitted with radio transmitters so their movements can be followed. The transmitters had to be tiny; a kangaroo rat that measures 4 inches in length and weighs 62 grams is considered robust.

The kangaroo rats were trapped in late September from colonies on private land and taken in cages to the release area. Researchers hope they’ll re-create their former neighborhood. “We know who lived next to whom,” Shier said.

Whether the rats settle in the same way as their previous colony could be important as conservationists look for other ways to keep the species from going extinct.

Until they could burrow, however, the rats were vulnerable to coyotes. That’s where the mountain lion’s urine came in.

“It’s amazing,” Shier said. “You can order mountain lion urine on the Internet.”