Archived 2017 topics: Southern Cassowary (Casuarius casuarius): downlist to Least Concern?

Southern Cassowary, Casuarius casuarius, has a wide distribution, occurring in New Guinea (both in Indonesia and Papua New Guinea) and north-eastern Australia. It inhabits predominantly rainforest, but may also occasionally be seen in adjacent habitats such as fruit plantations, savannah forest and mangroves. Garnett et al. (2011) estimated that the population in Australia may number c.2,500 mature individuals, and Westcott et al. (2014) estimate it at 4,000 individuals, which would equate to c.2,670 mature individuals, from population densities of 0.04-1.8 birds per km² in rainforest. Densities are likely higher in its New Guinean range, given densities of up to 21 individuals per km2 have been recorded for its congener the Northern Cassoway, C. unappendiculatus (Pangau-Adam et al. 2015). Additionally its New Guinean range is c.15 times the size of its range in Australia (G. Dutson in litt. 2016), and so the global population size may be tentatively placed in the range of 20,000-49,999 mature individuals (G. Dutson in litt. 2016).

Historically, the species has been threatened by habitat loss and fragmentation as well as hunting. Habitat loss in Australia caused the species to undergo a rapid population decline there, which in part has contributed to its current listing as Vulnerable under criterion A2cde (see BirdLife International 2017). However, its habitat received protection by World Heritage listing in 1988, and numbers have remained relatively stable since then (Garnett et al. 2011, Westcott et al. 2014). Habitat loss is occurring within the New Guinean part of its range, but this is likely to be causing only a very slow decline because in the species’ core range of Gulf and Western Provinces, Papua New Guinea, 4% of rainforest was logged and 1.4% of rainforest was deforested between 2002-2014 (Bryan and Shearman 2015).

The other major impact on this species is hunting. On New Guinea the species be under pressure from hunting as it is of cultural importance and a source of food for subsistence communities (Coates 1985, Beehler et al. 1986, K. D. Bishop in litt. 1999). Such activities may be unsustainable and the species is reported to have disappeared from some sites as the species is traded to supply markets in more densely populated areas (Johnson et al. 2004). There has been a recent increase in the hunting of this species for use in traditional bride price gifts, but this probably only affects a small number of individuals and so may not be having a significant effect on the population (I. Woxvold pers. comm. per G. Dutson in litt. 2016). Cyclones can also have an impact on this species, as displaced individuals make be more likely to be hit by cars (Dwyer et al. 2016), and there is increased susceptibility to disease such as tuberculosis after such events (Cooper 2008).

The 3 generation period for this species is 37.5 years, and so trends over this period would include part of the severe decline in Australia. However, the Australian population is only a fraction of the global population, and only part of the severe decline falls into this period, with the population relatively stable there since 1988. The impact of forest loss and hunting in New Guinea is also unlikely to have caused rapid declines over this period, and the global rate of decline has been suspected to be <10% over the past 3 generations (G. Dutson in litt. 2016). Thus the species is unlikely to approach the threshold for Vulnerable under any criterion and would warrant listing as Least Concern. However, we do welcome any further information and comments, particularly regarding the potential rate of decline over the past 37.5 years as if the species may be considered to have declined by >20% within this time period it may warrant listing as Near Threatened under criterion A2cde.

 

References

Beehler, B. M.; Pratt, T. K.; Zimmerman, D. A. 1986. Birds of New Guinea. Princeton University Press, Princeton.

BirdLife International. 2017. Species factsheet: Casuarius casuarius. Downloaded from http://www.birdlife.org on 29/03/2017.

Bryan, J. E.; Shearman, P. L. (Eds). 2015. The State of the Forests of Papua New Guinea 2014: Measuring change over the period 2002-2014. University of Papua New Guinea, Port Moresby.

Coates, B. J. 1985. The birds of Papua New Guinea, 1: non-passerines. Dove, Alderley, Australia.

Cooper, D. 2008. Cassowaries still feeling cyclone pain. Available at: http://www.abc.net.au/science/articles/2008/02/21/2166195.htm. (Accessed: 14 December).

Dwyer, R. G.; Carpenter-Bundhoo, L.; Frankline, C.; Campbell, H. A. 2016. Using citizen-collected wildlife sightings to predict traffic strike hot spots for threatened species: a case study on the southern cassowary. Journal of Applied Ecology 53(4): 973-982.

Garnett, S. T.; Szabo, J. K.; Dutson, G. 2011. The Action Plan for Australian Birds 2010. CSIRO Publishing, Collingwood.

Johnson, A.; Bino, R.; Igag, P. 2004. A preliminary evaluation of the sustainability of cassowary (Aves: Casuariidae) capture and trade in Papua New Guinea. Animal Conservation 7(2): 129-137.

Pangau-Adam, M., Mühlenberg, M., Waltert, M. 2015. Rainforest disturbance affects population density of the northern cassowary Casuarius unappendiculatus in Papua, Indonesia. Oryx 49(4): 735-742.

Westcott, D. A.; Metcalfe, S.; Jones, D.; Bradford, M.; McKeown, A.; Ford, A. 2014. Estimation of the population size and distribution of the southern cassowary, Casuarius casuarius, in the Wet Tropics Region of Australia. Report to the National Environmental Research Program. Reef and Rainforest Research Centre Limited, Cairns.

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3 Responses to Archived 2017 topics: Southern Cassowary (Casuarius casuarius): downlist to Least Concern?

  1. Phil Gregory says:

    Seems to be stable in the Cairns hinterland, but roadkill is a constant threat wherever roads intersect the habitat, we have had 2 killed in the last two years that way. In New Guinea hunting is definitely significant and causes local declines to near extinction, but I doubt a massive 20% decline over the total range. Just be aware that changing status for it in Australia may cause problems, if it gets downgraded then it is no longer a flagship species for conservation and our far too often indifferent local governments will have even less reason to protect habitat…..A sad reality of life here these days but there we are.

  2. Stephen Garnett says:

    There is a good argument for Least Concern. The earlier assessment gave too much weight to the Australian declines. However, while the population in Australia appears to be stable, it is unlikely to be removed from local legislative lists because to do so there needs to be a demonstrable increase in the population or the relevant committee must be convinced that removal of the species from their list will do no harm to the population. Neither is likely to be true for the Australian population, even if it no longer meets Vulnerable or Near Threatened under the IUCN Red List criteria.

  3. Hannah Wheatley (BirdLife) says:

    Preliminary proposals

    Based on available information, our preliminary proposal for the 2017 Red List would be to adopt the proposed classifications outlined in the initial forum discussion.

    There is now a period for further comments until the final deadline of 4 August, after which the recommended categorisations will be put forward to IUCN.

    Please note that we will then only post final recommended categorisations on forum discussions where these differ from those in the initial proposal.

    The final 2017 Red List categories will be published on the BirdLife and IUCN websites in early December, following further checking of information relevant to the assessments by both BirdLife and IUCN.

Comments are closed.