Koala behavioural ecology and implications for their conservation

Background

Koala populations in Queensland are declining significantly (Preece 2007; Seabrook et al. 2011), with the conservation status of the species downgraded to ‘Vulnerable to extinction’ since 2012 (Woinarski & Burbidge 2016). In order to reverse this decline, conservation strategies based on rigorous scientific research on koala ecology, especially population distribution, natural behaviour and potential threats to their survival, are urgently needed. This project aims to improve the effectiveness of koala conservation by exploring aspects of these important topics via three koala research studies.

Study 1: Koala scat surveys

Koala scat surveys are used to identify the presence of koalas in large forested areas (Sullivan et al. 2002; Phillips & Callaghan 2011). However current survey methods are problematic (Cristescu et al. 2012; Woosnam-Merchez et al. 2012) due to their lack of accuracy or efficiency, and hence a new scat search method with improved accuracy and efficiency is required for a better understanding of the distribution of koala populations.

Study 2: Koala bellows

Bellowing by koalas is closely associated with their breeding behaviour (Handasyde et al. 1990; Mitchell 1990), although their precise purpose remains unclear. Previous koala bellow studies on captive koalas have proposed that female koalas may search for large males with whom to mate during their breeding season (Ellis & Bercovitch 2011; Ellis et al. 2011). However, this behaviour has yet to be observed in the wild, and the male body-size-preference by females remains unresolved.

Study 3: Koala-cattle interactions

The decline of koala populations in rural areas of Queensland is primarily due to habitat loss associated with the expansion of land for cattle grazing (Preece 2007). Based on the significant overlap between land used for cattle grazing and koala habitat, conservation strategies have been established to encourage the preservation of koala trees on cattle grazing land. However, anecdotal evidence (Rebgetz 2017) from wildlife carers and wildlife hospital records (RSPCA Queensland 2018), have indicated that cattle injure or even kill koalas when they encounter them on the ground. Studies on actual koala-cattle interactions have never been undertaken.

Aims of the Project

To develop a new koala scat survey method with improved accuracy and efficiency
To investigate koala breeding system with bellow playback experiments
To examine whether grazing cattle are a threat to koalas

Methodology

In the koala scat surveys study, a new method, the Koala Balanced Scat Survey (KBSS), has been developed and quantitatively evaluated by comparing it with the current most widely used method, the Spot Assessment Technique (SAT).
In the koala bellows study, recorded bellows have been broadcast to 25 free-ranging radio-collared Hidden Vale koalas. The behaviour and movement of these koalas have been monitored by cameras to see if they react differently depending on whether the bellow is from a large or small male. All koalas in the study have been provided with both large and small male koala bellow playbacks via speakers, and their behaviour and movement recorded and analysed.
The koala-cattle interaction study is the first to investigate the significance of cattle as a potential threat to koalas. This is being done in three ways: a) through a state-wide livestock-inflicted koala mortality/injury survey, b) by testing the reactions of cattle to a mobile artificial koala model moving near them on the ground, and c) studying changes in the movement and behaviour of radio-collared koalas when they share land with cattle.

Expected outcomes

The application of KBSS is expected to greatly enhance the reliability of koala scat surveys in determining koala distribution, and thus facilitate their conservation in the field.
The results will extend our understanding of koala breeding behaviour associated with bellowing, and consequently also improve the effectiveness of future conservation strategies.
If cattle are a threat to koalas, evidence of cattle-associated koala deaths/injuries will be found via the survey, and the koala model test; and that koalas will show avoidance of cattle when sharing land. Public awareness can thus be raised, and conservation/ farm management strategies developed to minimise the risk to koalas from cattle.

References

Cristescu, RH, Goethals, K, Banks, PB, Carrick, FN & Frère, C 2012, 'Experimental evaluation of koala scat persistence and detectability with implications for pellet-based fauna census', International Journal of Zoology, vol. 2012, p. 12.

Ellis, W & Bercovitch, F 2011, 'Body size and sexual selection in the koala', Behavioral Ecology and Sociobiology, vol. 65, no. 6, pp. 1229-35.

Ellis, W, Bercovitch, F, FitzGibbon, S, Roe, P, Wimmer, J, Melzer, A & Wilson, R 2011, 'Koala bellows and their association with the spatial dynamics of free-ranging koalas', Behavioral Ecology, vol. 22, no. 2, pp. 372-7.

Handasyde, KA, Lee, AK & Sanson, GD 1990, Biology of the koala, Chipping Norton, N.S.W. : Surrey Beatty & Sons.

Mitchell, P 1990, 'Social behaviour and communication of koalas', in AK Lee, KA Handasyde & GD Sanson (eds), Biology of the koala, Chipping Norton, N.S.W. : Surrey Beatty & Sons, pp. 151-70.

Phillips, S & Callaghan, J 2011, 'Spot Assessment Technique: a tool for determining localised levels of habitat use by Koalas Phascolarctos cinereus', Australian Zoologist, vol. 35, no. 3, pp. 774-80.

Preece, HJ 2007, 'Monitoring and modelling threats to koala populations in rapidly urbanising landscapes: Koala coast, south east Queensland, Australia', Ph.D. thesis, The University of Queensland.

Rebgetz, L 2017, Koalas being trampled by livestock amid habitat loss, wildlife experts say, ABC News, <http://www.abc.net.au/news/2017-06-17/livestock-attacks-koalas-more-common-wildlife-experts-say/8625762>.

RSPCA Queensland 2018, Wildlife Outcome Report For Date: 28/09/2015 To 28/09/2018, 28/9/2018.

Seabrook, L, McAlpine, C, Baxter, G, Rhodes, J, Bradley, A & Lunney, D 2011, 'Drought-driven change in wildlife distribution and numbers: a case study of koalas in south west Queensland', Wildlife Research, vol. 38, no. 6, pp. 509-24.

Sullivan, BJ, Baxter, GS & Lisle, AT 2002, 'Low-density koala (Phascolarctos cinereus) populations in the mulgalands of south-west Queensland. I. Faecal pellet sampling protocol', Wildlife Research, vol. 29, no. 5, pp. 455-62.

Woinarski, J & Burbidge, AA 2016, Phascolarctos cinereus, IUCN.

Woosnam-Merchez, O, Cristescu, R, Dique, D, Ellis, B, Beeton, R, Simmonds, J & Carrick, F 2012, 'What faecal pellet surveys can and can't reveal about the ecology of koalas Phascolarctos cinereus', Australian Zoologist, vol. 36, no. 2, pp. 192-200.