Document ID: chunk:federal_register_of_legislation:F2022L00555:body:0:p82
Version: federal_register_of_legislation:F2022L00555
Segment Type: other
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Character Range: 252231–255086

to assist the plasticity of populations to adapt to changing forest tree composition in the future as the local climate changes.
Species distribution models indicate that the range of Koala browse trees will be impacted in the future by climate change (Adams-Hosking et al. 2011a) (section 21.3). Due to the Koala's specialised diet and digestive biology, they have limited physiological ability to cope with drought or heat stress by increasing their leaf intake and subsequent dietary water intake (Lunney and Hutchings 2012). Koalas are thus particularly vulnerable to the increased temperatures and water stress encountered across much of their range due to climate change.

29. Physiology
Koalas are highly susceptible to extreme temperatures, both hot and cold, and drought, particularly where these occur simultaneously and for extended periods of time (Briscoe et al. 2016; Lunney et al. 2014; Seabrook et al. 2014a). The influence of extreme weather events on Koala is mediated by a combination of their physiology, morphology and behaviour.
The acute consequences of extreme heat events on Koalas arise from their physiological and dietary constraints. During periods of heat stress, animals decrease their food intake to reduce the additional burden of heat produced during foraging and digestion processes (Youngentob et al. 2021). This is increasingly hazardous for the Koala which survives on a low energy diet with the majority of their water needs provided by the leaves they eat. If an animal cannot dissipate heat, it can die from extreme heat stress in hot environments (Gordon et al. 1988; Seabrook et al. 2011). In longer drought and extreme heat events, tree death and subsequent starvation and stress on Koalas also reduce, breeding success and survival of young (Davies et al. 2013). Recent work indicates that some Koalas readily use free-standing water when provided, particularly when conditions are hot and dry (Mella et al. 2019, 2020), though this behaviour is thought to be rare (Lunney et al. 2012) and may be indicative of a stressed and/or unwell animal. The use of artificial watering stations may also be associated with the increased spread of disease in Koalas and further research is required.
Koalas have several behavioural responses that can mitigate heat stress. Koalas move daily between food trees and ancillary trees (for example shelter vegetation species and resting trees), and on hot days feed at night when temperatures are cooler (Crowther et al. 2014; Ellis et al. 2010a). Shelter vegetation can be critical for thermoregulation, providing shaded, cooler, climate refugia on heat stress days. The Koala's diet consists of a broad range of tree species but show seasonal and regional preferences for browse species and seek out trees with higher leaf water during drought (Clifton et al. 2007; Davies et