This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American
Thirty years. That’s how long it’s been since anyone has seen the super-cute Morro Bay kangaroo rat (Dipodomys heermanni morroensis) in the wild. Does that mean it’s extinct?
Not so fast. According to a paper published this month in the Journal of Fish and Wildlife Management, the Morrow Bay kangaroo rat could just possibly be hanging on in the tiny scraps of its California habitat that remain.
Of course, there’s not much of that habitat left to actually support this tiny rodent. At least 99 percent of the dune-adapted kangaroo rat’s former habitat has been paved over, so if they’re still out there, there can’t be many of them.
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The Morro Bay kangaroo rat wasn’t always this rare. Back in 1957 the population was estimated at about 8,000 animals with a habitat of around 650 hectares. That quickly whittled away as development took over this little coastal area, located about 40 kilometers north of Pismo Beach. Back in 1982 the U.S. Fish and Wildlife Service—which listed the rat under the precursor to the Endangered Species Act back in 1970—warned that the human population in the area had grown 600 percent and the a “building boom” had replaced the rat’s habitat with “homes, gardens, shopping centers, parking lots and roads.”
The effect of that development added up quickly. By 1985 the kangaroo rat’s population was estimated at just 51 animals living within 13.3 hectares of habitat. The next year was the last time a wild member of this subspecies was seen alive. The last captive individual, meanwhile, died in 1993.
People kept looking for it, though. The authors of the new paper, Christopher Kofron from FWS and Francis X. Villablanca from California Polytechnic State University, conducted extensive field surveys from 2008 to 2012. They say they saw potential signs of the kangaroo rat at two sites in 2011. They didn’t observe any actual animals, but they did find burrow entrances, tail drag marks and surface seed pit caches typical of the rats’ presence. That, they write, is enough to suggest that the rat may still exist “at extremely low densities in a few isolated colonies.”
Kofro and Villablanca haven’t given up, but they wrote that their old methods—setting traps with oatmeal and peanut butter—may no longer be effective for such a small population. They suggest switching to using sniffer dogs or camera traps pointed at bait stations that could be more effective at detecting these extremely rare, nocturnal, burrowing rodents than the human eye.
Meanwhile, could the Morro Bay kangaroo rat be hiding elsewhere? The two sites with possible sightings were on public land. Four additional possible habitats still exist, but they’re all on private land. Kofro and Villablanca said the owners denied them permission to search. The kangaroo rats, the researchers suspect, could still be hiding on those four locations. Unfortunately without access, we may never know for sure.