Southern Cassowary
Photo © Tyrone Lavery
November 10, 2015 Birds No Comments

(Casuarius casuarius johnsonii)

Southern Cassowary Photo © Tyrone Lavery

Southern Cassowary
Photo © Tyrone Lavery

The southern cassowary, also known as the double-wattled cassowary (family Casuariidae), is native to the tropical forests of New Guinea, nearby islands and north-eastern Australia. The name cassowary comes from the Malay name kesuari. The cassowary is the largest fruit-eating bird in the world.

The cassowary forms part of a group known as ratites – large, flightless birds – also including the emu, rhea, kiwis and ostrich. There are three species of cassowary: dwarf or Bennett’s cassowary (C. bennettii, with two subspecies); northern or single-wattled cassowary (C. unappendiculatus), both found in New Guinea; and the southern cassowary, the only one found in New Guinea and Australia.

Description

Adult cassowaries are striking in appearance, with a tall brown casque (helmet) on top of their head, a vibrant blue and purple neck, red wattles and glossy black plumage. The purpose of the casque is unknown and hypotheses include that it indicates dominance, protects the bird’s head when running through the forests (unlikely given it is quite fragile), helps keep the head warm and shed water in its wet habitat, and aids in hearing the low vibrating sounds made by other cassowaries. They possess small vestigial ‘wings’ with 5-6 bare quills and a long claw at the tip of the wing.

Southern cassowaries can grow to a height of two metres, with males weighing up to 55kg and females up to 76kg. Each foot has three claws, better described as nails, with the medial, blade-like nail reaching up to 120mm in length!

Cassowary chicks differ in appearance, with a striped brown and cream pattern. After three to six months, the stripes fade to the brown sub-adult plumage. This is retained until 12 to18 months of age after which the bird begins to take on adult characteristics. Maturity is reached at 3.5 years of age for females and 2.5 years for males.

Signs

Cassowary Dump Photo © Matt Bradford CSIRO

  • Large dung piles
    • Full of seeds but may also contain invertebrates and plants (see Diet)
    • Most visible on rainforest walking tracks and roads
  • Three-toed footprint in soft soil or mud (approximately 180mm for adults)
  • Deep rumbling sound used to indicate presence and response to threats.

Habitat

  • Tropical rainforests of north-east Queensland, Papua New Guinea and Seram and Aru islands
  • Also found in melaleuca swamps, mangrove forests, and sometimes grassland, savanna and palm forest not far from rainforest vegetation.

Ecology

Life History

  • Females and sub-adults are usually solitary, while males are frequently with chicks or young sub-adults); they are generally intolerant of other cassowaries except during mating and when fallen fruit is abundant
  • Females appear socially dominant
  • Life span of approximately 30 years in the wild and between 18 to 50 years in captivity.

Breeding

Male Southern Cassowary and chicks Photo © Margaret Thorsborne

  • Mating season is from early June to September
  • Females may mate with more than one male in the season
  • Females lay three to five olive green eggs, between June and October
  • Male incubates eggs for approximately 50 days
  • Male raises chicks alone
  • After approximately 9-18 months, with the onset of the next breeding season, the juveniles leave the male and begin to fend for themselves.

Diet

  • Primarily fruit, known to feed on the fruits of more than 240 plant species
  • Will consume invertebrates, plants, fungi, carrion as well as small vertebrates when available
  • Cassowaries play an important role in the ecology of rainforests. They are one of only four seed-dispersing animals that can disperse the seeds of large (up to 6cm in diameter) rainforest fruits, and can do this over longer distances than the other dispersers of large seeds
  • Consume an average of 2.9kg of fruit per day in captivity.

Home range

  • Home range fluctuates, depending on availability of food and mating season
  • Home range is estimated to be between 0.52km2 to 5km2 in coastal lowlands, but up to 12km2 in upland regions
  • Home ranges overlap both within and between the sexes though the overlap between males and females is greater
  • Females’ home ranges usually overlap with those of several males
  • They only exclude other birds during the mating season when they can aggressively defend a mating territory.

Distribution

Southern Cassowary Distribution Map © EA/WPSQ

  • Found in north-eastern Australia, Papua New Guinea and the Aru and Seram Islands
  • Cassowaries are found in three broad populations in north-eastern Australia:
  1. Cape York (far northern population): far northern Cape York Peninsula, centred on the much less extensive vine forests of Lockerbie and McHenry Uplands. The Lockerbie Scrub population is possibly extinct with no cassowary having been seen there since the early 1980s
  2. Cape York (northern population): the vine forests of the McIlwraith and Iron Ranges
  3. Wet Tropics (southern population): extends from Big Tableland, south of Cooktown to Paluma, north of Townsville. Distribution of the Wet Tropics population is naturally fragmented but has been reduced due to forest clearing on the Atherton Tableland and coastal lowlands. Currently 89 percent of remaining habitat is in protected areas such as national parks and the Wet Tropics World Heritage Area.

Threats

(In order of how serious the threat is thought to be)

  • Loss, modification and fragmentation of habitat (serious reductions due to land clearing for farming, urban settlement and other development) in the Wet Tropics population on the Atherton Tableland and the coastal lowland and floodplains.
  • Habitat degradation – invasion of weeds
  • Vehicle strikes
  • Dog attacks –juveniles and sub-adults most affected, particularly in areas of residential development or where pig hunting is common even within protected areas.
  • Human interactions – hand feeding cassowaries has many implications:
    1. They may become dependent; when the food source is removed, they may starve
    2. Hand feeding near roads encourages them to return to areas where the likelihood of vehicle strikes is increased
    3. Hand feeding in urban areas makes them more susceptible to vehicle strikes and dog attacks
  • Pigs – may compete with cassowaries for food, eat cassowary eggs and modify habitat, but the significance is not demonstrated.

Conservation

Status

  • Queensland:
    • Wet Tropics (southern population) – Endangered (Nature Conservation Act 1992)
    • Cape York populations (northern) – Vulnerable (Nature Conservation Act 1992)
  • National:
    • Endangered (Environment Protection and Biodiversity Conservation Act 1999)
  • IUCN:
    • Vulnerable (2007 Red List) – Numbers have decreased due to land clearing in the Wet Tropics population
  • Wet Tropics population has reported to have declined from between 2500 to 4000 adults in 1988 but there is no current estimate of the population.

Activities

  • Recovery Plan for the Southern Cassowary 2007
    • Actions to secure long-term protection of cassowary populations
    • Includes improving the protection of habitat and corridors, minimising road kills and dog attacks, establishing a monitoring program in key habitats, and involving the community
  • Approximately 89 percent of habitat in the Wet Tropics population is protected in National Parks and the Wet Tropics World Heritage Area and additional areas are being added
  • Residents in local cassowary regions are creating nurseries of cassowary food plants so rainforest trees can be planted to replace cleared land, and corridors can be planted to join remaining patches of vegetation
  • Road signs and traffic calming devices indicate cassowary habitat and areas where cassowaries may cross roads, especially in the Mission Beach area.

Overall Outlook

  • Cassowary populations in the Wet Tropics have a positive future given the high proportion of their remaining habitat protected to a high level
  • So long as habitat can be maintained, and vehicle strikes, dog attacks and human interactions can be controlled, the Wet Tropics population is likely to have a good long-term outlook
  • The far-northern Cape York population is less secure and more likely to become extinct due to its tiny area of occupancy
  • The northern population currently faces fewer pressures but has a smaller area that it occupies and appears to be at lower density suggesting that any increase in threats will have a more rapid and severe impact.

Bibliography

Bradford, MG, Dennis, AJ, Westcott, DA, (2008).  Diet and dietary preferences of the southern cassowary (Casuarius casuarius) in North Queensland, Australia.  Biotropica, 40: 338-343.

Bradford, MG and Westcott, DA (2010).  The consequences of southern cassowary (Casuarius casuarius, L.) gut passage and deposition pattern on the germination of rainforest seeds.  Austral Ecology. 35:325-333.

Buosi, P. & S. Burnett (2006). The Southern Cassowary (Casuarius casuarius johnsonii): Review of Values and Threats in the Wet Tropics Bioregion, Queensland. A report for DEH. Queensland: Natural Resources Assessments Environmental Consultants.

Crome, F.H.J. & L.A. Moore (1990). Cassowaries in north-eastern Queensland: report of a survey and a review and assessment of their status and conservation and management needs. Australian Wildlife Research. 17:369-385.

Crome, F.H.J. & L.A. Moore (1993). Cassowary populations and their conservation between the Daintree River and Cape Tribulation. II Background, Survey Results and Analysis. Unpublished report to the Douglas Shire Council.

Dennis, A.J. and Westcott, D.A. 2007. Estimating dispersal kernels produced by a diverse community of vertebrates. Pp 201-228. In: Dennis, A.J., Schupp, E.W., Green, P.J. and Westcott, D.A. 2007. Seed dispersal: Theory and its Application in a Changing World. CAB International. United Kingdom.

Garnett, S. Szabo, J. and Dutson, G. 2011. The Action Plan for Australian Birds 2010. CSIRO Publishing, Melbourne.

Green, R.J. 2007.  Refining the conservation management of seed-dispersing frugivores and their fruits: Examples from Australia. Pp 579-598. In: Dennis, A.J., Schupp, E.W., Green, P.J. and Wescott, D.A. 2007. Seed dispersal: Theory and its Application in a Changing World. CAB International. United Kingdom.

Marchant, S. and Higgins, P.J. (eds) 1990. The Handbook of Australian, New Zealand and Antarctic Birds, Parts A and B, Ratites to Ducks. Oxford University Press, Melbourne.

Kutt, A.S., King, S., Garnett, S.T. and Latch, P. 2004. Distribution of cassowary habitat in the Wet Tropics bioregion, Queensland. Technical Report, Environmental Protection Agency, Brisbane.

Latch, P. (2007). Recovery plan for the southern cassowary Casuarius casuarius johnsonii. [Online]. Report to Department of the Environment, Water, Heritage and the Arts, Canberra. Environmental Protection Agency. Available from: http://www.environment.gov.au/biodiversity/threatened/publications/recovery/southern-cassowary/pubs/sth-cassowary.pdf.

Moore LA (2007). Population ecology of the southern cassowary Casuarius casuarius johnsonii, Mission Beach north Queensland. J. Ornithology 148: 357-366.

Westcott D.A. 1999. Counting cassowaries: what does cassowary sign reveal about their abundance? Wildlife Research 26: 61-68.

Westcott, DA, Bentrupperbaumer, J, Bradford, MG and McKeown, A (2005).  Incorporating disperser movement and behaviour patterns into models of seed dispersal. Oecologia 146: 57-67

Westcott, DA, Dennis AJ, Bradford, MG, McKeown, A, Harrington, GN (2008).  Seed dispersal processes in Australia’s Wet Tropics rainforests.  Pp 210-223 in, Stork N and Turton S (eds), Living in a dynamic tropical forest landscape.  Blackwell Publishing, Malden.

Westcott, DA, Setter, M, Bradford MG, Setter, S, McKeown, A (2008). Dispersal of pond apple seeds by the southern cassowary: ecological interactions between a threatened and a threatening species.  Diversity and Distributions 14: 432-439.

Winter, J.W., Bell, F.C., Pahl, L.I. and Atherton R.G. 1987. Rainforest clearing in Northeastern Queensland. Proceedings of the Royal Society of Queensland 98: 41-57.

WEBSITES

http://www.wettropics.gov.au/wwc/wwc_pdfs/CRT/CSummitProceedingsFinal.pdf

(September 2009 Cassowary Summit Proceedings, Cairns)

http://www.birdlife.org/datazone/species/index.html?action=SpcHTMDetails.asp&sid=4&m=0

(Birdlife International)

http://www.iucnredlist.org/details/biblio/22678108/0

(IUCN Red List Accessed September 2016)

http://www.derm.qld.gov.au/wildlife-ecosystems/wildlife/threatened_plants_and_animals/endangered/cassowary.html

(Department of Environment and Natural Resource Management)

http://www.wettropics.gov.au/pa/pa_casso.html

(Wet Tropics Management Authority web site for the Cassowary).

http://www.arf.net.au/operationbigbird/uniquebigbird.html

(Australian Rainforest Foundation species profile).

http://www.cafnec.org.au/campaigns/cassowaries.php

(CAFNEC profile site)

http://www.environment.gov.au/cgi-bin/sprat/public/publicspecies.pl?taxon_id=25986

(Department of Environment and Energy).  Species Profile and Threats Database (SPRAT).

 

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© Wildlife Queensland September 2016

 

Written by Wildlifeqld