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Sula Vanderplank, San Diego Natural History Museum

Supposedly extinct kangaroo rat resurfaces after 30 years

The last time anyone saw the San Quintin kangaroo rat was more than 30 years ago, in the arid scrublands of Baja California in Mexico. Mexican authorities declared the small mammal critically endangered, and possibly extinct, in 1994. So biologists couldn't believe their eyes when not one, but four San Quintin kangaroo rats (Dipodomys gravipes) hopped into their survey traps in 2017.

Named for their ability to leap like kangaroos, the rats are key species in arid areas across western North America, dispersing seeds and feeding predators such as coyotes and foxes. The San Quintin kangaroo rat is about 12 centimeters long, with a long, tufted tail and enormous hind legs that allow it to leap about 2 meters and speed away at 10 kilometers per hour. They once lived by the thousands in a narrow coastal valley stretching 150 kilometers along the Pacific coast of northern Baja California.

But their numbers began to dwindle with the introduction of intensive agriculture in the 1970s, after which their habitat and food disappeared. Then, just 9 months ago, a team of researchers doing a routine inventory of mammals in the region discovered the rats in their survey traps. None of them had ever seen the species before, so they had to compare it with museum specimens and photographs, they will report in an upcoming issue of the Bulletin of the Southern California Academy of Sciences

The researchers attribute the kangaroo rat's comeback to a dramatic decrease in farming over the past decade, thanks to drought-related water shortages. Although the researchers are concerned that farmers may eventually make their own comeback, they are optimistic that the San Quintin kangaroo rat will persist, as it has also shown up in a nearby nature reserve. They say it also offers hope for other "extinct" small mammals, which may be findable if only researchers take the time and effort to track them down.