- Endangered, federal Endangered Species Act
- Endangered, state Endangered Species Act
The endangered giant kangaroo rat is not your typical household rodent – in fact they are not even closely related. This small furry mammal bounces around on its large hind legs, which are also used for thumping on the ground to communicate with fellow k-rats. Found near the Los Padres National Forest and in the Carrizo Plain National Monument, the giant kangaroo rat is able to survive severe drought by obtaining all the water it ever needs from the seeds it collects and stashes in underground burrows. With more than 98% of its habitat gone, the giant kangaroo rat continues to be threatened by agricultural and urban development, rodenticides, and oil drilling and exploration.
Keystone Species of the Carrizo Plain
The giant kangaroo rat is the keystone species of the Carrizo Plain, serving as the foundation for the entire ecosystem. If the kangaroo rat’s population drops, it could mean real problems for other imperiled critters like the San Joaquin kit fox, the blunt-nosed leopard lizard, and the San Joaquin antelope squirrel. The giant k-rat’s burrows provide shelter for squirrels and lizards, and they are a favored part of the kit fox’s diet. Without them, the entire ecosystem would go out of whack.
The giant kangaroo rat was declared a state endangered species in 1980 and federally-listed as endangered in 1987, after more than 98% of its habitat was destroyed. Historically, its range included the whole western edge of the San Joaquin Valley, stretching from the Tehachapi Mountains to eastern San Luis Obispo County, but it is now limited to the southwestern edge of the San Joaquin Valley, including the Carrizo Plain, Elkhorn Plains, Kettleman Hills, and Cuyama Valley. The primary cause of this habitat loss was conversion of lands in the San Joaquin Valley to agriculture. Additionally, the use of rodenticides to control ground squirrels killed much of the remaining populations of giant kangaroo rats.
Drummers on the Plain
The giant kangaroo rat is the largest of some 20 species of kangaroo rats. The giant kangaroo rat measures about 13 inches from nose to tail when full grown, and this includes a 7 inch long tail, which has a characteristic tuft of fur on the end, and weighs a little over 5 ounces. As with other kangaroo rats, the giant kangaroo rat has large hind legs, which it uses not only for hopping around but also for communication. Giant kangaroo rats will often drum the dirt with these hind legs as a warning of approaching danger and to declare territory. A single kangaroo rat’s territory stretches around 20 feet in diameter, and is found within a colony that can consist of thousands of core areas within a larger territory. Giant kangaroo rats feed primarily on the seeds of grasses and shrubs and are most active during the spring, when these seeds are ripe. The animals remain active year-round, however, feeding at night, primarily for the first two hours after dark. Within its individual territory, a giant kangaroo rat will maintain a number of shallow pits, which it uses to dry seeds before storing them in their underground burrows, as well as patches of dirt is uses for “dust baths.” These baths apparently help the animal maintain good skin and fur condition, and facilitate marking of its territory. The kangaroo rat will also maintain several entrances to its burrow, and several underground compartments, in which it stores its food and bears young.
Adapted to Survival
After drying its seeds on the surface, the giant kangaroo rat will move the seeds to its cool, moist, underground burrow, where they swell with moisture, providing the animals all the water they ever need—the giant kangaroo rat never has to take a drink! This ability, and the practice of collecting and storing a large amount of seeds, allows the kangaroo rat to survive severe drought for extended periods of time. This is a very important adaptation for the giant kangaroo rat, as its grassland and shrubland habitats typically receive less than 15 inches of rain per year, and during the summer daytime temperatures reach greater than 100 degrees on average. Giant kangaroo rats are also relatively adaptable to changing food and population conditions. When food is abundant and population densities low, females can produce litters of up to 6 young, and can produce as many as 3 litters per year. Contrarily, when food is scarce or population densities high, females can produce fewer young and may only have one litter during the year. The majority of prime habitat for the giant kangaroo rat is now found only in areas of the Cuyama Valley and Carrizo Plain. While the species has not yet been found on Los Padres National Forest lands, surveys have been limited and about two thousand acres of potential habitat occur on the forest near the Cuyama Valley. On National Forest lands, the Forest Service is currently evaluating whether to conduct additional surveys to determine if giant kangaroo rats are found on the forest, and whether or not to reintroduce the species to areas with viable habitat on forest lands.
Meanwhile, the giant kangaroo rat continues to be threatened by urban and industrial developments, oil and mineral exploration and extraction, new energy and water conveyance facilities, and construction of communication and transportation infrastructures, which destroy giant kangaroo habitat and further fragment populations. Oil drilling in particular is now becoming a serious threat to the population of giant kangaroo rats on the Carrizo Plain, as oil companies recently proposed to explore for oil in the heart of the national monument.