The Use of Aerial Surveys for the Detection of the Brolga Grus rubicunda Through South-West Victoria: Key Considerations for the Wind Industry

Abstract

The brolga Grus rubicunda breeds primarily in shallow freshwater wetlands and is classified as Vulnerable in Victoria. Specific guidelines have been developed to mitigate potential impacts of the wind industry on brolga populations. Identifying brolga nest sites is a key aspect of these guidelines and aerial surveys are suggested as one method. We used aerial surveys to identify brolga nesting sites over a large area of south-western Victoria during the 2009 and 2010 breeding seasons. We surveyed approximately 800 km² over the two seasons, and detected 44 nests which were subsequently ground-truthed. Of these nests, nine were confirmed as belonging to brolgas, 14 as belonging to black swan Cygnus atratus and 21 were either abandoned or not accessible. Aerial surveys covered a much larger survey area over a shorter time period compared with ground surveys (approximately half the time), and covered wetlands not otherwise easily accessible (e.g. sites located away from roads and/or on private property). Given the difficulties in distinguishing between brolga and black swan nests, it is imperative that wetlands are ground truthed to accurately identify nests. Given that not all nests are active concurrently in a given season, our results reveal that at least two aerial surveys are required across a study area to detect 75 % of the brolga nests in a season.