Roadsand Maritime Services (RMS) proposes to construct a four lane road and overrail bridge on the Olympic Highway at Kapooka. The proposal would also include realigning about 2.7 kilometres of the Olympic Highway and upgrading the Olympic Highway/Camp Access Road intersection. The proposal also includes permanent and temporary features for traffic management, pedestrian access, stormwater management, wildlife movement, noise attenuation, landscaping and weather monitoring. It is expected that the project will take about 18 months to construct.
The proposal would require the removal of 32.5 hectares of vegetation, 12.8 hectares of this vegetation is BoxGum Woodland listed under the Threatened Species Conservation Act 1995 (TSC Act) and/or Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act). The removal of BoxGum Woodland will entail the loss of 788 trees, 30 that have a dbh (diameter at breast height) greater than 40 centimetres. Included in the 788 trees to be removed, 13 trees have hollows that are likely to support tree roosting microbats.
WSP was commissioned by RMS to undertake preconstruction surveys targeting microchiropteran bats. The surveys were required by the Director General (Office of Environment and Heritage (OEH)) for a Species Impact Statement for a number of threatened microchiropteran species. The species targeted were Corben’s Longeared Bat, Eastern Bentwing Bat, Southern Myotis and Yellowbellied Sheathtail Bat.
The survey effort was aligned to both NSW and Commonwealth bat survey guidelines. Five sites within/or adjacent to the subject site were selected based on habitat deemed suitable for surveying microbats. A further seven sites were selected within the locality that are outside of the subject site. The surveys focused on areas of remnant vegetation, large trees, culverts and dams. A total of 13sites (26trap nights) were surveyed using traps, 12sites (17detector nights) using bat detectors, vehicle based detector surveys totalling 31kilometres and 260 minutes of roost searches.
Harp traps captured 111 individuals (including two recaptures) of eight species with 28 females having bred in the preceding breeding season. Two of the four targeted threatened species were recorded in the study area. Southern Myotis was captured at a dam, Yellowbellied Sheathtail Bat was recoded at a dam and a third species not included in the DGRs was potentially recorded using bat detectors, the Little Pied Bat. It is considered highly unlikely that the Eastern Bentwing Bat and Corben’s Longeared bat are present within the study area.
The trapping results showed that large old trees with overhanging branches were a focal point for bat utilisation, 49% of captures occurred at traps set up under large old trees. Traps placed next to dams caught 29% and culverts 11%, the balance of captures were in cluttered understorey vegetation.
Bat detectors recorded 5637 bat files of which 389 were identified to a species level. The number of captures, bat call activity and presence of breeding females within the study area indicates that the habitat supports populations of a range of bat species.
Southern Myotis is potentially at greater risk of being impacted by the proposal due to its reliance on roosts being located close to its foraging areas over water. However, the habitat at the site of capture is not what would be considered important habitat and only one tree is scheduled for removal near the capture site. Although further targeted surveys for Southern Myotis would be beneficial to understand if they are opportunistically foraging over the dam, the dam will be retained and as a consequence the realignment will not impact on foraging.
The installation of a range of nest boxes has been identified as an important compensatory strategy (GHD 2012). The type and thickness of construction material can influence occupation. Nest boxes constructed of 15 millimetre UV resistant recycled plastic can be expected to have a 40~ 50year life span and have excellent thermal qualities. WSP recommends that all next boxes intended for all species are constructed of UV resistant recycled plastic.
While the removal of vegetation is likely to have some impact on the availability of foraging and roosting habitat for threatened bats present in the study area. This impact is not likely to be significant as there is alternative habitat within commuting distance to the study area. To compensate for the loss of hollow bearing trees, WSP recommends that alternative roosts in the form of bat roost boxes are installed in the study area in accordance with RMS Biodiversity Guidelines (2010).