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Greater Bilby - Macrotis lagotis
Greater Bilby - Macrotis lagotis

[Image: 640px-Bilby_at_Sydney_Wildlife_World.jpg]

Scientific classification
Kingdom:  Animalia
Phylum:  Chordata
Class:  Mammalia
Infraclass:  Marsupialia
Order:  Peramelemorphia
Family:  Thylacomyidae
Genus:  Macrotis
Species:  Macrotis lagotis  Reid, 1837

The greater bilby (Macrotis lagotis), often referred to simply as the bilby since the lesser bilby (Macrotis leucura) became extinct in the 1950s, is an Australian species of nocturnal omnivorous animal in the order Peramelemorphia. Other vernacular names include dalgyte, pinkie, or rabbit-eared bandicoot. Greater bilbies live in arid areas of central Australia. Their range and population is in decline.

[Image: 220px-Bilby.png]
Distribution of greater bilbies

Once widespread in arid, semi-arid and relatively fertile areas, the bilby is now restricted to arid regions and remains a threatened species. It makes its home in a burrow that spirals down, making it hard for its predators to get in. The bilby prefers arid habitats because of the spinifex grass and the acacia shrubs.

Greater bilbies have the characteristics of long bandicoot muzzle and very long ears. They are about 29–55 centimetres (11–22 in) in length. Compared to bandicoots, they have a longer tail, bigger ears, and softer, silky fur. The size of their ears allows them to have better hearing as well. At 1 to 2.4 kilograms (2.2 to 5.3 lb), the male is about the same size as a rabbit; although male animals in good condition have been known to grow up to 3.7 kilograms (8.2 lb) in captivity. The female is smaller, and weighs around 0.8 to 1.1 kilograms (1.8 to 2.4 lb). Bilbies have an excellent sense of smell and sharp hearing. Their fur is blue-grey with patches of tan and is very soft. The tail is black and white with a distinct crest.
Unlike bandicoots, they are excellent burrowers and build extensive tunnel systems with their strong forelimbs and well-developed claws. A bilby typically makes a number of burrows within its home range, up to about a dozen; and moves between them, using them for shelter both from predators and the heat of the day. The female bilby's pouch faces backwards, which prevents her pouch from getting filled with dirt while she is digging.

Greater bilbies are nocturnal omnivores that do not need to drink water, as they get all the moisture they need from their food, which includes insects and their larvae, seeds, spiders, bulbs, fruit, fungi, and very small animals. Most food is found by digging or scratching in the soil, and using their very long tongues.

In captivity, bilbies typically live for at least five years with some specimens reaching ten years of age. However, wild caught bilbies tend to be less than 12 months old.  Females become reproductively active at six months of age and can breed all year round if conditions are favourable.
Greater bilbies have a very short gestation period of about 12–14 days, one of the shortest among mammals. The young are only 0.25 in (0.6 cm) long and very underdeveloped when they are born. They must crawl to the mother’s pouch and latch onto one of her eight teats. They leave the pouch after 70–75 days and remain in the natal burrow for two to three weeks before becoming independent. Litters usually consist of one to three joeys and females can have up to four litters per year in favourable conditions.

Greater bilbies are generally solitary marsupials; however, there are some cases in which they travel in pairs. These pairs usually consist of two females, and these females are the sole caregivers of their offspring. The female bilby mates iteroparously. Much of the plant diet of the bilby is facilitated by fires that occasionally run through Australian regions and facilitate the regrowth of plants that the bilby prefers. They are also a highly motile species when it comes to foraging, with females traveling on average 1.5 km between burrows and male traveling up to 5 km. The difference in male and female motility is most likely due to the fact that males are often in search of mates and need to only care for themselves, while females are responsible for their offspring and must work to support them. Communication remains difficult between bilbies due to poor eyesight, but since these marsupials usually live alone or in very small groups, this obstacle is not incredibly formidable. Any communication that does occur is mostly olfactory between males or auditory. The scent markings implemented by male bilbies primarily function as a mode of communication between members of the same sex, since female bilbies rarely take heed of such signals and males are never aggressive towards their female counterparts.

Greater bilbies are slowly becoming endangered because of habitat loss and change as well as the competition with other animals. Introduced feral cats and foxes pose a major threat to the bilby's survival, and there is some competition between bilbies and rabbits for food. There is a national recovery plan being developed for saving these animals: this program includes breeding in captivity, monitoring populations, and reestablishing bilbies where they once lived. There have been reasonably successful moves to popularise the bilby as a native alternative to the Easter Bunny by selling chocolate Easter Bilbies (sometimes with a portion of the profits going to bilby protection and research). Reintroduction efforts have also begun, with a successful reintroduction into the Arid Recovery Reserve in South Australia in 2000, and plans underway for a reintroduction into Currawinya National Park in Queensland, with a recent success with six bilbies released into the feral-free sanctuary in early February 2006.
News in The Courier-Mail on 19 July 2012 reporting that the population at Currawinya has been affected by feral cats that gained access into the protected area after the wire netting had rusted after flooding. The high salinity flood water had pooled around sections of the fencing and once parts of it had rusted the cats made their way in through the holes. As of 19 July 2012, no bilbies are said to have been found during an April survey of the area, nor in this current July survey in which the cats have been found.
Successful reintroductions have also occurred onto Peron Peninsula in Western Australia as a part of Western Shield. Successful reintroductions have also occurred on other conservation lands, including islands and the Australian Wildlife Conservancy's Scotia and Yookamurra Sanctuaries. There is a highly successful bilby breeding program at Kanyana Wildlife Rehabilitation Centre, near Perth, Western Australia.
A National Bilby Day is held in Australia on the second Sunday in September to raise funds for conservation projects.

A scientific description of the greater bilby was first published in 1837 by a Mr J. Reid. Reid based his description on a specimen that he erroneously stated to have come from Van Diemen's Land (now Tasmania), where the species has not occurred in historical times. As all bandicoot species were then placed in a broadly circumscribed Perameles, Reid placed the bilby there too. However, noting how different it was from other members of the genus, he added that "should more of the same form be discovered, the above characters would constitute a subgenus to which the name of Macrotis might be applied". The specific epithet lagotis was chosen "from its resemblance to the Rabbit".
The following year, Richard Owen read a paper before the Zoological Society of London, in which he proposed to erect a new genus for this species, named Thylacomys. This name was widely adopted and remained in use for many years. Thus it was that when B. Arthur Bensley erected a subfamily to hold the genus in 1903, he named it Thylacomyinae. This name remains valid, and has since been promoted to family rank as Thylacomyidae, but Thylacomys itself is no longer considered valid, as Reid's original paper is held to have established the generic name Macrotis. Thus the currently accepted scientific name for the species is Macrotis lagotis.
The placement of bilbies within the Peramelemorphia has changed in recent years. Vaughan (1978) and Groves and Flannery (1990) both placed this family within the family Peramelidae. Kirsch et al. (1997) found them to be distinct from the species in Peroryctidae (which is now a subfamily in Peramelidae). McKenna and Bell (1997) also placed it in Peramelidae, but as the sister of Chaeropus in the subfamily Chaeropodinae.

Predator exposure can help vulnerable species survive in the wild

by Isabelle Dubach, University of New South Wales
[Image: predatorexpo.jpg]
A bilby. Credit: Alexandra Ross

Bilbies vs. feral cats—a Hunger Games-style experiment conducted in a South Australian desert has produced fascinating results with important implications for the conservation of our endangered species.
Exposing vulnerable species like the bilby to an environment with predators before releasing them into the wild could help improve the species' ultimate survival, new research by UNSW ecologists has shown.
In their study—published today in the Journal of Applied Ecology—the ecologists compared the behaviour and subsequent survival of two groups of bilbies from different scenarios: a group that had been deliberately exposed to feral cats, and a group that had not come into contact with predators before.
The study is the first experimental test of predator exposure that shows how the fate of animals that are introduced into a predator‐rich environment could be improved by prior experience living with predators.
"Deliberately exposing threatened species to feral cats in a wild setting is risky but our research suggests that it leads to a significant improvement in anti-predator behaviour and survival," says Dr. Katherine Moseby, who initiated the project.
The team—from UNSW, Arid Recovery and UCLA—conducted the experiment in the Arid Recovery Reserve—a 123 km2network of fenced exclosures in arid South Australia. Several locally extinct species have recently been re‐introduced into the Reserve, including the vulnerable greater bilby. In 2016, the Reserve had a population of about 500 bilbies.
"The reserve is divided into paddocks, and we conducted the experiment in three paddocks: the predator‐free paddock, the predator‐exposed paddock, and the release site," says lead author Aly Ross, a Ph.D. candidate at the Centre for Ecosystem Science at UNSW.
Bilbies from the predator-exposed paddock had been living with five feral cats in the 2 years leading up to the experiment, while bilbies from the predator-free environment had never encountered cats or other predators.
"First, we compared the behaviour of bilbies from the predator‐free and predator‐exposed populations in a small fenced pen of a bit over 50 m2 – primarily to see how they'd react to a new environment," says Ms Ross.
The team found that the behaviour of the animals that had previous predator exposure differed from the predator 'novices'.
"Animals that had lived in an environment with predators moved less and sought cover more quickly," says Ms Ross.
"This shows that they were warier of potential threats, whereas the predator-free group of bilbies showed fewer signs of predator awareness."
The fact that animal behaviour can be changed by predator training has been demonstrated before—it's what the group found next that is particularly interesting.
"In a second experiment, we released bilbies from the predator-exposed paddock and some from the predator-free paddock into a third paddock with some feral cats," says Ms Ross.
"Unfortunately, we found that 71 percent of the predator‐free bilbies died in the week after release, but only 33 percent of the predator‐exposed bilbies met the same fate—showing that the bilbies who had been exposed to the very real threat of predators already had benefitted from that experience."

Implications for conservation

The findings have important implications for the conservation of native animals and programs that seek to reintroduce species like the bilby.
"Our native animals did not evolve with introduced cats and foxes," says lead author Dr. Katherine Moseby.
"Isolating threatened animals from introduced predators on islands or inside fenced reserves exacerbates the issue of prey naivety. We are advocating for a different approach whereby threatened species are exposed to these predators in the wild under controlled conditions."
The research provides evidence that predator exposure improves survival in the first 40 days following translocation, and thus that in situ predator training may give predator-naïve species a vital edge that increases the chance of creating a sustainable population in areas with some predators.
"Our research shows that it is possible to make 'better' prey species, because ultimately if native animals are to survive in the wild they need to be able to tolerate the threat posed by introduced predators," says co-author Professor Mike Letnic.
Katherine Moseby agrees: "Although it may take decades or even centuries for our native species to develop the skills they need to combat feral cats and foxes, we need to be working towards that co-existence now."
The greater bilby is a nocturnal marsupial native that once roamed over 70 percent of the Australian mainland. Today, the bilby is listed as vulnerable globally and nationally, with predators—mainly feral cats and foxes—thought to be largely responsible for their continuing decline. With advances in conservation research, including live predator exposure, they just might bounce back from the brink.

Journal Reference:
Alexandra K. Ross et al. Reversing the effects of evolutionary prey naiveté through controlled predator exposure, Journal of Applied Ecology (2019). DOI: 10.1111/1365-2664.13406

  1. Inappropriate anti‐predator responses (naiveté) towards introduced predators is a key factor contributing to the extinction and endangerment of prey species world‐wide and the failure of wildlife reintroductions. Here, we test the idea that success of reintroduction can be improved by exposing a predator naïve prey species to introduced predators under controlled conditions (in situ predation) prior to reintroduction, such that prey adopt increased wary behaviours to aid in survival.
  2. We exposed a population of a naïve marsupial, the greater bilby (Macrotis lagotis), to a controlled number of introduced predators (feral cats, Felis catus) for 2 years within a large fenced paddock and then compared the pre‐release behaviour and post‐translocation survival of predator‐exposed and predator‐naïve bilbies over 40 days.
  3. Behavioural assays conducted in a small pen prior to reintroduction suggested that predator‐exposed bilbies were warier as they spent less time moving and more time in cover than predator naïve bilbies.
  4. After translocation, predator‐exposed bilbies were more likely to survive to 40 days and were less likely to be preyed upon by cats than predator‐free bilbies.
  5. Synthesis and applications. Naiveté towards predators is a major problem thwarting successful reintroductions world‐wide. Our study demonstrates that exposure to predators under controlled conditions can increase survival of reintroduced prey and is a promising approach to overcome the problem of naiveté towards introduced predators and the global problem of prey naiveté. Future conservation of naïve prey species may depend on such training methods prior to releasing into areas where predators are present.
[Image: wildcat10-CougarHuntingDeer.jpg]
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