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Leporillus conditorgreater stick-nest rat

By Alecia Stewart-Malone

Geographic Range

Greater stick-nest rats (Leporillus conditor) once occupied most of the southern arid and semi-arid regions of southern Australia including the local mountain ranges. Though greater stick-nest rats are widely distributed across this region, its distribution is patchy as a result of the patchy distribution of its preferred diet of perennial, semi-succulent shrubs. Between 1860 and 1930, the geographic range of greater stick-nest rats declined drastically due to the die-off of mainland populations of the species. Eventually only two small, isolated populations remained on the East and West Franklin Islands in the Nuyt’s Archipelago off the coast of Southern Australia. In 1860, the first populations disappeared around the area of the Murray-Darling confluence and in the Flinders Ranges region. The die-off then spread, moving from east to west and from south to north. Only 1000 rats on the East and West Franklin Islands are estimated to have survived the 70 year period, limiting the species' current range. (Barclay, et al., 2006; Copley, 1999; Moseby and Bice, 2004)

Habitat

Greater stick-nest rats prefer dune and dune base habitats in which large communal nests are constructed out of interwoven sticks, stones, straw, leaves, flowers, bones, and scats. Among eight rats monitored for eight months during a reintroduction trial within the Roxby Downs Arid Reserve in Australia, shelters were built mostly in dead Umbrella Wattle (Acacia ligulata) or Narrow-leafed Hopbush (Dodonaea viscosa) shrubs covered in low vegetation. The wild population of greater stick-nest rats on the Franklin Islands use dense shrubs as well as Short-tailed shearwater nests (Puffinus tenuriostris) for their nests. In addition to shrubbery, the rats may use rock crevices for shelter. No matter the material used, cover from predators, especially those that hunt prey from the sky, is a important requirement of the rat’s habitat. On the interior of these nests, the rats create chambers lined with fine sticks and stripped bark that form a series of tunnels that radiate from a central chamber. ("Approved Conservation Advice for Leporillus conditor (Greater Stick-nest Rat)", 2003; Copley, 1999; Moseby and Bice, 2004; Pearson, et al., 2001; Robinson, 1975)

Shelters can be built both above and underground, the latter of which typically contain more than one entrance covered with piles of sticks. The above ground shelters measure less than 80 cm in diameter and 50 cm in height. Most of the nest building seems to be done by the adult female. Greater stick-nest rats have also been observed utilizing underground burrows of other species. These large nests are communal and inhabited over multiple successive generations. In captivity, these nests have been documented to house anywhere from 10 to 20 individuals at one time and consist of one adult female, a few of her litters, and usually one adult male. The adult female can often display aggression towards the male, however, in which case the male will often seek shelter away from the main group. While more than one litter may reside in the den at one time, the young generally do not stick around after the next litter is born. If an adult female is seen with an older young, however, it is most likely a female offspring. In some re-introduced populations on offshore islands, female rats may occupy small, relatively stable den areas, while the male rats occupy a wider range of den sites. ("Approved Conservation Advice for Leporillus conditor (Greater Stick-nest Rat)", 2003; Copley, 1999; Moseby and Bice, 2004; Pearson, et al., 2001; Robinson, 1975)

Physical Description

Greater stick-nest rats have fluffy yellowish-brown to grey fur. Their bellies are cream colored and their hind feet have distinctive white markings on the upper surfaces. Greater stick-nest rat bodies are compact and accessorized with large ears and a blunt nose. Their incisors are continually growing, which allows them to consume hard seeds and carry sticks for nest building. Greater stick-nest rats can get up to 26 cm long and weigh up to 450 g. The average weight for both male and female adults is 300 g and the average weight for both male and female sub adults is less than 150 g. ("Approved Conservation Advice for Leporillus conditor (Greater Stick-nest Rat)", 2003; Copley, 1999; Moseby and Bice, 2004)

  • Sexual Dimorphism
  • sexes alike
  • Range mass
    450 (high) g
    15.86 (high) oz
  • Average mass
    300 g
    10.57 oz
  • Range length
    26 (high) cm
    10.24 (high) in

Reproduction

Greater stick-nest rats mate opportunistically. One study monitored eight rats within the Arid Reserve in Roxby Downs, in which all males were frequently seen following and trying to mate with the same single adult female. Little other information exists on the mating systems of greater stick-nest rats; however old world rats and mice tend to have polyandrous mating systems. (Moseby and Bice, 2004)

The litter sizes of greater stick-nest rats greatly depends on whether the individual lives in the wild or in captivity. In the wild, they typically give birth to one to two young, whereas in captivity they have upwards of four. The oestrous cycle is 14 days but seems to be very irregular. Based on data collected from only one male greater stick-nest rat, the testes/body mass percentage is 2.14 g and the sperm length is 91 micrometers. (Breed and Taylor, 2000; Copley, 1999; Wootton, 1987; Yom-Tov, 1985)

  • Breeding interval
    Greater stick-nest rat populations on the Franklin Islands breed year round.
  • Range number of offspring
    4 (high)
  • Average gestation period
    44 days
  • Range weaning age
    30 to 40 days
  • Average age at sexual or reproductive maturity (female)
    8 months
  • Average age at sexual or reproductive maturity (male)
    8 months

Greater stick-nest rat young are born in the nest and are carried around firmly attached to the mother’s teats. The young grow quickly and at two months of age they are up and on their own feet--though they will still get an occasional ride from the mother. As the young grow older, they are carried around less and become more independent. (Copley, 1999)

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

Lifespan/Longevity

Greater stick-nest rats may live up to five years. ("Alice Springs Desert Park", 2011)

  • Range lifespan
    Status: wild
    5 (high) years

Behavior

Little information exists regarding the general behavior of greater stick-nest rats. Much of the current information is based upon the behavior of eight greater stick-nest rats monitored for eight months at the Arid Recovery Reserve. Every male rat’s areas of activity overlapped and most always centered around the same older female’s area of activity. This main female’s shelter was also shared by all the males. The other two resident females were most often found alone, though they were occasionally found together in a pair. Only one of the adult male rats spent any mentionable amount of time with the non-main adult female, but only at night and after she had become sexually mature. Greater stick-nest rats are a relatively sedentary species that are well known for their gentle and placid nature. They are largely nocturnal. ("Arid Recovery", 2012; Copley, 1999; Moseby and Bice, 2004)

Home Range

Based on the eight monitored rats at the Arid Reserve, when greater stick-nest rats ventures out at night, they generally stay within 150 m of their daytime shelter sites. (Moseby and Bice, 2004)

Communication and Perception

Little is known about greater stick-nest rats communications and perceptions.

Food Habits

Greater stick-nest rats residing in captivity have a widely varied diet of foliage, flowers, seeds, and fruits from a diverse range of arid zone plant species. The leaves and shoots of succulent and semi-succulent shrubs seem to be preferred by the animals. Chenopod and other plant species that contain large amounts of water are also strongly preferred. Specifically, rats in captivity mainly consume common perennial dune species such as bladder saltbush (Atriplex vesicaria), ruby saltbush (Enchylaena tomentosa) and Sturt’s pigface (Gunniopsis quadrifida), the latter being the most heavily browsed. Gunniopsis quadrifida and Calandrinia remota are also commonly grazed upon due to their high water content. On the Franklin Islands, the diet of greater stick-nest rats consist almost entirely of leaves and fruits from succulent plants including Rhagodia crassifolia, Nitraria billardierei, Carpobrotus rossii and Tetragonia implexicoma, as well as a small percentage of grasses. (Copley, 1999; Moseby and Bice, 2004; Ryan, et al., 2003)

Greater stick-nest rats are not heavy grazers, typically eating small amounts of tissue from an individual plant at one time, most often at the tips of leaves. In captivity, rats spend much of their time foraging on top of and at the bases of the dunes. They were rarely seen wandering further than 150 m from daytime shelter sites. They most typically forage when they are covered by surrounding brush and normal nocturnal activity was seen in adult males that seemed to be loosely aimed towards foraging efforts. Greater stick-nest rats have been known to be quite resourceful and flexible in their foraging strategies, climbing bushes and pulling down branches to reach the youngest and ripest parts of the plant and rummaging through leaf litter to pick out seeds. (Moseby and Bice, 2004; Ryan, et al., 2003)

  • Plant Foods
  • leaves
  • wood, bark, or stems
  • fruit
  • flowers

Predation

When populations of greater stick-nest rats first began to decline in 1860, it was believed to be due to habitat destruction and the removal of food sources by large flocks of sheep. This was shortly followed by the drought of 1864-65, after which no greater stick-nest rats were recorded within their natural habitat. Though all current populations of greater stick-nest rats are heavily monitored and live in managed habitats, threats to the population still exist. Some of the threats include introduced feral predators, extensive fire, disease, and severe drought, but predation by native predators remains the largest threat. On the Franklin Islands, greater stick-nest rats make up 91% of barn owls' diets and are also heavily predated by black tiger snakes. On St. Peters Island, the main predators include extant population of black tiger snakes and sand goannas. On the mainland, dingos present the largest threat. ("Approved Conservation Advice for Leporillus conditor (Greater Stick-nest Rat)", 2003; Copley, 1999)

Ecosystem Roles

Certain chenopod plant species may become less abundant in the presence of greater stick-nest rats due to their light, but continuous grazing. Also, greater stick-nest rats prefer some female plants to male plants of Atriplex vesicaria) due to a difference in water content, thus skewing the proportion of male to female plants within a population. However, during the eight month monitoring period within the Arid Reserve in Roxby Downs, no plant mortality was observed in any plant species that was grazed upon by the eight resident rats. (Moseby and Bice, 2004; Ryan, et al., 2003)

Economic Importance for Humans: Positive

Greater stick-nest rats are a widely accepted candidate species for studying the genetic changes that occur within reintroduced animal populations. Twelve polymorphic loci have been isolated and characterized from greater stick-nest rats. These loci are being used to widen our understanding of population genetics and, more specifically, the genetic differences between captive and reintroduced populations. The conclusions drawn from studying this candidate species may be applied to explain the genetics of other captive and reintroduced populations. (Barclay, et al., 2006)

  • Positive Impacts
  • research and education

Economic Importance for Humans: Negative

Little is known of the negative economic importance that greater stick-nest rats have to humans.

Conservation Status

Beginning in the mid-1980’s, a captive breeding and reintroduction program was started using the two native populations of greater stick-nest rats on the Franklin Islands. In 1997, 8 rats were reintroduced within the Arid Recovery Reserve north of Roxby Downs in northern South Australia. In April 1999, these same eight rats bred and the trial was considered a success. In addition to the Arid Recovery Reserve in Roxby Downs, reintroduced populations of greater stick-nest rats currently reside on Salutation Island, Heirisson Prong (Western Australia), St. Peter Island, Reevesby Island, Venus Bay Conservation Park (South Australia), and The Scotia Sanctuary (New South Wales). Numerous attempts to reintroduce greater stick-nest rats to their native range on the mainland of Australia have been recorded and failed due to predation by native and introduced predators. Causes thought to have triggered the massive decline of greater stick-nest rat populations include severe drought, habitat destruction from introduced domestic stock and European rabbits, and predation by native and introduced predators (e.g. barn owls, feral cats, and foxes). (Barclay, et al., 2006; Moseby and Bice, 2004; Ryan, et al., 2003)

Existing conservation plans include the Threat Abatement Plan for Predation by European Red Fox and the Arid Recovery Initiative, which facilitates the monitoring and continued research on Greater stick-nest rat populations reintroduced at the reserve in Roxby Downs. ("Arid Recovery", 2012)

Other Comments

Greater stick-nest rats have large ears and a fluffy coat, giving it a rabbit-like appearance leading early European colonists to call it a rabbit-rat. Greater stick-nest rats were once hunted for sport and considered easy prey. Early explorers and native hunters have documented setting the rat’s nests on fire or strategically pulling them apart. As the rats would flee from their nests to escape the attack. Tthey would either be captured by Aborigine dogs or hit with sticks and later eaten. Greater stick-nest rats are the last surviving species from its genus. (Barclay, et al., 2006; Copley, 1999)

Contributors

Alecia Stewart-Malone (author), University of Wisconsin-Stevens Point, Christopher Yahnke (editor), University of Wisconsin-Stevens Point, Laura Podzikowski (editor), Special Projects.

Glossary

Australian

Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.

World Map

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

colonial

used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms.

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.

frugivore

an animal that mainly eats fruit

herbivore

An animal that eats mainly plants or parts of plants.

introduced

referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.

island endemic

animals that live only on an island or set of islands.

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

sexual

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

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

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

2011. "Alice Springs Desert Park" (On-line). Accessed April 28, 2012 at http://www.alicespringsdesertpark.com.au/kids/nature/mammals/nestrat.shtml.

2003. "Approved Conservation Advice for Leporillus conditor (Greater Stick-nest Rat)" (On-line pdf). Accessed January 19, 2012 at http://www.environment.gov.au/biodiversity/threatened/species/pubs/137-conservation-advice.pdf.

2012. "Arid Recovery" (On-line). Accessed January 18, 2012 at http://www.aridrecovery.org.au/index.

Barclay, S., B. Costello, W. Sherwin. 2006. Limited cross-species microsatellite amplification and the isolation and characterization of new microsatellite markers for the greater stick-nest rat (Leporillus conditor). Molecular Ecology Notes, 6: 882-885.

Breed, W., J. Taylor. 2000. Body Mass, Testes Mass, and Sperm Size in Murine Rodents. Journal of Mammalogy, 81: 758-768.

Burbidge, A., M. Williams. 1997. Mammals of Australian Islands: Factors Influencing Species Richness. Journal of Biogeography, 24: 703-715.

Copley, P. 1999. Natural histories of Australia's stick-nest rats, genus Leporillus (Rodentia:Muridae). Wildlife Research, 26: 513-539.

Lomolino, M., R. Channell. 1995. Splendid Isolation: Patterns of Geographic Range Collapse in Endangered Mammals. Journal of Mammalogy, 76: 335-347.

Morton, S. 1979. Diversity of Desert-Dwelling Mammals: A Comparison of Australia and North America. Journal of Mammalogy, 60: 253-264.

Moseby, K., J. Bice. 2004. A trial re-introduction of the Greater Stick-nest Rat (Leporillus conditor) in arid South Australia. Ecological Management & Restoration, 5: 118-124.

Pearson, S., A. Baynes, B. Triggs. 2001. The record of fauna, and accumulating agents of hair and bone, found in middens of stick-nest rats (Genus Leporillus) (Rodentia:Muridae). Wildlife Research, 28: 435-444.

Robinson, A. 1975. The Sticknest Rat, Leporillus conditor, on Franklin Island, Nuyts Archipelago, South Australia. Australian Mammology, 1: 319-327.

Ryan, S., K. Moseby, D. Paton. 2003. Comparative foraging preferences of the Greater Stick-nest Rat Leporillus conditor and the European Rabbit Oryctolagus cuniculus: Implications for regeneration of arid lands. Australian Mammology, 25: 135-146.

Wootton, J. 1987. The Effects of Body Mass, Phylogeny, Habitat, and Trophic Level on Mammalian Age at First Reproduction. Evolution, 41: 732-749.

Yom-Tov, Y. 1985. The Reproductive Rates of Australian Rodents. Oecologia, 66: 250-255.

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