Spring Calls for Bitterns

Spring has arrived and it’s time for all good birders to get busy! There are many options for birders in spring as the bush birds are in breeding mode and the migratory waders are returning from the north. But for a dedicated crew, the calls of bitterns beckon and cannot be ignored!


Australasian Bittern in flight at Kulinilup Swamp, part of the Muir-Unicup wetlands near Manjimup.

We head out to swamps and lakes at twilight throughout the south-west of Western Australia and listen for the resonant booming of the endangered Australasian Bittern and the staccato “wooks” of the Australian Little Bittern. The male Australasian Bittern usually calls from September to December in WA but can call from as early as August and to as late as January.


The Australian Little Bittern is best heard in south west WA from October to December. If you don’t know the calls, they are available at http://www.birdsaustralia.com.au/our-projects/bittern-survey.html, along with further information on these two swamp dwelling bitterns.

Both bittern species are rarely seen as they are cryptic birds that hang out in rushes and sedges and so surveys concentrate on listening at wetlands during the breeding season. Australian Little Bittern are particularly difficult to see as their small size makes them harder to spot. They also typically remain in tall, dense reed beds, whereas the larger Australasian regularly moves into shorter sedgelands to feed.

Australian Little Bittern at Lake Monger.

Australasian Bittern are found from Yanchep to Cape Arid but are more common in the Manjimup and south coastal areas. However in any part of their WA range they are either “uncommon” or “rare”. Australian Little Bittern are found in the same area, but are also present in the Kimberley. Again these little critters are uncommon to rare throughout their range but could be in a swamp near you!

The best way to see or hear these birds is to become a volunteer for the joint Birds Australia WA (BAWA) and Department of Environment and Conservation (DEC) Australasian Bittern project. Evening listening surveys are conducted at metropolitan wetlands, along with occasional daylight flushing and nest-search surveys. Multi-day expeditions, involving both daylight flushing and evening listening surveys, are also organised for wetlands on the south coast and near Manjimup. The following surveys are currently planned (more may be organised later in the season):
• Esperance/Cape Le Grand area – October 9-15
• Muir-Unicup wetlands – October 28-30
• Albany/Manypeaks area – November 4-6
For more information on the project, or to volunteer for any of these surveys, contact Robyn at r.pickering@birdsaustralia.com.au.

In 2010/11 the BAWA and DEC surveys found a record 18-24 Australasian Bittern in 12 wetlands (mostly on the south coast due to drought in other areas) and 17 to 19 Australian little Bittern were recorded in 15 wetlands (Pickering 2011). This compares to 16-21 Australasian Bittern at over 10 wetlands and 20-27 Australian Little Bittern from 12 wetlands in 2009/10 (Pickering 2010).

Australasian Bittern feeding habitat at Lake Pleasantview east of Albany.

References
Pickering, R. (2011). Summary of the Australasian Bittern Project 2010/11. Western Australian Bird Notes Vol. 138 June 2011 p. 15-17.
Pickering, R. (2010). Summary of the Australasian Bittern and Australian Little Bittern Surveys 2009/10. Western Australian Bird Notes Vol. 134 June 2010 p. 13-14.
All past issues are available at http://www.birdsaustralia.com.au/the-organisation/wa-bird-notes.html