Cassowary

Originally published in The Manitoban, February 2, 2012

Zoological Investigations: Cassowary

The cassowary is a large flightless bird that along with ostriches, emus. kiwis, and rheas is a proud member of the ratite group. The term ratite refers to the shape of the breastbone or sternum; these birds are flightless because the sternum lacks a keel, the site for flight muscle attachment.

There are three species of cassowary: the northern cassowary, Casuarius unappendiculatus, the dwarf cassowary, C. bennetti; and the southern cassowary, C. casuarius johnsonii, (a.k.a. the double-wattled cassowary). All are found in different regions of New Guinea, but only the southern cassowary can be found in Australia. This article will focus on the southern cassowary, mostly so I can type the word 'double-wattle' a lot.

So picture an ostrich, but with shaggy-looking black feathers, a bald blue neck with bright red 'wattles' (flaps of skin) hanging off each side, and a bald, bluish coloured head with a big, brownish thing that looks like a blade-shaped crest or flattened horn on top. This thing is called a 'casque' and it is pretty awesome and mysterious.

The outer layer of the casque is made of keratin (the stuff of fingernails), while the inner portion is made of an odd, foam-like cellular material. The best guess going regarding the function of the casque is that it is used for protection. When cassowaries run through the rainforested jungle, they stretch out their necks and really give 'er. Cassowaries can reach speeds of up to 50km/hr and the resilience of the casque, along with its elastic properties, are believed to efficiently absorb the shocks of getting whipped in the head with branches and occasionally running head-long into trees.

The cassowary's feathers appear shaggy because their structure differs from that of birds capable of flight. They do not have tail feathers or the uropygial (preen) gland used by other birds to keep the feathers clean, water resistant, and their bodies well insulated. The flight feathers are reduced to only five or six elongated, quill-shaped feathers that apparently help protect the birds while they are running madly through the bushes.

The double-wattled cassowary is the second heaviest bird in the world; weighing in at up to 128 pounds, only ostriches are heavier! The double-wattle also has the honour of being the third-tallest bird in the world. Yet another impressive cassowarian feature is the double-wattle's ability to jump up to five feet high in the air. They are terrifyingly strong, with long and powerful legs equipped with huge claws up to 10 centimetres long. The cassowary is not afraid to run full tilt at a potential predator and kick and slice its body right open. There are reports that humans and dogs alike have died as a result of the double-wattle's cutting blow.

Cassowaries, like me, usually like to hang out on their own; except, like me, during the mating season. At such times, they will tolerate the company of another cassowary for awhile, at which point they do what a cassowary must to keep the species alive. This is important because cassowaries are endangered. 

The double-wattled cassowary is listed by the government of Australia as endangered under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act). It was estimated in 2001 that fewer than 1500 individuals remain alive in the wild, making these guys rarer than giant pandas in China. As usual, habitat loss due to deforestation; development; and urbanization are mostly to blame. Vehicular traffic, dogs, and wild pigs are also responsible for cassowarian decline, as are humans that attempt to feed the double-wattles. A tamed double-wattle makes an easy target for cars, dogs, and pigs alike.

Female cassowaries mate with one male, lay eggs in his nest, and then leave in search of other males and other nests in which to lay their eggs. The males incubate the eggs and care for the chicks, which stay with him for between nine and 18 months.

Cassowaries are basically the coolest, and for so many reasons! In addition to being the second heaviest and third tallest bird in the world, really fast, really strong, really weird looking, great swimmers, and the possessor of a not-so common breeding system, cassowaries are also considered a keystone species. Basically, this means they play an crucial role in their ecosystem, even though they are not the most populous species within that ecosystem. Without the cassowary, many other organisms would suffer or die out completely.

Cassowaries are primarily frugivorous, which is fancy-talk for fruit-eating, and many plant species can not germinate unless they have first passed through the digestive tract of a cassowary. Their digestive tract is short, so food passes rapidly through the system, and hence ingested seeds are not destroyed. This partial digestion removes the tough, protective seed coat and speeds the process of germination of those seeds. Currently, up to 70 plant species have been identified which have seeds so large that no other animals can eat them. The cassowaries, by eating seeds from these plants, help disperse those seeds far and wide, increasing the likelihood those plants will survive and reproduce. As if that wasn't enough, another 80 plant species have been found which are toxic, and only the cassowary, with their rapid-acting digestive system, can consume them without harm. Again, this is crucial for the dispersal of these toxic plants. 

 

I bet you there are some pretty crazy videos on the internet where you can watch a double-wattled cassowary run and kick some stuff with it's huge, powerfully clawed feet. Just sayin'. 

Southern Cassowary with young.