The Forrest's mouse, or desert short-tailed mouse, is a small species of rodent in the family Muridae. It is a widespread but sparsely distributed species found across arid and semi-arid inland Australia, commonly found in tussock grassland, chenopod shrubland, and mulga or savannah woodlands.
Description
The Forrest's mouse is a small mouse weighing between 15-25g, but recorded to 30g. Short, thick tail that is distinctly less than of the combined head and body length. Body is thickset with a broad, blunt muzzle, and relatively small ears and eyes. Upperparts are a thick, lustrous and short fur of pale yellow brown or greyish fawn, with a pencilling of darker hairs, and small white patches behind the ears. There is a strong demarcation to white under the lower jaw, chin and feet, with the sparsely haired tail grey above and pale grey below, and the ears rounded and pinkish-grey.
Taxonomy
first identified Leggadina forresti in 1906 from a specimen collected at Alexandria Station in the Northern Territory. The genus Leggadina contains two species, both found in Australia including Leggadina forresti and the tropical short-tailed mouse, or Lakeland Downs mouseLeggadina lakedownensis, which is found in moist tussock grassland and tropical savannah of coastal northern Australia. Several synonyms exist for this species:
A nocturnal and terrestrial animal, the Forrest's mouse shelters during the day in a grass nest in shallow burrows, and also in cracks in the soil. Although little is known on the population dynamics and social organisation of the species, it is thought they are a solitary animal, occurring in low densities regardless of habitat suitability. Individuals have been recorded entering a state of torpor in both captivity and the wild, and longevity is estimated to be 1.5 to 2 years. Habitats are varied and include: riparian Coolabah forest, tussock grassland, stony saltbush plains, mulga and savannah woodlands, chenopod shrubland and sandy ridges, and cracking clay pans.
Reproduction
The reproductive rate of Forrest's mouse peaks during winter and spring, with some breeding occurring in autumn, and thought to be related to rainfall. Litter size is usually of 3 to 4 young, with a gestation period of 35 days, and a weaning period of 28 days, when the young reach around 9g in weight. It is unclear as to the age at which individuals reach sexual maturity.
Diet
The Forrest's mouse has a varied diet, and is considered an omnivore. Food items identified include seeds, green plant stems and leaves, arthropods including beetles and spiders, and fungi. Assessment of stomach contents concluded the major food item was seed, followed by arthropods at 27%, with the remainder consisting ofstem and leaf material. It is generally thought that the Forrest's mouse does not rely on standing water for drinking, as it obtains sufficient moisture from its diet in a similar fashion to other well adapted desert rodents.
Predators
The Forrest's mouse is subject to predation by both introduced animals and native predators. Both feral cats Felus catus and the European red foxVulpes vulpes have been recorded as preying on the Forrest's mouse in Queensland, which has been identified as a contributing factor in the decline of native rodents. The barn owlTyto alba is known to prey on the species in South Australia, and other birds of prey recorded consuming the Forrest's mouse include the letter-winged kiteElanus scriptus in the Simpson Desert. In assessing the risk of dingoCanis lupus dingo predation to threatened vertebrates in western NSW after re-introduction, it was found that the Forrest's mouse faced a high risk of predation from dingoes, based on bodyweight, behaviour and habitat.
Threats
Heavy grazing and the trampling of habitat by domestic stock, feral goats, rabbits and pigs has been identified as a threat to the Forrest's mouse. Grazing by stock affects native rodents through the removal of shrubs and grasses that provide food and shelter, and powder and compact the topsoil, which makes burrowing difficult or impossible. This can also make the Forrest's mouse more vulnerable to predation, and reduces the ability to move between isolated habitats. Predation by feral cats and foxes is considered a threat to the Forrest's mouse, and exotic species such as the house mouse Mus domesticus have the ability to sustain the population of predators. The house mouse, along with other introduced herbivores compete with the Forrest's mouse for food resources and habitat. The loss of habitat through inappropriate or altered fire regimes is recognised as a threatening process for native rodents, however it is unclear as to whether the Forrest's mouse is adversely affected by current fire regimes, or what requirements are needed in terms of fire history. The use of 1080 poison in pest control has the potential to poison the Forrest's mouse through the ingestion of baits, and the use of pesticides for the control of locusts may also represent a threat. The introduction of standing water through farm dams and irrigation schemes has the potential to attract potential predators and competitors of the Forrest's mouse, and serve as focal point for herbivores and the modification of vegetation through grazing. A loss of habitat through the clearing of trees, shrubs and grasses, the removal of ground debris and loss of hollows have also been identified as a threat to the survival of the Forrest's mouse.
