This World Cassowary Day, let us take a deep dive into into the obscurities of the mysterious world of the cassowaries among the rich, dense rainforests, appreciating the dangerous beauty of these notorious birds.

Commonly referred to as cassowaries, these large, flightless birds are considered to be ratites. Their unique name is considered to be of Papuan origin, with “ Kasu ” referring to ‘horned’ and “ weri ” referring to ‘head’, indicating its name of origin to be linked with its distinctive headgear. These aves belonging to the genus Casuarius and the family Casuariidae  are most closely related to the emus, resembling them through their external morphology. Cassowaries can be classified into three main species as Common/ Southern cassowary (Casuarius casuarius), Northern cassowary (Casuarius unappendiculatus) and Dwarf cassowary (Casuarius bennetti).

Regardless of the species specificity, a few common, yet distinctive features can be recognized in these birds that are considered to be native to Northern Australia, New Guinea and the surrounding islands.

Cassowaries are the second heaviest birds in the world, as well as the heaviest birds in Australia. The adult cassowaries possess black hair-like feathers, designed for their safety and protection from sharp thorns in the forests. These feathers consist of a shaft and loose barbules and its’ glossy nature is given by the rachis, that is the spine of the feather, instead of the barbules like in other birds. The cassowary chicks possess brown feathers with black colour streaks.

Two out of the three cassowary species also possess wattles, which are bare, fleshy pouches of skin hanging from the neck. These are brightly coloured including blue, red, gold, white or purple, depending on the species or subspecies. Females are usually more brightly coloured. These unique birds also possess a casque on top of the head. This is made of keratin, and although its function is not yet discovered exactly, scientists assume that it has a function in shedding off heat by the cassowaries. It may also be used for protection in the rainforests, as well as in sound production. Another interesting detail regarding cassowaries is that their call, referred to as the ‘boom’, is the lowest call of any bird and is right at the edge of the human auditory spectrum.

The three main species of cassowaries.

Among the three species of cassowaries, southern cassowary, also known as the double wattled cassowary due to two long red wattles on the throat, is the largest in size. It stands at a height of about 1.5 m,  with the average female weighing around 76kg and average male weighing about 55 kg. Southern cassowaries possess blade-like casque with head, neck and throat being featherless. It is distributed mainly in New Guinea and also in nearby islands and Australia. According to an IUCN assessment in 2018, they have been classified into the ‘Least Concern’ category, with a decreasing population trend.

The northern cassowary, possesses a single wattle on its throat. It also has a larger and more flared casque along with throat skin and wattle of red or golden hues. They are found in New Guinea’s northern lowlands, and is considered to be at highest risk out of the three cassowary species due to its habitat limitation. However, according to a 2017 IUCN assessment, they were categorized as ‘Least Concern’, but with a decreasing population trend.

The smallest cassowary species is the dwarf cassowary, with a height of around 1.1 m and weight of about 29 kg. This particular species lacks wattles and has a round purple spot in place of it. They also have a triangular casque which is flattened at the back. Native to the higher elevated areas of New Guinea and the island of New Britain. It is also classified by IUCN as ‘Least Concern’ based on an assessment in 2016, showing stable population trend.

A southern cassowary with its’ young chick.

“There is no greater anomaly in nature than a bird that cannot fly.”

  • Professor Richard Owen

Despite this obvious disadvantage of being flightless, cassowaries have more than well evolved to protect themselves as a complete land dwelling bird. Famously known as the world’s most dangerous bird, they possess a 3-toed foot having a dagger-like sharp claw of about 10 cm length, on the inner toe, which functions as an excellent weapon for them when attacking or defending itself. Cassowaries are also capable of killing humans in an attack with a blow of its feet, with recorded previous cases of human mortalities due to cassowary attacks. Cassowaries can also run at a speed of about 50 kmph through the dense forest undergrowth and are also known to be excellent at jumping and swimming.

These birds are usually very shy and are known to be solitary creatures, usually only coming together during the breeding season, which falls from May-June to October-November. During a particular breeding season, a single female may breed with more than one male as the male bird is usually charged with parental duties. The nesting site of these birds is generally on the ground with few leaves. Upon successful mating, the female cassowary will lay a clutch of about 3-5 eggs, olive-green in colour. After laying eggs, the female moves on and may breed with another male bird. Meanwhile the male bird incubates the eggs for about 50 days, and later on takes care of the chicks for about 9-10 months. The chicks attain maturity in about 2.5-3 years.

A southern cassowary feeding on a tropical rainforest fruit.

These mesmerizing birds are known to inhabit tropical rainforests and wetlands. In terms of diet, cassowaries are widely called frugivores, and are thus known to feed on fruits. Although they prefer a diet of fallen fruits, they also feed on small vertebrates and invertebrates. Droppings of these birds are known to have partially digested seeds of fruits. In certain cases, passing through the cassowary digestive system is known to increase the chances of germination of certain seeds. For example, germination chances of seeds from the Australian tree Ryparosa sp. is found to increase from 4% to 92% after passing through the cassowary digestive tract.

The southern cassowary scats are known to have a large amount of seeds in them, thus functioning as ready -made fertilizer. The cassowary is also one of the few species that can disperse large rainforest fruits, and is also the only species that is capable of carrying large seeded fruits over long distances. Thus, the importance of the cassowaries as a species is highly significant in protecting and maintaining the rainforest ecosystem, as well as its biodiversity.

A cassowary death near Mission Beach, Australia, in 2022, due to being struck by a car.

However, these fierce feathered creatures face numerous growing threats to their survival, despite many evolutionary protective adaptations to ensure their safety. These include dog attacks threatening cassowary chicks, encroachment of their habitats by pigs, posing competition for food, natural disasters, human interactions, and vehicle strikes. The most significant threat faced by cassowaries is the loss and fragmentation of their habitats, particularly rainforests.

Thus, actions must be taken to ensure the future survival of all these species of cassowaries, especially owing to their role in maintaining the balance and the diversity in the rainforest ecosystems of New Guinea and Australia. These include both ex-situ and in-situ conservation methods such as ensuring their survival within their habitats by reducing risks and threats of dog attacks on the young cassowaries and prevention of encroachment of rainforest habitats by domestic animals like pigs. It can also be done by establishing enclosures and zoos and conservation centers for cassowaries. However, when doing this, care must be taken to provide the birds with required conditions for their survival. For example, as cassowaries are shy, secretive animals, dense undergrowth must be provided in the enclosures as well in order to not cause stress to the birds. However, the most important step that can be taken to ensure the survival of these birds is protection of their habitats.

Cassowary enclosure in the Cairns Tropical Zoo in 2007.

In order to successfully carry out these steps, it is vital for the community to have awareness about these birds. Accordingly, the World Cassowary Day was established in 2014 by conservationist Paul Webster, in order to increase the awareness about cassowaries. Thus, the cassowaries are celebrated every year, on the 26th of September. These birds are celebrated each year in various ways, including festivals on cassowaries, informative sessions, seminars and workshops on cassowary biology and history and workshops to putting up signs to avoid highway accidents of cassowaries. It also includes various workshops and projects on rainforest conservation, ensuring the protection of cassowary habitats and building cassowary rehabilitation centers.

The 2018 Mission Beach Cassowary Festival

Written by:

 Mokshavi Gunasekera

1st Year Undergraduate

Biological Sciences

 Faculty of Science

 University of Colombo

References:

Image Courtesy:

Title Image:

https://www.discoverwildlife.com/animal-facts/birds/facts-about-southern-cassowary

01st Image: https://ca.pinterest.com/pin/153896512258610094/

02nd Image: https://www.ilovecairns.com.au/best-places-cassowaries-cairns

03rd Image: https://birdsoftheworld.org/bow/species/soucas1/cur/introduction

04th Image: https://www.tropicnow.com.au/2022/march/9/another-cassowary-fatality-near-mission-beach-as-wildlife-groups-urge-people-to-stop-feeding-the-birds

05th Image: https://www.zoochat.com/community/media/cairns-tropical-zoo-2007-cassowary-enclosure.78485/

06th Image: https://www.cassowaryconservation.asn.au/world-cassowary-day-events.html


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