Kangaroo Rat

The kangaroo rat is a rodent found in the deserts of North America. Though they are colloquially often called rats, they are more closely related to gophers. As their name may refer, they hop in a manner similar to a kangaroo.

These tiny creatures are known for their capability to jump great distances at high speeds of almost 6 mph to avoid being captured by predators.

Description

Length: 3.5 to 5.5 inches (8 -14 cm)

Weight: 2.5-6.0 oz (70-170 g)

Body and Coloration: These rodents are four-toed, with shorter forelimbs than the hind ones. Their heads are large compared to the rest of their bodies, with fur-lined cheek pouches. The tails of these rodents are longer than the rest of their bodies, almost 5.5-6.5 inches long, ending in a tuft.

Sexual dimorphism exists in the form of their sizes, as the males tend to be larger than their female counterparts.

The color of these species ranges from gray to buff, with the ventral side being lighter than the dorsal region.

Range and Distribution

Kangaroo rats are found in western and southwestern North America.

Habitat

They inhabit desert or semi-desert areas that have sandy soils suitable for burrowing.

Diet

These rodents are herbivorous, with seeds of creosote bush, grama grass, mesquite, ocotillo, and purslane forming a major part of their diet. They store these seeds inside their cheek pouches or in special seed caches. Due to the vast majority of their diet consisting of seeds, they are often referred to as granivorous mammals, i.e., those that mainly eat grains.

Sometimes they eat other vegetation and even insects at times of scarcity.

Lifespan

Kangaroo rats generally live for 2-5 years on average.

Behavior

• Despite these rodents being found in close proximity to each other, they remain solitary and are fiercely territorial. Males and females only interact during the mating season, even if their territories overlap.
• They are nocturnal, being active at night. During the day, they remain underground to avoid predators and the overbearing heat of the day.
• Kangaroo rats will sometimes employ a unique ability colloquially referred to as the “move freeze” technique. When it detects a predator observing them, they will become perfectly still before suddenly moving away at a blinding speed.
• Communication occurs primarily by drumming their feet, though they are quite capable of producing vocalizations.
• Males tend to be more aggressive than females, with the latter interacting less violently with other members of their sex. The reason could be that the territories of the female kangaroo rats barely overlap, but that is not the case for their male counterparts.
• They will often clean themselves with fine sand; if they do not do so, they will often develop body sores and matting in their fur.

Predators

These little rodents have several predators, including badgers, bobcats, coyotes, foxes, owls, ringtails, and snakes. 

Adaptations

• The kangaroo rat has very powerful hind limbs that they use to move about bipedally and leap up to heights of 9 feet. They can even change directions mid-jump.
• They have several adaptations to conserve water to survive in the desert. These include reabsorbing moisture from their breath via their nasal passages, having oily coats that retain water, and not sweating.
• Their senses are very keen, with large bony structures present in their ears that let them hear even the slightest sound . They also have large eyes to see clearly in the dark.
• The color of their coats matches their sandy surroundings, giving them effective camouflage.

Mating and Reproduction

They are promiscuous, with many males reproducing with the same female in certain species like the Merriam’s kangaroo rat. Their reproductive rate is highly dependent on rainfall, with several females not willing to reproduce during periods of drought and food scarcity.

Before mating, the male and female circle each other and engage in a nasal-anal activity. After this, the female lets the male mount her.

Life Cycle

After a gestation period of 22-27 days, the female gives birth to a litter of 1-6 blind, hairless young.  The baby kangaroo rats develop their hind legs over 2-3 weeks, moving about by crawling until then. Once that period has passed, they become independent and are weaned at around 22-25 days, though they remain in their nest for 1-6 months.

Most species of kangaroo rat reach sexual maturity at around 2 months.

Conservation Status

While most kangaroo rats are classified as “Least Concern” or “LC” by the IUCN, a few are at a little more risk than the rest. These include the Banner-tailed kangaroo rat, which is “Near Threatened” or “NT”, the Fresno, Texas, and Stephen’s kangaroo rats which are “Vulnerable” or “VU”, the giant kangaroo rat, which is “Endangered” or “EN”, and the San Quintin kangaroo rat which is “Critically Endangered” or “CR”.

Interesting Facts

• British zoologist John Edward Gray, FRS, would first describe this genus in 1841.
• The genus name comes from the New Latin words dipodo, which means two feet, and mys, meaning mouse. It was probably named so due to the resemblance of the rodent to a mouse moving on two legs.
• While both have long legs and live in arid areas, the jerboa and the kangaroo rat are separate animals. An easy way to tell the two apart is the size of their ears, with jerboas having more prominent ears than the kangaroo rat.