Casuariidae Cassowaries and Emu
Version: 1.0 — Published March 4, 2020
Introduction
The Emu is the pervasive large ground bird of open habitats in Australia, and cassowaries dwarf all other birds in the understory of humid forests in northeastern Australia and New Guinea. As in most others of this order, the males care for the eggs and chicks without any aid from the female. Cassowaries bear a daggerlike claw on their second toes, and both they and Emus can defend their chicks with a kick and a slash. Both groups have bare facial skin that is brightly colored, with cassowaries also sporting a flexible casque on top of the head and colored wattles low on the neck. These birds are also the only ones thought to routinely use infrasound in communication.
Habitat
Emus inhabit open, arid habitats, from grasslands to open woodlands. Cassowaries occupy wetter, denser habitats, from rainforests to savanna woodlands.
Diet and Foraging
Emus are omnivorous, feeding on a variety of plants, including leaves, fruits, seeds, and roots, as well as insects and other invertebrates. Cassowaries are primarily frugivorous and generally eat fruit that has fallen on the ground; however, they occasionally eat insects and small vertebrates.
Breeding
Emus and cassowaries are monogamous to polyandrous, with females mating and laying several clutches with up to several different males. The nests of Emus and cassowaries consist of shallow depressions in the ground that are lined with leaves and grass and are built by males before courting begins. Female Emus lay large clutches of 5 to 15 eggs, whereas female cassowaries lay 3 to 5 eggs per clutch. After a female lays eggs in the male’s nest, it leaves that male in search of another mate. The male incubates the eggs alone for seven to eight weeks and cares for the chicks for up to nine months after hatching, protecting them from predators and showing them sources of food, which the chicks actively take shortly after hatching. Young finally become sexually mature after about one and one-half to two years.
Conservation Status
With a status of least concern, Emus are not currently threatened; however, the three species of cassowaries are currently in decline (1 NT, 2 VU), owing to habitat destruction and degradation, hunting, and predation from introduced mammalian predators such as feral pigs.
Systematics History
Although the relationships of Casuariidae with the other ratites and tinamous have long been controversial, the grouping of Emu and cassowaries as sister lineages within the same family has broad support from studies of disparate morphological and genetic characters (Sibley & Ahlquist 1990, van Tuinen et al. 1998, Hackett et al. 2008, Harshman et al. 2008, Phillips et al. 2010, Livezey & Zusi 2001, 2007). Recent genetic work generally supports a sister relationship with Apterygidae; however, relationships with other struthioniforms cannot be ruled out (Phillips et al. 2010).
Conservation Status
Least Concern |
75%
|
---|---|
Near Threatened |
0%
|
Vulnerable |
0%
|
Endangered |
0%
|
Critically Endangered |
0%
|
Extinct in the Wild |
0%
|
Extinct |
0%
|
Not Evaluated |
0%
|
Data Deficient |
0%
|
Unknown |
25%
|
Data provided by IUCN (2023) Red List. More information