Population assessment of the Endangered Forty-spotted Pardalote Pardalotus quadragintus on Maria Island, Tasmania

The Forty-spotted Pardalote Pardalotus quadragintus is one of the smallest birds in Australia and is endemic to Tasmania, where it occurs only in forest or woodland containing White Gum Eucalyptus viminalis. It is listed as Endangered under the Tasmanian Threatened Species Protection Act 1995 and Commonwealth Environment Protection and Biodiversity Conservation Act 1999. A habitat-stratified survey of Forty-spotted Pardalotes on Maria Island, off the eastern coast of Tasmania, was undertaken in August 2023 to provide a robust estimate of the population. Initial stratification using available vegetation mapping overestimated the availability of suitable habitat based on survey-site habitat evaluations. Forty-spotted Pardalotes were detected at 14 of 74 survey sites, with all detections being at sites where White Gum was the main tree species present. Their mean density was 1.66 birds per hectare, with an estimated total population of 847 birds (CV 0.38, confidence intervals 404–1776 birds). This estimate is consistent with previous uncorrected count-based estimates, although comparisons with historical counts are highly subjective given the substantial methodological differences. Only ~5% of Maria Island supports the preferred habitat for this species and further research on the requirements for, and abundance of, suitable microhabitat is recommended to further refine population estimates and guide conservation management actions.