Stage 2- EcoAerial was engaged by Melbourne Water to undertake microbat surveys at four Melbourne Water reservoir reserves; Sugarloaf, Running Creek, Yan Yean, Toorourrong and, land owned by Melbourne Water outside of the reservoir network. The methods entailed deploying harp traps and passive / active bat detector surveys. The surveys follow on from surveys undertaken in 2019 / 2020 at Silvan, Cardinia, and Sugarloaf Reservoirs.

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The key objective of the surveys was to focus on two state significant species; the Flora and Fauna Guarantee Act 1988 (FFG Act) listed Eastern Bent-winged Bat Miniopterus orianae oceanensis (Critically Endangered) and Large-footed Myotis Myotis macropus. The Large-footed Myotis was previously listed as Near Threatened in the now obsolete Advisory List of Threatened Fauna.

A total of one-hundred and eleven microbats were captured across the surveyed areas comprising nine species. The target species, Eastern Bent-winged Bat and Myotis were caught at an overflow tunnel at Toorourrong Reservoir. Myotis were caught at Running Creek and Yan Yean Reservoirs. Up to a half a dozen Myotis were also observed foraging over the water at Running Creek Reservoir.

The Toorourrong records are the first at the reservoir since 2012. The Running Creek Reservoir had not been surveyed since 2000; three Myotis were caught. Yan Yean continues to support a healthy population of Myotis with 10 bats caught in a 4-hour period and several Myotis seen foraging over the water. Neither Eastern Bent-winged Bat or Myotis were caught or observed at Sugarloaf Reservoir notwithstanding the ecological similarities to reservoirs where the target species were caught.

Although not part of the project, bat friendly gates installed on three decommissioned aqueduct tunnels at Sugarloaf Reservoir in 2020 were surveyed to assess if they are used for roosting or foraging. There was no evidence that they are being used, although a large bat was seen investigating the entrance of one of the gates.

Melbourne Water Reservoir Bat Surveys