Document ID: chunk:federal_register_of_legislation:F2024L01094:body:0:p19
Version: federal_register_of_legislation:F2024L01094
Segment Type: other
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Character Range: 56862–59832

Declining white gum health
Forty-spotted pardalotes are totally reliant on white gum; as such, any factor that impacts the trees also impacts the bird in the same way. White gums are known to be highly susceptible to stress due to climatic factors, and climate change projections indicate an increasing frequency and intensity of heat waves. 'Ginger tree syndrome' is the term often given to a condition affecting eucalypts following extreme heat events. Elevated ambient air temperatures can cause water stress and hence shrinkage of the bark and trunk, leading to the production of kino; a sap seeps through the bark, turning the trees 'ginger' and providing a visual means of identifying affected trees (Mitchell 2015). Tree mortality typically follows within 12 months.

Potts et al. (2016) found that white gum and Eucalyptus dalrympleana (mountain gum) are both moderately more susceptible to the fungal disease myrtle rust (Austropuccinia psidii) in comparison to other Tasmanian eucalypts—of 122 seedlings tested under laboratory conditions, 34% of white gum and 22% of mountain gum were susceptible (Potts et al. 2016).

3.2.5 Parasitism
The ectoparasitic fly P. longicornis parasitises forty-spotted pardalote nestlings, causing severe rates of mortality (Edworthy et al. 2019; Alves et al. 2020). The fly lays its eggs in the nests of forty-spotted pardalotes and once the nestlings hatch, the larvae burrow under their skin and feed on their blood. This leads to very high mortality rates of fly-struck pardalote nestlings and is now the primary cause of nesting failure. In areas of high ectoparasitic fly prevalence on Bruny Island, up to 81% of all nestlings are killed, making it the primary cause of nesting failure (Edworthy et al. 2019; Alves et al. 2020).

The fly has been detected in other populations but prevalence across the forty-spotted pardalote range is unknown. The threat of parasitism may interact with increasing temperatures caused by anthropogenic climate change. The overall potential threat this poses is high given that fly development is temperature dependent (Edworthy 2016b), and so prevalence may increase as a result of increasing temperatures caused by climate change. The population decline of the forty-spotted pardalote further increases its vulnerability to parasitism-induced mortality (Edworthy et al. 2019).

Research by Alves et al. (2020) found that forty-spotted pardalotes could effectively "self-fumigate" their own nests when provided with sterilised chicken feathers treated with bird-safe insecticide. In self-fumigated nests, 95% of hatchlings survived to fledging compared to just 8% of hatchlings in untreated control nests (Alves et al. 2020). At present, this novel technique is a highly effective and inexpensive method of reducing parasitism of chicks. However, further research is required to manage this threat in the longer term.

3.2.6 Small population size
Small, isolated populations may lose their