The bilby population has significantly decreased over the past 200 years due to habitat loss, disease, vehicular collision, and invasive species that prey on the bilbies and overgraze their habitat’s vegetation.
While native species, such as carpet pythons (Morelia spilota), monitor lizards (Varanidae), and some raptors (Accipitridae) are potential predators of bilbies, the most common and destructive predators are introduced species.
Non-native species that prey on bilbies include dingos (Canis lupus dingo), red foxes (Vulpes vulpes), and feral cats (Felis catus). Dingos were thought to have been introduced in Australia about 3,500 years ago. Red foxes were brought to Australia for the purpose of recreational hunting in 1855 by European settlers. Within 100 years of their introduction, red foxes spread across continental Australia and currently inhabits all regions of the continent with the exception of the tropical northern region of Australia. Domestic cats were originally released throughout Australia around 1855 to control the population of another invasive species, European rabbits (Oryctolagus cuniculus), as well as mice and rat populations. Domestic cats quickly expanded over the entire continent of Australia, killing many native species.
Like the yallara, or lesser bilby (Macrotis leucura), bilbies, also known as greater bilbies, have suffered a significant drop in population over the past 200 years due to the introduction of invasive predators such as dingos (Canis lupus dingo), red foxes (Vulpes vulpes), and feral cats (Felis catus), and invasive herbivores such as European rabbits (Oryctolagus cuniculus). The introduction of both European rabbits (Oryctolagus cuniculus) and livestock has greatly reduced the abundance of grasses, seeds, and other plant matter typically fed upon by native bilbies. As well as the reduction of plants through feeding, grazing has also led to the degradation of bilby habitat. Bilby habitat is also being destroyed as a result of human development and they are hit by cars along roads.
Along with the introduction of invasive species, a number of new diseases have also been brought to Australia. Bilbies are highly susceptible to the parasites and diseases of introduced animals and are commonly infected when they come into contact with feces of introduced species while digging. Without immunities to fight these parasites and diseases, many die as a result.
• Image | ©️ Julie Burgher, Some Rights Reserved, (CC BY-NC 2.0)
• Sources | (Burbidge & Woinarski, 2016; Commonwealth of Australia, 2010, 2015; Environment Australia, 2004; Hintze, 2002; Parks and Wildlife Commission of the Northern Territory, 1998; Pavey, 2006; Tydale-Bicsoe, 1973)