Giant Kangaroo Rat

Giant Kangaroo Rat

Basics of the Kangaroo Rat

The Giant Kangaroo rat, Dipodmys ingenus, is a small rodent with a motely set of features seen in other more common rodents such as the common mouse and pocket mice as well as features of the kangaroo. From head to its long, tufted tail, the giant kangaroo rat is around 5.9in long and weighs about 150 grams. The giant kangaroo rat moves similarly to a kangaroo, using both of its large hind legs to hop around, while its short forearms remain close to its torso.  Other physical features include a short neck, cheek pouches for storing food, and a flat head.  

More recent estimates of the Giant Kangaroo Rat's distribution hints towards the species' more grim state of existence.  Compared to the aforementioned estimates from the 1950's, Giant Kangaroo Rat populations have been fragmented into 6 primary division, each of which is broken down into a total of 100 isolated habitats.

Geographic and Population Changes

This rat lives in burrows often in mounds of sand or soft soil. The soft material is necessary because burrowing is difficult for the rodent due to its very short front arms. Often times the Kangaroo rat will move its residency to a different burrow depending on the population density of its environment. To learn more about these burrows check out this link: 

http://www.cdpr.ca.gov/docs/endspec/espdfs/krattrax.pdf

Figure 1 shows that Kangaroo rats living in environments of high population density are more likely to stay in their natal burrow until their siblings or mother rat kicks them out of the nest. Low population density areas are the opposite for these rodents and if burrows are open nearby, some kangaroo rats will leave these nest as early 11 months after birth. The reproductive ability of Giant Kangaroo Rats are largely dependent on two factors, population density and availability of food. Since the population density has clear effects on Giant Kangaroo Rat population dynamics, Figure 1  is important to understand, specifically in how population density often mirrors plant productivity.

Looking back to known population distributions and accounts of Giant Kangaroo Rat inhabitants as early as in the 1950s, the animal was well distributed across an expansive section of California and parts of Nevada.  Likely due to the land structures capability to allow Giant Kangaroo Rat's to build burrows, the animal was often found, to name a few landmarks, along slightly sloped grounds near the west of the San Joaquin Valley, towards the south near the Tehachapi Mountains, North of Merced County, and occasionally on steeper grounds near Tumey Hills and Panoche Valley.  Throughout this general area, the estimated habitat for the Giant Kangaroo Rat was, at most, 631,724 hectares[pg. 85].

Figure 1: A car graph showing the population density of the Giant Kangaroo Rat over 9 years

Listing Date and Type of Listing

After the enactment of the Endangered Species Act and the research done on declining Giant Kangaroo Rat populations, the animal was listed as an endangered species on January 5^th in 1987.  As mentioned in Section 4 of the ESA, due to the fragmentation and overall decrease to 1.8% of their natural habitat, the species was clearly“...in danger of extinction throughout all or a significant portion of its range...” Figure 2 shows a map of the isolated populations of Giant Kangaroo Rats in California in 1995.

Figure 2: A Map showing the populations of Giant Kangaroo Rats in Central Calidornia.

           

The U.S Fish and Wildlife Service finalized a recovery plan for the species on September 30^th, 1998 after identifying population dynamics and probably reasons for the species' endangerment.  Fortunately, the implementation of the Recovery Plan for Upland Species of the San Joaquin Valley, California has turned around the state of the Giant Kangaroo Rat.  As mentioned throughout sources discussing the Giant Kangaroo Rat's progress on the U.S Fish and Wildlife Service, specifically in the Implementation Progress Table and the 5-year review, posted on February 16^th, 2010 , the animal has been down-listed to Threatened, despite the Environmental Conservation Online System's “Listed FWS/Joint FWS and NMFS Species and Populations with Recovery Plans (sorted by Listed Entity)” table still stating that the species is endangered.

Cause of listing and Main threats to its continued existence

Compared to most other reasons, loss of habitat and habitat destruction were the prime reasons for the Giant Kangaroo Rat being listed as endangered.  Prior to the early 1970's, most of the animal's range had been left alone from human, industrial interests and effects.  It wasn't until the development of the San Luis Unit of the Central Valley Project and the California Aqueduct of the State Water Project that the Giant Kangaroo Rat's native environment began to shift.    By 1979, nearly all of the natural areas, specifically gentle slopes, were taken over for agricultural irrigation as most of the aforementioned areas were publicly owned. 

Description of Recovery Plan

The  Recovery Plan for Upland Species of the San Joaquin Valley, California submitted by the U.S fish and Wildlife Service formally recognizes that the full recovery of the Giant Kangaroo Rat will be successfully accomplished when “the three largest populations (western Kern County, Carrizo Plain Natural Area, and the Panoche Region) and the populations in the Kettleman Hills, San Juan Creek Valley and Cuyama Valley are protected and managed appropriately” [pg. 94].  More specifically, after more accurate models regarding their population changes, the Giant Kangaroo Rat's primary populations must be protected and that local populations are able to self-sufficiently maintain stable birthrates and decreased mortality rates.  It is recognized that, generally, breeding factors aren't currently harming the species, it is imperative that the species' is allocated larger, protected areas to ensure survival after any random catastrophic event.

Several actions have already been taken, following the outline laid out by the recovery plan. One of which is familiarizing land owners, who would normally have conflicting interests with preserving Giant Kangaroo Rat populations, with the beneficial effects that can come about with the recovery of the these populations. In addition to just informing land owners, to fulfill the goal of securing land for the Giant Kangaroo Rat, an ongoing effort is being made to coordinate older farmlands and eventually convert them to land suitable for the endangered species.

What can you for to save the Giant Kangaroo Rats

If you are on private property that can be suitable to house a burrow of Kangaroo rats, make it known to the FWS that you can house these adorable creatures. If you don't own a property that could house kangaroo rats there's not much you can do. However with the recovery program in place, the Giant Kangaroo Rat will be able to thrive in the San Joaquin Valley.

Figure 4: A Giant Kangaroo Rat jumping out of its burrow.

Sources

"Species Profile for Giant Kangaroo Rat (Dipodomys Ingens)." Species Profile for Giant Kangaroo Rat (Dipodomys Ingens). US Fish and Wildlife Service, 21 May 2010. Web. .

Williams, Daniel F., Elllen A. Cypher, Patrick A. Kelly, Karren J. Miller, Nancy Norvell, Scott E. Phillips, Cheryl D. Johnson, and Gary W. Colliver. "Recovery Plan for Upland Species of the San Joaquin Valley, California." (n.d.): n. pag. Environmental Conservation Online System. US Fish and Wildlife Service, 30 Sept. 1998. Web. .