Neotoma albigulaTurner Island woodrat(Also: white-throated woodrat)

Ge­o­graphic Range

Neotoma al­bigula oc­cu­pies a wide range of habi­tats in the south­west­ern United States and north­ern Mex­ico. The north­ern ex­tent of its range in­cludes the Four Cor­ners re­gion and the south­ern­most tip of Nevada. It can also be found as far west as south­east­ern Cal­i­for­nia and as far east as cen­tral Texas. It is dis­trib­uted widely through­out New Mex­ico and Ari­zona and through most of north­ern Mex­ico. (Cock­rum, 1982; Macedo and Mares, 1988; Zevel­off, 1988)

Habi­tat

Neotoma al­bigula ap­pears in a wide range of habi­tats in­clud­ing for­est edges, scrub­land forests, and low deserts, and can be found from 2135 m to 76 m in el­e­va­tion. It oc­ca­sion­ally builds dens in the caves of rocky hills, but more com­monly prefers areas of ex­ten­sive cholla and prickly pear cac­tus. Using cacti and other large desert plants as an an­chor, N. al­bigula builds an ex­ten­sive home using pieces of cacti, cow chips, sticks, bones, and any other found items, in­clud­ing garbage left by hu­mans. It is known for its large and com­plex shel­ters. Av­er­ag­ing 8 feet in di­am­e­ter and 2 to 3 feet in height, its shel­ters con­tain sev­eral cham­bers and un­der­ground tun­nels which are used to es­cape preda­tors. Each shel­ter also in­cludes a small un­der­ground nest that serves as a re­treat from day­time heat and as a place for fe­males to raise their young. The size of the nest av­er­ages about 8 inches in di­am­e­ter. It con­sists of soft ma­te­ri­als such as grasses or shred­ded fibers. The av­er­age den­sity of N. al­bigula shel­ters in heav­ily pop­u­lated areas is be­tween 5 to 15 per acre, but den­si­ties vary de­pend­ing on re­source avail­abil­ity. Neotoma al­bigula is a soli­tary species and houses are never co­hab­ited by adults. (Brown, 1968; Hoffmeis­ter, 1986; Macedo and Mares, 1988; Olsen, 1971)

  • Other Habitat Features
  • caves
  • Range elevation
    76 to 2135 m
    249.34 to 7004.59 ft

Phys­i­cal De­scrip­tion

In gen­eral, Neotoma al­bigula has a medium-sized body with brown­ish gray fur cov­er­ing dor­sum. The ven­ter is white or light gray with a white throat. The tail is shorter than the length of the body, is bi-col­ored and is cov­ered in mod­er­ately long hair. The ears are large and hair­less. Av­er­age mass is 197 g and av­er­age head-body length is 328 mm; how­ever, body size varies de­pend­ing on cli­mate, with larger spec­i­mens found in colder re­gions and smaller spec­i­mens found in warmer re­gions. Black color-morphs of N. al­bigula occur on lava beds in Texas and New Mex­ico. The species is fur­ther di­vided into 13 sub­species that oc­cupy over­lap­ping ranges through­out the south­west­ern United States and north­ern Mex­ico. Sub­species are dis­tin­guished pri­mar­ily by mor­pho­me­t­ric char­ac­ter­is­tics (e.g., body size). Av­er­age basal meta­bolic rate for this species is 36000 cm^3 oxy­gen/hour. Sex­ual di­mor­phism has not been doc­u­mented in N. al­bigula. (Cock­rum, 1982; Macedo and Mares, 1988; Zevel­off, 1988)

  • Average mass
    197 g
    6.94 oz
  • Average length
    328 mm
    12.91 in
  • Average basal metabolic rate
    36000 cm3.O2/g/hr

Re­pro­duc­tion

Mat­ing the only time that Neotoma al­bigula en­gages in so­cial be­hav­ior with adults con­specifics. Foot thump­ing often pre­cedes cop­u­la­tion, al­though the pur­pose is un­known. Dur­ing cop­u­la­tion, males and fe­males have lim­ited tac­tile con­tact and males do not clasp the fe­male. The av­er­age cop­u­la­tory lock lasts 30.1 sec­onds. It is hy­poth­e­sized that this short lock has evolved to min­i­mize pre­da­tion risk as cop­u­la­tion can cre­ate vul­ner­a­bil­ity to at­tack. Mate se­lec­tion be­hav­ior is not well un­der­stood. Neotoma al­bigula is promis­cu­ous and no bond­ing oc­curs be­tween mates after cop­u­la­tion. (Macedo and Mares, 1988)

Re­ports on the breed­ing sea­son of Neotoma al­bigula vary greatly. Some ob­ser­va­tions sug­gest year-round breed­ing, while oth­ers iden­tify a pe­riod be­tween Jan­u­ary and Sep­tem­ber as breed­ing sea­son. This dis­crep­ancy may be a re­sult of dif­fer­ences in breed­ing sea­sons among the dif­fer­ent re­gions oc­cu­pied and/or sub­species. How­ever, all sources agree that breed­ing slows dur­ing the hottest months of the year and that the ma­jor­ity of breed­ing takes place be­tween Jan­u­ary and June. Neotoma al­bigula can pro­duce mul­ti­ple lit­ters per sea­son, and fe­males are some­times found with off­spring of two dif­fer­ent ages in their dens. Av­er­age ges­ta­tion lasts 38 days, how­ever, ges­ta­tion pe­ri­ods short as 30 days have been recorded. Lit­ters range from 1 to 4 off­spring, with an av­er­age of 2 off­spring per lit­ter. Av­er­age birth mass is 10.9 grams. Wean­ing oc­curs be­tween 62 and 72 days, at which point off­spring have al­ready begun prac­tic­ing shel­ter con­struc­tion and con­sum­ing cacti, berries, and veg­e­ta­tion. In the wild, N. al­bigula reaches sex­ual ma­tu­rity at around 180 days. In cap­tiv­ity, in­stances of reach­ing sex­ual ma­tu­rity as young as 80 days in fe­males and 101 days in males have been doc­u­mented. (Macedo and Mares, 1988)

  • Breeding interval
    Neotoma albigula can breed multiples times per season. Females have been discovered caring for neotatal young and partially mature young simultaneously.
  • Breeding season
    Breeding begins in January but generally slows in mid-summer and may ceases in August or September depending on region and climate. Some researchers report year-round breeding.
  • Range number of offspring
    1 to 4
  • Average number of offspring
    2
  • Range gestation period
    30 to 38 days
  • Range weaning age
    62 to 72 days
  • Average time to independence
    7 months
  • Range age at sexual or reproductive maturity (female)
    80 to 300 days
  • Average age at sexual or reproductive maturity (female)
    180 days
  • Range age at sexual or reproductive maturity (male)
    101 to 300 days
  • Average age at sexual or reproductive maturity (male)
    180 days

Male N. al­bigula play no role in rear­ing the off­spring. Lit­tle is known about pre-con­cep­tion prepa­ra­tion for re­pro­duc­tion by the fe­male, al­though den con­struc­tion could be con­sid­ered part of her in­vest­ment. As is the case for all mam­mals, the mother uses her body to pro­tect the off­spring in utero. After birth, a fe­male lac­tates and feeds the off­spring her milk for 62 to 72 days. She cares for and pro­tects her young for ap­prox­i­mately 6 months until they have reached ma­tu­rity and dis­perse to build their own houses. A fe­male can have more than one lit­ter re­sid­ing in her home at one time, but only one lit­ter nurses at a time. Some sub­species are known to wean and ma­ture ear­lier than av­er­age, re­duc­ing parental in­vest­ment. (Olsen, 1971; Prakash and Ghosh, 1975)

  • Parental Investment
  • altricial
  • female parental care
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female
  • pre-independence
    • protecting
      • female

Lifes­pan/Longevity

Lit­tle is known on the lifes­pan of Neotoma al­bigula. The few ex­ist­ing data sug­gests that mem­bers of this species can live be­tween 3 and 5 years. Longest known lifes­pan in the wild is 6 years. (Zeng and Brown, 1989)

  • Range lifespan
    Status: wild
    72 (high) months
  • Typical lifespan
    Status: wild
    45 (high) months

Be­hav­ior

Neotoma al­bigula is pri­mar­ily noc­tur­nal, but some ob­ser­vors have re­ported day­time ac­tiv­ity within the den. It re­mains ac­tive year round. As a soli­tary species, it has very lim­ited so­cial in­ter­ac­tions; these occur be­tween adults only dur­ing cop­u­la­tion. The only other so­cial in­ter­ac­tion ex­pe­ri­enced by N. al­bigula is that be­tween a mother and her off­spring. Foot thump­ing is thought to be a form of com­mu­ni­ca­tion be­tween con­specifics in N. al­bigula and has been ob­served prior to cop­u­la­tion and as a re­ac­tion to preda­tory threats. Off­spring as young at 26 days old have been ob­served to par­tic­i­pate in foot thump­ing as a re­ac­tion to preda­tory stim­uli. (Cock­rum, 1982; Macedo and Mares, 1988; Olsen, 1971)

Nest con­struc­tion in­volves col­lect­ing many dif­fer­ent items. Neotoma al­bigula con­structs large nests that in­te­grate cacti, sticks, an­i­mal bones, cow chips and man-made ma­te­ri­als. Mem­bers of this species ap­pear to have a par­tic­u­lar affin­ity for col­lect­ing man-made ob­jects for in­cor­po­ra­tion into the nest. See Habi­tat sec­tion for ad­di­tional in­for­ma­tion. (Macedo and Mares, 1988)

  • Average territory size
    486 m^2

Home Range

Home ranges of Neotoma al­bigula av­er­age about 486 m^2 and nest den­si­ties av­er­age 5 to 15 every 4,000 m^2. Nests are sep­a­rated by an av­er­age dis­tance of 12 me­ters, caus­ing many home ranges to over­lap, which does not ap­pear to be a source of ag­o­nis­tic be­hav­ior among res­i­dents. Ter­ri­to­r­ial be­hav­ior near the nest has been ob­served. (Macedo and Mares, 1988; Olsen, 1971)

Com­mu­ni­ca­tion and Per­cep­tion

White-throated woodrats use scent to com­mu­ni­cate with con­specifics. Males have spe­cial­ized mid­ven­tral glands that they use to scent mark se­lected lo­ca­tions. In fe­males, this gland is poorly de­vel­oped. Pheromones are used in so­cial sit­u­a­tions in­volv­ing courtship, sex­ual, ag­o­nis­tic, hi­er­ar­chi­cal, and pos­si­bly ter­ri­to­r­ial in­ter­ac­tions. Pheromones pre­sent in feces are used to de­ter­mine the sex of den oc­cu­pants, thereby avoid­ing ag­o­nis­tic en­coun­ters be­tween males. White-throated woodrats rely upon scent and vi­sual cues to warn them of dan­ger from preda­tors. Al­tri­cial in­fants with un­opened eyes can­not dis­tin­guish a preda­tor by scent alone. (Macedo and Mares, 1988)

Food Habits

In desert habi­tats, Neotoma al­bigula feeds pri­mar­ily on cholla and prickly pear cac­tus. Neotoma al­bigula is not an ob­lig­ate drinker and ac­quires most of its water from cac­tus. Some ob­ser­va­tions es­ti­mate that the diet of N. al­bigula con­sists of up to 44% cacti. Dur­ing pe­ri­ods of ex­cep­tion­ally high tem­per­a­tures, N. al­bigula can eat up­wards of 60% of its body mass in cacti per day. While this species prefers cacti, it is con­sid­ered a gen­er­al­ist her­bi­vore. Other im­por­tant food items in­cludes the beans and bark of mesquite plants, ju­niper branches and berries, var­i­ous flow­ers, and yucca leaves. Neotoma al­bigula has also been ob­served con­sum­ing in­sects, small rep­tiles and mice, how­ever, such ob­ser­va­tions are un­com­mon. Neotoma al­bigula is known to store food through­out its large shel­ter. (Macedo and Mares, 1988; Olsen, 1971; Zeng and Brown, 1989; Zevel­off, 1988)

  • Animal Foods
  • mammals
  • reptiles
  • insects
  • Plant Foods
  • leaves
  • wood, bark, or stems
  • seeds, grains, and nuts
  • fruit
  • flowers

Pre­da­tion

Preda­tors of Neotoma al­bigula in­clude a num­ber of mustelids such as weasels, skunks, and bad­gers. Ad­di­tional mam­malian preda­tors in­clude racoons, red fox, gray fox, bob­cats, coy­otes, and ring­tails. Other im­por­tant preda­tors of N. al­bigula in­clude snakes and Great-horned Owls (Davis, 1960; Hoffmeis­ter, 1986; Macedo and Mares, 1988; Olsen, 1971; Prakash and Ghosh, 1975)

Al­tri­cial young are un­able to iden­tify preda­tors by smell alone and treat preda­tors as inan­i­mate ob­jects. Once their eyes are open, vi­sual clues play an im­por­tant role in preda­tor de­tec­tion for in­di­vid­u­als as young as 26 days. In preda­tory ex­per­i­ments, the re­ac­tion of Neotoma al­bigula to preda­tory stim­uli oc­curs in three steps: aware­ness of threat, foot thump­ing and in­creased ag­i­ta­tion, and fast and ran­dom di­rec­tion run­ning. Struc­tural adap­ta­tions to pre­da­tion are thought to have lead to ex­ten­sive tun­nels and cham­bers in and around the habi­ta­tion struc­tures of N. al­bigula. Tun­nels ap­pear to func­tion as a means of es­cape when faced with a po­ten­tial threat in or near the nest. A large pro­por­tion of N. al­bigula's shel­ter is con­structed from pieces of cacti. These spiny ad­di­tions act as a de­ter­rent for preda­tors, with­out in­hibit­ing the mo­bil­ity of N. al­bigula. Noc­tur­nal be­hav­ior likely re­duces risk of pre­da­tion. By re­main­ing in­side dur­ing the day, N. al­bigula avoids many preda­tors in­clud­ing many bird species and other di­ur­nal preda­tors. The col­oration of N. al­bigula likely helps cam­ou­flage them from po­ten­tial preda­tors as well. (Davis, 1960; Hoffmeis­ter, 1986; Macedo and Mares, 1988; Olsen, 1971; Prakash and Ghosh, 1975)

  • Anti-predator Adaptations
  • cryptic

Ecosys­tem Roles

The her­biv­o­rous diet of Neotoma al­bigula con­sists pri­mar­ily of cacti, their fruit and other desert veg­e­ta­tion. Its diet can alter the veg­e­ta­tion pro­file of the local area and may fa­cil­i­tate seed dis­per­sal. Shel­ter con­struc­tion and fecal dis­tri­b­u­tion can cause an in­crease in the amount of sol­u­ble salts, bi­car­bon­ates, and ni­trates in the soil. Once aban­doned, shel­ters can be in­hab­ited by a range of species in­clud­ing other woodrats, desert rep­tiles , and nu­mer­ous species of ro­dents. Par­a­sites spe­cific to N. al­bigula have not been doc­u­mented. (Macedo and Mares, 1988; Prakash and Ghosh, 1975)

  • Ecosystem Impact
  • disperses seeds
  • creates habitat

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

There are no known pos­i­tive ef­fects of Neotoma al­bigula on hu­mans, how­ever, there have been rare re­ports of hu­mans con­sum­ing N. al­bigula. (Macedo and Mares, 1988)

  • Positive Impacts
  • food

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

Neotoma al­bigula causes dam­age to cab­ins and sum­mer homes where it may oc­ca­sion­ally nest in the ab­sence of hu­mans. Dam­age to fur­ni­ture and other items that woodrats in­cor­po­rate into nests is not un­com­mon, and sig­nif­i­cant amounts of fecal waste have been left in ab­sent res­i­dences. Ad­di­tion­ally, N. al­bigula has been known to raid food stores that are poorly sealed. (Macedo and Mares, 1988; Zevel­off, 1988)

  • Negative Impacts
  • household pest

Con­ser­va­tion Sta­tus

Neotoma al­bigula is wide­spread and abun­dant through­out its ge­o­graphic range. As a re­sult, this species is clas­si­fied as "least con­cern" on the IUCN's Red List of Threat­ened Species.

Other Com­ments

An­other com­mon term for the white-throated woodrat is "pack­rat". This term refers to its ten­dency to cache man-made ob­jects.

Con­trib­u­tors

Maria Brym (au­thor), Uni­ver­sity of Michi­gan-Ann Arbor, Phil Myers (ed­i­tor), Uni­ver­sity of Michi­gan-Ann Arbor, John Berini (ed­i­tor), An­i­mal Di­ver­sity Web Staff.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

acoustic

uses sound to communicate

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

desert or dunes

in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

female parental care

parental care is carried out by females

folivore

an animal that mainly eats leaves.

food

A substance that provides both nutrients and energy to a living thing.

frugivore

an animal that mainly eats fruit

granivore

an animal that mainly eats seeds

herbivore

An animal that eats mainly plants or parts of plants.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

pheromones

chemicals released into air or water that are detected by and responded to by other animals of the same species

polygynandrous

the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

scent marks

communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them

scrub forest

scrub forests develop in areas that experience dry seasons.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

stores or caches food

places a food item in a special place to be eaten later. Also called "hoarding"

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

year-round breeding

breeding takes place throughout the year

Ref­er­ences

Berquist, P. 2000. "Neotoma Al­bigula" (On-line). Ari­zona-Sonora Desert Mu­seum Dig­i­tal Li­brary. Ac­cessed March 11, 2011 at http://​www.​desertmuseumdigitallibrary.​org/​public/​detail.​php?​id=ASDM05440.

Brown, J. 1968. Adap­ta­tion to en­vi­ron­men­tal tem­per­a­ture in two species of woodrats, Neotoma cinerea and N. al­bigula. Ann Arbor, MI: Uni­ver­sity of Michi­gan.

Cock­rum, E. 1982. Mam­mals of the South­west. Tuc­son, AZ: Uni­ver­sity of Ari­zona Press.

Davis, W. 1960. The Mam­mals of Texas. Austin, TX: The In­for­ma­tion-Ed­u­ca­tion Di­vi­sion of the De­part­ment of Wildlife Man­ag­ment Agri­cul­ture and Me­chan­i­cal Col­lege of Texas.

Hoffmeis­ter, D. 1986. Mam­mals of Ari­zona. Tuc­son, AZ: Uni­ver­sity of Ari­zona Press.

Macedo, R., M. Mares. 1988. "Neotoma Al­bigula" (On-line pdf). Ac­cessed April 04, 2011 at http://​www.​science.​smith.​edu/​departments/​Biology/​VHAYSSEN/​msi/​.

Olsen, R. 1971. "SEC­ONDARY HABI­TAT SE­LEC­TION IN THE WHITE-THROATED WOODRAT (NEOTOMA AL­BIGULA)" (On-line pdf). Ac­cessed March 11, 2011 at http://​proquest.​umi.​com.​proxy.​lib.​umich.​edu/​pqdweb?​did=758221101&​Fmt=7&​clientId=17822&​RQT=309&​VName=PQD&​cfc=1.

Prakash, I., P. Ghosh. 1975. Ro­dents in Desert En­vi­ron­ments. The Hauge: W. Junk.

Zeng, Z., J. Brown. 1989. Com­par­a­tive Pop­u­la­tion Ecol­ogy of Eleven Species of Ro­dents in the Chi­huahuan Desert. Ecol­ogy, 70/5: 1507-1525.

Zevel­off, S. 1988. Mam­mals of the In­ter­moun­tain West. Salt Lake City, UT: Uni­ver­sity of Utah Press.