Neotoma martinensis

Geographic Range

Neotoma martinensis , the San Martin Island woodrat, is an extinct species that was endemic to San Martin Island, which is offshore from San Quintin on the west coast of Baja California, Mexico. Also endemic to the islands off the coast of Baja California are the two extinct species Neotoma anthonyi and Neotoma bunkeri , and the endangered species Neotoma bryanti . These endemic island species, including Neotoma martinensis are all believed to belong to the N. lepida species group, which is found in western North America and throughout Baja California. Neotoma martinensis , Neotoma anthonyi , and Neotoma bryanti are believed to have been derived from the mainland species N. lepida when there was a land bridge between the islands and Baja California. The N. lepida species group is one of four species groups within the genus Neotoma . Based on recent research, this species group is monophyletic with two major clades that includes Neotoma species located within the regions of Arizona, California, Nevada, Utah, and Mexico.

• Other Geographic Terms
• island endemic island endemic

Habitat

San Martin Island is in the Upper Sonoran life zone where succulents, lichens and cacti are common. The island is part of a volcanic belt; there is no fresh-water on the island, but the volcanic surface created many caves, cavities, and crevices, where water could accumulate. Neotoma martinensis (and other woodrats on their respective islands) prefered rocky or mountainous areas so they could build nests within the volcanically created cavities as well as on top of cliffs. Nests were made from thorny vegetation, stones, bones, leaves, or anything else the woodrats could carry. Although Neotoma martinensis would generally build their nests on top of cliffs, some individuals would place conical nests on flat ground composed mainly of sticks and other debris. Nests were very important to their survival since woodrats have not adapted well to living in extremely hot conditions. Not much else is known regarding the habitat preference for Neotoma martinensis , but its mainland derivative, N. lepida , prefers habitats with succulents, juniper sagebrush, creosote brush, and cholla cactus vegetation, since their main water source comes from the water cached in these plants. Neotoma lepida can also be found in salt marshes, scrub of riparian zones, chapparals, Joshua tree woodlands, scrub oak woodlands, and piñon-juniper woodlands. The critical feature that identify preferred habitats for woodrats are the physical characteristics that create protection from predators (i.e. crevices, rock piles, alcoves).

• Habitat Regions
• tropical tropical
• terrestrial terrestrial

• Terrestrial Biomes
• desert or dune desert or dune
• chaparral chaparral
• scrub forest scrub forest

• Other Habitat Features
• caves

Physical Description

Neotoma martinensis had a dark, relatively long and tapered tail containing few hairs, which distinguishes it from N. lepida . The San Martin Island woodrat closely resembled N. anthonyi from one of the neighboring islands, but had larger ears that were a creamy buff color, purer white underparts, and different cranial characteristics. In males, the length of ears ranged anywhere from 29 - 36mm. The head of Neotoma martinensis was dark from the presence of dusky hairs, but gradiented on the sides to become lighter, becoming creamy white on the underparts of the animal. Length of the head and body ranged from 169 - 206mm, and the length of the tail ranged from 130 - 168mm. The hind legs were black on the outer sides, and the upper sides of the forelegs were dusky brown while the feet were pure white.

The skull size of Neotoma martinensis was medium and smoothly rounded with high anterior roots of the zygomatic arches. These arches narrowed out anteriorly, while the nasal bones were very long and thinned out posteriorly, past the lachrymal. Temporal ridges were indistinct and widely separated. Branches of the premaxillae reached past the nasal bones toward the infraorbital foramen. The top surface of the frontal lobe was quite flat and had under-developed lateral ridges. The auditory bullae were rather small and pear-shaped with a very large auditory canal. This large auditory canal then created a wide external opening from the skull.

These woodrats exhibited an increase in sexual dimorphism compared to the mainland species; the males had a slightly larger head and body than the females. Males averaged to be about 194 mm in length whereas females were 176 mm (head to body).

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• male larger

Reproduction

The specific mating system for Neotoma martinensis is not known. However, males and females of N. lepida , the mainland derivative of Neotoma martinensis , are known to have multiple mates. Also, N. lepida males are not known to play a role in raising young, which is seen in most Neotoma species.

• Mating System
• polygynandrous (promiscuous) polygynandrous (promiscuous)

Nothing is specifically known about reproduction in Neotoma martinensis , although it is likely that Neotoma martinensis had similar reproductive qualities as other Neotoma species. Females in the genus Neotoma are known to produce up to five litters a year, but two litters are typically seen on average in late winter or spring. Gestation period lasts 30 to 36 days with an average of two to three offspring per litter. Once young are born, mothers will lick their newborns as a means of recognition. Newborn weight and age at which offspring are weaned depends on litter size. In the case of two offspring, it takes about 21 days to be weaned. When there are four offspring, weaning can take up to 34 days. Once young reach about two to three months of age, females are able to become sexually active again. Nesting is solitary; therefore it is believed that males are not involved in rearing young.

• Key Reproductive Features
• iteroparous iteroparous
• year-round breeding year-round breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• viviparous viviparous

Parental investment is not well known for Neotoma martinensis ; however, most Neotoma species demonstrate very little parental care. Males do not play a role in raising young. Females will spend about two or three months raising the young before becoming sexually active again.

• Parental Investment
• no parental involvement
• altricial altricial
• female parental care female parental care
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female
• pre-weaning/fledging
  • provisioning
    • female
  • protecting
    • female

Lifespan/Longevity

Nothing is specifically known about the lifespan of Neotoma martinensis . In the woodrat species N. lepida , the mainland derivative of N. martinensis , individuals live to about 3 years in the wild and up to 10 years in captivity. In other Neotoma species, like N. micropus and N. albigula , individuals can live from 2-6 years in the wild.

Behavior

Nothing is specifically known about the behavior of Neotoma martinensis . Woodrats, as a genus, are very good climbers and will often place their nests in high elevations, like cliffs, mountain tops, etc., to avoid predation. They are active yearlong and mainly nocturnal, but can be crepuscular. Woodrats are not well adapted to extreme thermal conditions and most individuals will not become active until temperatures are below 105°F. When temperatures begin to increase, individuals will greatly reduce the frequency of leaving their nests. Woodrats are solitary and territorial animals. They tend to remain within their home ranges and will avoid crossing boundaries of other individuals.

• Key Behaviors
• nocturnal nocturnal
• crepuscular crepuscular
• motile motile
• sedentary sedentary
• solitary solitary
• territorial territorial

Home Range

There is no specific information known regarding home ranges of Neotoma martinensis . However, home ranges in woodrats are typically about 7 to 10 meters and usually revolve around succulents or cacti, which serve as the main water source for woodrats. Territories are equivalent to the individual's home range, therefore woodrats will defend any succulents in their territory from other species. Males are known to have larger home ranges than females. Seasonal changes will affect home range sizes, but females remain closest to their nests, and rarely venture outside their home range when they are nursing.

Communication and Perception

Nothing is specifically known about communication and perception in Neotoma martinensis , but the mainland species N. lepida uses scent marking prior to social encounters. Males of N. lepida will exhibit ventral rubbing, which is occasionally demonstrated by females. This behavior involves rubbing an oily, musky-smelling secretion produced by large ventral sebaceous glands on the ground in a roll and sliding motion. Females typically display a rolling behavior as a sign of estrus where the individual will dig a small depression in the ground and roll on one side of its body.

During breeding season, many species of male woodrats will often emit vocalization before, and sometimes during, copulation. In some species, males are able to produce ultrasonic vocalizations. Prior to copulation, a series of behaviors are often displayed in woodrats: there is first an approach and break-off, where one individual will move away from the other. Then there is sniffing of the head and anal-genital region. Males will engage in anogenital sniffing in response to female odors. Females will also approach and engage in anogenital sniffing of the males. One individual will then demonstrate a "boxing" behavior where he or she stands upright to face their partner and pushes them with their fore-paws. Then a simultaneous foot thumping of the hind-leg is exhibited with a side-to-side tail wag. Copulatory behavior begins with a hop-darting motion demonstrated by the female to engage the male. The male will begin to chase the female during this behavior and emit a rasp vocalization. At this point the male will approach to mount and the female will go into lordosis, where she will arch her back and extend her hind legs to prepare for intromission.

• Communication Channels
• acoustic acoustic
• chemical chemical

• Other Communication Modes
• pheromones pheromones
• scent marks scent marks

• Perception Channels
• tactile tactile
• acoustic acoustic
• ultrasound ultrasound
• chemical chemical

Food Habits

Neotoma martinensis was the only terrestrial herbivore on San Martin Island. Woodrats in general are known to hoard food and tend to feed on grass, leaves, fresh fruit, small bulbs, bark, and cactus stems. Some woodrat species will eat nuts, dry seeds, or fungi. Similar to other members of the genus, Neotoma martinensis preferred herbs, leaves, seeds, and cacti fruit.

• Primary Diet
• herbivore herbivore
  • folivore folivore
  • frugivore frugivore
  • granivore granivore

• Plant Foods
• leaves
• seeds, grains, and nuts
• fruit

• Foraging Behavior
• stores or caches food stores or caches food

Predation

Woodrats in general have many predators like owls, hawks, snakes, cats, coyotes, foxes, and weasels. Neotoma martinensis ultimately met its demise from the combination of predation by owls and introduced feral cats on San Martin Island.

Ecosystem Roles

Nothing is specifically known about the niche of Neotoma martinensis . In the genus Neotoma , competitors involve other herbivorous rodents. Abandoned nests are typically reclaimed by a variety of small vertebrates for shelter or refuge from predators. Woodrats have also been found to carry bot fly larvae, various species of mites and chiggers ( Acarina ), lice ( Anoplura ), and fleas ( Siphonaptera ), and the Whitewater Arroyo virus, an arenavirus that causes hemorrhagic fever. Woodrats act as reservoirs for this virus by inhaling fecal matter of other woodrats. Some endoparasites known to be associated with woodrats are acanthocephalans ( Acanthocephala ) and roundworms ( Nematoda ). It is possible that Neotoma martinensis may also have been parasitized by some of these species.

Economic Importance for Humans: Positive

There is no known positive impact that Neotoma martinensis or many other Neotoma species have had on humans. Any kind of economic benefits towards humans occurred indirectly through their niche and the ecological role they play on their environment. Although one Neotoma species, N. fuscipes has been found have some value in their feces, as it is often used for fertilizer in some parts of California.

Economic Importance for Humans: Negative

Woodrats in general can be considered a nuisance since they are packrats, taking small objects as they see fit. Neotoma martinensis used to be controlled by burning brush and introducing cats (from Japanese fisherman that occupied San Martin Island) to hunt the woodrats. Not much else is known regarding Neotoma martinensis , but in the mainland relative, N. lepida , some individuals have been found to carry the hantatvirus, which can lead to death in humans. Most Neotoma species are potential vectors for diseases and are overall considered pests.

• Negative Impacts
• injures humans
  • carries human disease
• household pest

Conservation Status

This woodrat species was declared extinct by the International Union for Conservation of Nature (IUCN) in 2008.

Additional Links

Encyclopedia of Life

Contributors

Angela Guajardo (author), Texas A&M University, Jessica Light (editor), Texas A&M University, Tanya Dewey (editor), University of Michigan-Ann Arbor.

References

Alvarez-Castañeda, S., P. Cortés-Calva, E. Yensen. 2001. Neotoma martinensis. Mammalian Species , 657: 1-3.

Brylski, P. 2008. Life history account for desert woodrat. California Wildlife Habitat Relationship System , 3: 126.

Ceballos, G. 2014. Mammals of Mexico . Baltimore, Maryland: JHU Press.

Edwards, C., R. Bradley. 2002. Molecular systematics of the genus Neotoma. Molecular Phylogenetics and Evolution , 29: 489-500.

Egoscue, H. 1957. The desert woodrat: a laboratory colony. Journal of Mammalogy , 38: 472-481.

Fleming, A., P. Chee, F. Vaccarion. 1981. Sexual behavior and its olfactory control in the desert woodrat (Neotoma lepida lepida). Animal Behavior , 29: 727–745.

Goldman, E. 1910. Revision of the wood rats of the genus Neotoma . North America: Fauna 31.

Jameson, E., H. Peeters. 1988. California Mammals Issue 52 of California natural history guides . California: University of California Press.

Jameson, E., H. Peeters. 2004. Mammals of California Issue 66 of California natural history guides . California: University of California Press.

Lacher, T., I. Castro-Arellano, S. Álvarez-Castañeda. 2002. "Neotoma bunkeri" (On-line). The IUCN Red List of Threatened Species. Accessed May 12, 2016 at http://www.iucnredlist.org/details/14577/0 .

Lacher, T., E. Vázquez, S. Álvarez-Castañeda, I. Castro-Arellano. 2008. "Neotoma bryanti" (On-line). The IUCN Red List of Threatened Species. Accessed May 12, 2016 at http://www.iucnredlist.org/details/full/14584/0 .

Orr, R. 1960. An analysis of the recent land mammals. Systematic Zoology , 9: 171-179.

Smith, F., I. Murray, L. Harding, H. Lease, J. Martin. 2014. Life in an extreme environment: a historical perspective on the influence of temperature on the ecology and evolution of woodrats. Journal of Mammalogy , 95/6: 1128-1143.

Smith, F. 1992. Evolution of body size among woodrats from Baja California, Mexico. Functional Ecology , 6: 265-273.

Verts, B., L. Carraway. 2002. Neotoma lepida. Mammalian Species , 699: 1-12.

White, N., A. Fleming. 1987. Auditory regulation of woodrat (Neotoma lepida) sexual behaviour. Animal Behavior , 35: 1281-1297.

Álvarez-Castañeda, S., I. Castro-Arellano, T. Lacher. 2008. "Neotoma martinensis" (On-line). The IUCN Red List of Threatened Species. Accessed May 12, 2016 at http://www.iucnredlist.org/details/14580/0 .

Álvarez-Castañeda, S., I. Castro-Arellano. 2008. "Neotoma anthonyi" (On-line). The IUCN Red List of Threatened Species. Accessed May 12, 2016 at http://www.iucnredlist.org/details/14576/0 .