Australasian Bittern Project
Cameron Brown, Save Tootgarook Swamp, Inc., Victoria, Australia
The Tootgarook Swamp is the largest remaining shallow freshwater marsh in the Western Port and Port Phillip Bay region and contains the largest intact stands of tall marsh and sedge wetlands on the Mornington Peninsula. The loss and alteration of these habitats in the region has resulted in a reduction in the occurrence of several freshwater wetland obligates including the Australasian Bittern, Botaurus poiciloptilus.
The Australasian Bittern has been regularly documented within the Tootgarook Swamp since 1891. Recent observations, including breeding calls in spring, lead to the belief that breeding could potentially be occurring in the 650-hectare wetland. The Australian Bittern is listed federally as Endangered under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act) and identifying and securing habitat for the species is a priority to its conservation.
Objectives, outcomes and conclusions
Given its cryptic appearance and behavior of the species and the logistical difficulties in conducting biodiversity surveys in preferred wintering habitat (often dense tall vegetation) the project sought to compliment traditional survey methods with remote sensing technology including song meters and wildlife cameras.
From 07/2016 to 12/2016 the monitoring project complimented on-ground physical surveys with deployment of:
- a SM3 Song Meter (donated by Birdlife Australia) within the lowest part of the Tootgarook Swamp wetland
- seven wildlife cameras at locations nearby to where Australasian Bitterns had been flushed in previous years
- An unmanned aerial vehicle (UAV) with mounted camera in other nearby areas
Australasian Bittern was recorded in a combination of all survey techniques. The new combined survey methods also detected 20 additional species (17 birds, 2 frogs and a bat) to the manual observation survey, with 12 of these species purely recorded by the SM3+ Song Meter. Wildlife cameras and UAV have also been able to record unique behaviours that previously have not been seen before in the swamp, with the animal acting more natural in their environment.
Information gathered from the Song Meter and the Wildlife cameras data indicates that several species of birds were recorded on the cameras that were not picked up by the Song Meter, as well as birds that were not picked up by Song Meter and wildlife cameras that was through manual observation and vise-versa. Overall it is the authors view that the overall strategic approach to combined observation techniques gave an overarching interpretation of the avian species composition in the area.
These findings confirm the application of remote sensing technology is an effective method for detecting fauna in wetland environments.
Passive surveillance is an important facet of capturing images or sounds of wildlife with minimal disturbance by humans as wildlife can sense and/or have an acute awareness of human behaviour. Active surveys can deal completely different results as most wildlife try to avoid humans if possible.
This is something you can witness even just sitting quietly in a car [example 1] at a nature reserve or park, when wildlife may be around but the minute you exit the vehicle the wildlife becomes aware you may be a threat.
This really shows the importance of using different methods and equipment when conducting fauna surveys to detect species. Desktop surveys of fauna species should only be used as a guide to potential expected species encounters in the field, thus allowing time for the appropriate preparatory measures to be undertaken prior to survey start. Recorded data from the song meters has been sent to Birdlife Australia for analysis. The recorded field data was also analysed by the author.