Nabarleks have teeth like a shark, with new molars continuously emerging from the back.
Nabarlek Scientific Classification
- Scientific Name
- Petrogale concinna
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Nabarlek Conservation Status
- Name Of Young
- Group Behavior
- Fun Fact
- Nabarleks have teeth like a shark, with new molars continuously emerging from the back.
- Estimated Population Size
- Between 5,000 and 10,000 mature individuals
- Biggest Threat
- Possibly feral cats
- Most Distinctive Feature
- Very small size
- Distinctive Feature
- Bushier tail and longer ears than rock-wallabies of similar size
- Other Name(s)
- Pygmy rock-wallaby, Little rock-wallaby
- Gestation Period
- 30 days
- Age Of Independence
- 175 days
- Litter Size
- Rocky slopes with boulders, caves and crevices, near grass, sedge or ferns for foraging
- Feral cats
- Average Litter Size
- Favorite Food
- grasses, sedges, ferns
- Common Name
- Nabarlek, pygmy rock-wallaby, little rock-wallaby
- Special Features
- Teeth that are continually replaced; red-tinged fur; black markings; black, fluffy tip of tail; ears longer than similar species
- Number Of Species
- Northwest coast of the Kimberley region of Western Australia and the northern part of the Arnhem Land region of the Northern Territory in Australia
Nabarlek Physical Characteristics
- Skin Type
- 17 years
- 2.65 to 3.53 pounds
- 12.2 to 14.4 inches
- Age of Weaning
- Around 175 days
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Nabarleks have teeth like a shark, with new molars continuously emerging from the back!
The nabarlek, also known as the pygmy rock-wallaby or little rock-wallaby, is a tiny member of the Macropodidae family. It is a relative of kangaroos, wallabies, tree-kangaroos, quokkas, and several other marsupial species native to Australia. Nabarleks are an endangered species, native to only a couple of small areas in northwestern Australia. They are at risk due to fires, competition for food, and predation by a destructive introduced species, the feral cat. Nabarleks are incredibly secretive, spending most of their time hidden in caves and crevices on steep, rocky slopes. They come out mostly at night, and they forage on grasses, sedges and tough ferns. These ferns wear down their teeth quickly, but that’s okay, because they continually produce new molars, a lot like sharks!
Incredible Nabarlek Facts
- Nabarleks only grow to be a little over a foot long, not including their tail.
- One subspecies is known from only a single specimen collected nearly 200 years ago.
- Females can get pregnant again right after giving birth and put their new embryo on pause.
- Island subpopulations are more secure than those on the mainland, because there are no cats.
- Nabarleks can eat ferns that contain more than 25 percent silica.
- Aboriginal Australians have hunted nabarleks for food for generations.
Where to Find Nabarleks
Nabarleks are native to a couple of areas in the far northern part of Australia. One subspecies, P. concinna canescens, lives in the Arnhem Land region of the Northern Territory and in the Kakadu National Park. The subspecies, P. concinna monastria lives along the northwestern coast of the Kimberley region of Western Australia, including a handful of small offshore islands. It is unknown whether the third subspecies, P. concinna concinna, still exists, but it was once found in the Top End region of the Northern Territory.
The nabarlek lives on rocky terrain, primarily sandstone or granite. It sticks to areas with steep slopes like rocky hills, cliffs and gorges. It prefers areas with plenty of good places to hide, such as caves and crevices or large boulders. Nabarleks live on the mainland of Australia as well as a few small, rocky islands not far from the shore. They do forage a considerable distance away from the safety of their rocky homes, in grassy areas or among sedges.
Nabarlek Scientific Name
The common name “nabarlek” is an Australian Aboriginal word that comes from the Kunwinjku dialect of the Bininj Kunwok language. The nabarlek is also known as the pygmy rock-wallaby or the little rock-wallaby. Its scientific name is Petrogale concinna. The genus, Petrogale, was established in 1837 by esteemed British zoologist John Edward Gray. It contains the rock wallabies. The specific name, concinna, is a Latin term meaning pretty.
The original named subspecies, P. concinna concinna, is known only from a single specimen that was collected in 1839 and described by John Gould in 1842. Two additional subspecies, P. concinna canescens and P. concinna monastria were identified later.
Nabarleks are tiny marsupials from the Macropodidae family, which includes kangaroos, wallabies, tree-kangaroos, quokkas and several other species. They are one of the smallest species of rock-wallabies. Nabarleks grow to a length of 12.2 to 14.4 inches, not including their long tails. They weigh a mere 2.65 to 3.53 pounds.
Depending on the subspecies, nabarleks may be a little darker or lighter in color. They have soft, light gray fur with a marbled appearance and black markings. Their back is tinged red. Their fur is short and silky over most of their body, except the tip of the tail. There the black fur grows longer, giving it a bushy appearance. Nabarleks hold their tails high, arched up and over their bodies, when they jump.
Nabarleks have large hind feet that they use together on land and separately in the water. The thick soles of the nabarlek’s feet are granulated. This helps it to grip the rocky surfaces where it spends most of its life.
The nabarlek is difficult to distinguish from similar species in the field. It is most closely related to two other tiny rock-wallabies: the short-eared rock-wallaby, Petrogale brachyotis, and the monjon, Petrogale burbidgei.
If there was just one word to describe the behavior of nabarleks, it would be secretive. These little marsupials are mostly nocturnal, and they spend much of their time hiding among rocks. They avoid traps and listen carefully for approaching danger. Juveniles are rarely seen.
Although nabarleks are generally nocturnal, they spend more time outside during the day in the rainy season. At that time, they can be found foraging in the morning and at dusk, and outside their caves even in the middle of the day.
Individuals are most at risk when they venture away from the safety of the rocks to forage. They sometimes wander hundreds of meters away from the rocky hillsides in search of grasses and sedges. When they go out into the open, grassy areas they are easy prey for feral cats.
The nabarlek is an herbivore. It eats grasses and sedges, and according to indigenous people from the area, it also eats fruits and digs for yams. Nabarleks also eat a lot of ferns. Few animals are able to eat the tough and abrasive fronds of ferns, but nabarleks have an advantage. They are one of only five known mammalian species that have continuously emerging teeth, much like a shark.
Throughout a nabarlek’s life, it keeps producing new molars which emerge from the back of its mouth. As its old teeth are worn down from chewing tough ferns, the new molars push forward. They are termed, “marching molars,” because new teeth, up to 80 in each row, just keep marching forward as the old ones wear away.
Male nabarleks reach maturity by two years of age, with females maturing by around 14 months. Pairs produce one offspring at a time, called a joey. Gestation lasts 30 days, after which the joey stays in its mother’s pouch for about 160 days.
Female nabarleks can be extremely aggressive. In captivity they have mauled and even killed males after mating. Females also wean their young quickly and aggressively, in the span of about two weeks. Other rock-wallabies typically allow their young to stay close for three to six months after leaving the pouch.
Nabarleks can breed year-round. Females undergo a postpartum estrous period, meaning they are fertile right after giving birth. If impregnated at that time, they can essentially pause the growth of their next embryo until the current joey leaves the pouch. As soon as it is removed, gestation resumes, and the female gives birth to a new joey within about two weeks. She will sometimes have overlapping offspring at the breast, one in the pouch and the other at foot, before the older joey is fully independent.
Predators & Threats
Feral cats, an introduced species in Australia, are the main predators of nabarleks. Pythons and eagles are also known predators of these small mammals. Predators such as foxes and dingoes do not live in the areas that the nabarlek inhabits, so they are not a threat to the species at this time.
The indigenous Bininj people also hunt nabarleks, traditionally with spears but more recently with firearms. They report sometimes using fire to flush the animals out during a hunt.
Fire is a serious threat to nabarleks. As fires have increased in number and intensity, the nabarlek populations have declined. This may be due in large part to the destruction of nearby food sources.
Another threat to the nabarlek comes in the form of competition for food sources and habitat degradation by grazing animals such as cattle. As food becomes more scarce, the nabarlek has to venture farther and farther from safety.
Lifespan of the Nabarlek
Nabarleks live around 11.7 years on average, but some have reached the age of 17. The IUCN Red List of Threatened Species lists the nabarlek as an endangered species. The most recent assessment, done in 2014, estimated the nabarlek population between 5,000 and 10,000 mature individuals. Although hard data on the elusive species is scarce, the population is thought to be rapidly declining. Only the island subpopulations are believed to be secure at this time. Keeping the nabarlek safe depends largely on preventing the introduction of feral cats to those environments.
- Kangaroo – This large marsupial can jump more than 30 feet in a single bound.
- Tree Kangaroo – This member of the Macropodidae family is the only type that lives in trees.
- Quokka – Short, round, and always ready with a smile, this member of the Macropodidae family is a social media star.
Nabarlek FAQs (Frequently Asked Questions)
What does the nabarlek look like?
Nabarleks look sort of like tiny kangaroos. Their fur is soft and short, and marbled gray with black markings and a tinge of red. They have large hind feet with thick soles that are granulated to help them grip rocky surfaces. Their tail is long, and the tip is black and bushy. They hold their tail up and arched over their back while hopping. This is one way they can be differentiated from the similar short-eared rock-wallaby that shares the same territory.
How big is the nabarlek?
The nabarlek is very small. It is one of the smallest of the rock-wallabies, growing to only about one foot in length, not including its tail. It averages between 2.65 and 3.53 pounds.
When is the nabarlek most active?
Nabarleks are mostly nocturnal, although they do spend time out foraging during the day, mostly at dawn and dusk, in the rainy season.
Are nabarleks easy to find?
Nabarleks are difficult to find, partly because they are primarily nocturnal, but mostly because they hide in difficult terrain, making their homes in caves and crevices on steep, rocky cliffs and hills.
How many varieties of nabarleks exist?
Three subspecies of nabarleks have been described. The first was Petrogale concinna concinna, described in 1842 from a single specimen collected in 1839. It is not known whether this subspecies still exists. Petrogale concinna canescens, from Australia’s Northern Territory, and Petrogale concinna monastria, from Western Australia, are the other two subspecies.
What are the nabarlek's closest relatives?
The nabarlek is most closely related to two other rock-wallabies, the monjon and the short-eared rock-wallaby.
What makes the nabarlek special?
They are one of only five known mammalian species that have continuously emerging teeth, much like a shark. As its old teeth are worn down from chewing tough ferns, new molars emerge from the back and push forward. They are termed, “marching molars,” because new teeth, up to 80 in each row, just keep marching forward as the old ones wear away.
Where did the nabarlek get its name?
The nabarlek got its name from Aboriginal Australians. It is a word from the Kunwinjku dialect of the Bininj Kunwok language.
What other name is the nabarlek known by?
The nabarlek is also known as the pygmy rock-wallaby or the little rock-wallaby. Its scientific name is Petrogale concinna.
Where do nabarleks live?
The nabarlek is found in far northwestern Australia, in the Arnhem Land and Kakadu National Park areas of the Northern Territory and in the rocky coastal areas of the Kimberley region of Western Australia and a handful of small, offshore islands.
Do nabarleks migrate?
Nabarleks do not migrate. They stay in a few very small areas in the northwestern part of Australia, mostly confined to steep, rocky, sandstone or granite formations.
What do nabarleks eat?
Nabarleks eat grasses, sedges, and really tough ferns. They are among the very few animals that can eat such ferns, because of their specially adapted teeth. Nabarleks may also eat fruits and yams, according to indigenous people from the area.
What is a baby nabarlek called?
A baby nabarlek is called a joey.
How many offspring does the nabarlek have?
Nabarleks can breed year-round, but they only have one joey at a time. Sometimes a female nabarlek will produce a new offspring before the older one is completely independent.
When do nabarlek joeys leave the pouch?
Nabarlek joeys stay in their mother’s pouch for about 160 days. After that they stay close by for about two weeks, until they are aggressively weaned and achieve independence. This is unusual among rock-wallabies. Most allow their offspring to stay close for months after leaving the pouch.
Are nabarleks aggressive?
Female nabarleks are aggressive in captivity. They have been known to maul and even kill males after mating. It is unknown whether they are so vicious in the wild.
What predators eat nabarleks?
Feral cats, an introduced species in Australia, are the primary predators of nabarleks. Pythons and eagles have also been known to prey on these small macropods.
What other threats do nabarleks face?
Fires, which have increased in number and intensity, are a severe threat to nabarlek populations. Habitat degradation, due in large part to competition from grazing animals like cattle, also takes a toll. Nabarleks have also been hunted for meat in small numbers by indigenous people in the area for generations.
How long do nabarleks live?
Nabarleks have lived to the age of 17, but the average age is around 11.7 years.
Are nabarleks rare?
Nabarleks are rare. Their most recent estimated population, assessed in 2014 by the IUCN Red List of Threatened Species, was between 5,000 and 10,000 and declining rapidly. But due to the elusive nature of this species, its true numbers are not known. The only subpopulations thought to be secure are the ones on offshore islands.
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- Sue Churchill, Available here: https://www.researchgate.net/publication/323644049
- Wendy R. Telfer and Murray J. Garde, Available here: https://www.jstor.org/stable/27654126
- Alison Ballance, Available here: https://www.rnz.co.nz/national/programmes/ourchangingworld/audio/2018642025/wallaby-vs-shark-a-toothy-quirk-of-nature
- Stephanie Todd, Available here: https://library.dbca.wa.gov.au/static/FullTextFiles/926546.pdf
- IUCN Red List, Available here: https://www.iucnredlist.org/species/16761/21955087#assessment-information