The eastern quoll (Dasyurus viverrinus) is a small spotted marsupial predator that once lived across southeastern Australia and now survives mainly in Tasmania, with reintroduced populations in fenced sanctuaries on the mainland. It occurs in two natural color forms, fawn and black, both covered in white spots.

The black morph is found across Tasmania and can be locally common in some regions, although the fawn morph is generally more widespread and makes up roughly 75% of the population. The relative abundance of black and fawn morphs varies across different parts of Tasmania.

Adults are about the size of a small cat. Males reach head and body lengths of 35 to 45 centimeters (14 to 18 inches), with tails measuring 20 to 28 centimeters (8 to 11 inches), and most weigh between 1.1 and 1.3 kilograms (2.4 to 2.9 pounds). Females are smaller, typically weighing 600 to 1,030 grams (1.3 to 2.3 pounds).

One way to distinguish this species from Australia’s other quolls is by the hind feet, which have four toes instead of five. The tail is unspotted, the snout is narrow and pointed, and the upright ears give it a sharp, alert look.

Eastern quolls hunt alone and are most active at night. They move through grassland and open woodland using sharp hearing and smell to take large insects, small mammals, birds, and occasional reptiles, and they scavenge when food is available. During the day, they rest in hollow logs, burrows, or rocky crevices and shift between several dens over a season.

Typical home ranges of about 35 hectares for females and about 44 hectares for males, which are roughly 86 acres and 109 acres. GPS tracking shows that they are strongly nocturnal, although a few individuals make short daytime movements.

Breeding happens once a year as the weather begins to cool. After a very short pregnancy of about 20 to 24 days, the tiny newborns make their way into the mother’s pouch. She often gives birth to more young than she can support, and only the ones that manage to attach to a teat survive, usually around six.

They stay in the pouch for roughly eight to twelve weeks before the family shifts to a grass-lined den. Weaning happens at around 18 weeks, and by the time they are 10 to 11 months old, they are ready to breed themselves. In the wild, most eastern quolls live only 3 to 4 years, although one captive individual reached about 6.8 years.

Eastern quolls once lived across parts of mainland Australia, but they disappeared during the twentieth century. Foxes were introduced earlier, feral cats spread later, and both hunted quolls or outcompeted them. At the same time, changes to farmland and bushland reduced the safe places they depended on. By the time biologists understood how quickly numbers were falling, the species had already vanished from the mainland.

Today, the eastern quoll is listed as Endangered under Australia’s national law and on the IUCN Red List. In Tasmania, where they still survive, feral cats remain the strongest pressure, with habitat change and road collisions adding further strain.

Conservation work focuses on keeping cat numbers low, protecting ground cover and den sites, and improving nighttime visibility on roads. Strong Tasmanian devil populations help as well because devils disrupt cats and shift the balance in favor of smaller native predators.

Scientists have long known that the black morph of the eastern quoll is a form of melanism, which means the animal produces more dark pigment than usual and ends up with a black coat. What they did not know until recently was what exactly causes this extra pigment in this species.

New research has found that an important part of the answer lies in a gene called ASIP, short for Agouti Signaling Protein. In a typical quoll, this gene helps the fur produce lighter colors by controlling how pigment is made. In black morph eastern quolls, a piece of the ASIP gene is missing, so it no longer works properly.

Because ASIP is disrupted, the fur produces much more dark pigment and far less of the lighter tones. This genetic change in a single pigment gene plays a major role in creating the black coats seen in some eastern quolls.

Researchers are now looking at where this gene change appears across Tasmania and whether black and fawn quolls use their surroundings in slightly different ways. The science is still new, but learning how the two color forms behave in the landscape may help explain why black quolls are more common in some regions than others.