Heermann's kangaroo rat

Heermann's kangaroo rat
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Rodentia
Family: Heteromyidae
Genus: Dipodomys
Species: D. heermanni
Binomial name
Dipodomys heermanni
Le Conte, 1853

Heermann's kangaroo rat (Dipodomys heermanni) is a species of rodent in the family Heteromyidae.[2]

Distribution

Dipodomys heermanni is endemic to California in the United States.[1] The range is limited as well, extending north to south from Lake Tahoe to Point Conception, and east to west from the Sierra Nevada mountain range to the Pacific Ocean.[3] However, even with this small home range, the Heermann's kangaroo rat is listed as a species of least concern according to the IUCN.

Home Range and Population Density

Home Range

With all the interconnected surface runways within a community composed of individual Heermann's kangaroo rats, it is incredibly difficult to narrow down individual home ranges.[4] Because of this difficulty in distinguishing home ranges, the estimated values fluctuate greatly.[4] In one study, more than half of all recaptured rats were found within 30.5 meters of their first capture.[4] Home ranges can be very different from each other and can consist of differing levels of vegetation.[3][4] Most common areas are on costal plains or ridges with shallow soil.[3][4]

Population Density

Population densities experiences many ups and downs and have been shown to range from 2-30 kangaroo rats per hectare.[4] There seems to be no way of predicting whether or not emigration has anything to do with these large fluctuations in population density.[3] Typically, it is only the larger rats that take part in emigration, and females have been shown to exhibit this behavior more often than males.[3][4]

Ecology and Behavior

Ecology

Heermann's kangaroo rats are burrowing animals, and the rats manipulate the tunnels already made by other burrowing animals to make their own.[3][4] The extent of the burrowing behavior highly depends on the type of soil present in their home range.[3][4] Heermann's kangaroo rats are granivores, which is the most important part of their diet.[3][4] The rats also are herbivores, and especially during seasons of winter and spring.[4] Most of the plant material near the burrows in their home ranges are utilized.[3][4] Heermann's kangaroo rat achieve necessary water consumption from seeds and dew from the plant material in their diet.[3][4][5] The rats will only drink from a puddle or direct water source if water intake isn't achieved for several weeks.[4][5] If the dry food matter increases and humidity is decreased, the mean daily activity of the rats drastically declines.[4][5]

Behavior

The kangaroo rat does not hibernate. Instead, it remains more or less active during the year depending on time of day.[3] Living in a burrow for the majority of the day and typically coming out only at night, The Heermann's kangaroo rat lives a solitary life.[3] However, experiments have shown that sociality does alter the rat's behaviors and that the rat does indeed have some ability to form generalized sociality.[4] Sociality is measured by willingness to participate in social interactions. Kangaroo rats exhibit their willingness to interact with each other with a characteristic foot drumming, where increased foot drumming was associated with unwillingness to socialize and the absence of foot drumming was associated with willingness to socialize.[3][4][6] High rates of interspecies competition has been observed; however, intraspecies competition between Heermann's kangaroo rats has not been directly observed.[7]

Reproduction

Heermann's kangaroo rat rarely show increase levels of sexual behavior.[3][8] Copulation is rather quick, and typically only lasts a couple seconds.[3][8] If the animals are caged, the rats show no increase in sexual behavior.[3][8] Females rats will even show aggression if her genitalia are swollen and enlarged.[3][8] During labor, the female rat will assist the delivery of the young with her front paws.[3][8] The female Heermann's kangaroo rats also fondle her babies after birth with fondling, smelling, and licking.[3][8]

References

  1. 1 2 Linzey, A. V. & Hammerson, G. (NatureServe) (2008). "Dipodomys heermanni". IUCN Red List of Threatened Species. Version 2008. International Union for Conservation of Nature. Retrieved 27 March 2009.
  2. ↑ Patton, J.L. (2005). "Family Heteromyidae". In Wilson, D.E.; Reeder, D.M. Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Johns Hopkins University Press. pp. 845–846. ISBN 978-0-8018-8221-0. OCLC 62265494.
  3. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 http://www.science.smith.edu/resources/msi/pdfs/i0076-3519-323-01-0001.pdf
  4. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Fitch, H. S., 1948. Habits and Economic Relationships of the Tulare Kangaroo Rat. Journal of Mammalogy. 29:5-35.
  5. 1 2 3 Nichters, R. (1957). "The effect of variation in humidity and water intake on activity of Dipodomys". Journal of Mammalogy.
  6. ↑ Shier, Debra M.; Randall, Jan A. (2007-05-01). "Use of different signaling modalities to communicate status by dominant and subordinate Heermann's kangaroo rats (Dipodomys heermanni)". Behavioral Ecology and Sociobiology. 61 (7): 1023–1032. doi:10.1007/s00265-006-0335-5. JSTOR 27823476.
  7. ↑ Tennant, Erin N.; Germano, David J. (2013-06-01). "Competitive Interactions Between Tipton and Heermann's Kangaroo Rats in the San Joaquin Valley, California". The Southwestern Naturalist. 58 (2): 258–264. doi:10.1894/0038-4909-58.2.258. ISSN 0038-4909.
  8. 1 2 3 4 5 6 Tappe, D. T. (1941). "Natural History of the Tulare kangaroo rat". Journal of Mammalogy.
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