Shy Heathwren (Kangaroo Island)  |  

Calamanthus cautus halmaturinus (Hylacola cauta halmaturina)

Status: Vulnerable on the EPBC Act list

Adult males are brown on the upper body, and pale below with bold dusky streaking, with a prominent white supercilium. They have rich rufous upper tail-coverts, blackish tails with prominent white tips, and white patches at base of primary feathers, forming a strongly contrasting white spot on folded wings. Adult female underparts are more buff and less heavily streaked than the males. Kangaroo Island Shy Heathwren weigh around 15 g and have a length of around 14 cm. They have a short straight stout bill, long legs, and a long tail held strongly cocked like a fairy-wren (Malurus spp.). They differ slightly in size, upper body colour and density of streaks. Morphologically they are very similar to the Chestnut-rumped Heathwren (Calamanthus pyrrhopygius), although Chestnut-rumped Heathwrens occupy different habitats and are not found on Kangaroo Island, therefore Kangaroo Island Shy Heathwrens are unlikely to be misidentified.

Government evidence of impact of climate change:

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  • Australian Government, Conservation Advice, Calamanthus cautus halmaturinus (Hylacola cauta halmaturina)

    Climate change Increased likelihood of Status historical; current future Average temperatures in Australia have extreme events (i.e.; Confidence known increased by around 1.4 C in the past heatwave and drought) century (BOM CSIRO 2020 IPCC Consequence severe 2021); and global temperatures are likely Trend increasing to exceed 1.5 C in the next 20 years if Extent across the entire range global greenhouse gas emissions are not reduced immediately (IPCC 2021).
    The cumulative effect of the climate anomalies has led to; and will continue to; increase the likelihood of extreme events such as droughts and heatwaves (BOM CSIRO 2020).
    This change in climate may have detrimental impact on Kangaroo Island Shy Heathwren and their habitat.
    Climate anomalies will also increase the risk of wildfire (see Increase in frequent; large extent; high intensity wildfires).
    Analysis by the Wildlife and Threatened Species Bushfire Recovery Expert Panel; based on intersecting the modelled distribution of the Kangaroo Island Shy Heathwren and the National Indicative Aggregated Fire Extent Dataset; indicated that 67 of the range of the subspecies was within the extent of the 2019 2020 bushfires (Legge et al. 2020).
    An analysis done by the National Environment Science Program (NESP) Threatened Species Recovery hub showed that a large proportion of the range of the Kangaroo Island Shy Heathwren was affected by the 2019 2020 bushfires 51 was burnt in high to very high severity fire; and a further 11 was burnt in low to moderate fire (Legge et al. 2021).
    Threats The most prominent threat that has caused the subspecies to decline is frequent; large extent; high severity wildfire particularly the 2019 2020 bushfires; where half of the Kangaroo Island was impacted (Paton et al. 2021).
    While fire is integral to the ecology of Kangaroo Island; the 2019 2020 bushfires were the most extreme in recorded history and were unprecedented in their scale; speed and intensity (Government of South Australia 2020b).
    The flammable nature of some weeds; including non endemic species such as Tasmanian Blue Gum (Eucalyptus globulus); may also increase fire risk and severity (Government of South Australia 2021).
    Table 1 Threats impacting Kangaroo Island Shy Heathwren Threat Status and severity a Evidence Fire Increase in frequent; large Status historical; current future While fire is vital to the ecology of extent; high intensity Confidence known Kangaroo Island; the 2019 wildfires bushfires were the most extreme in Consequence severe recorded history; burning approximately Trend increasing half of the island (DEW 2020 Todd Extent across the entire range Maurer 2020).
    Proposed changes include increased fire prevention works such as prescribed burns; mechanical vegetation removal and increased asset protection zones and buffer zones (BirdLife Australia 2021; pers comm July).
    For example Ensure fire suppression strategies also consider impacts on the population or its habitat.
    The number of locations was determined using the 2019 2020 fire extent on Kangaroo Island; which heavily impacted the western side of Kangaroo Island; though unburnt habitat fragments remained within the fire affected area.
    The risk of a fire extirpating all individuals on the eastern side of the island was considered.
    Given there are lower fuel loads and less contiguous vegetation cover in east; as well as greater access to fire fighting resources; the risk of fire impacting this entire area is reduced.
    An analysis by a team from the NESP Threatened Species Recovery Hub shows that a large proportion of the range of Kangaroo Island Shy Heathwren was affected by these fires 51 was burnt in high to very high severity fire; and a further 11 was burnt in low to moderate severity fire (Legge et al. 2021).