Bitterns Boom in Rice Bays

27 Aug 2014 3:08 PM - Article by Michele Sabto for ECOS Magazine, CSIRO Publishing.

The largest population of Australasian Bitterns ever recorded has been found in Riverina rice crops, highlighting the potential role of rice growing – an industry often under fire for high water use – in waterbird conservation.

Ecologist Matt Herring first heard the eerie boom of the Australasian Bittern (Botaurus poiciloptilus) calling out of rice fields in the Riverina (south-western New South Wales) about 15 years ago. He was intrigued.

The Australasian Bittern is a rare and elusive waterbird. Inhabiting shallow freshwater wetlands, it is wary of venturing out onto mudflats or in the open, preferring to lurk within, or on the edges of, wetland vegetation. Its reaction to intruders is to freeze and assume an erect posture – neck outstretched, bill pointing skyward. Sometimes it even sways with the breeze to enhance concealment.

But what the Bittern is most famous for is its characteristic basso call, which may explain the myth of the Bunyip – a fantastical creature said to live in creeks, swamps, billabongs, riverbeds and waterholes.

When Matt first heard that weird call, he thought ‘it was the odd Bittern here and there in the rice crops’.

But it turned out that rice farmers across the Riverina had also been hearing the Bittern’s call. In 2011, a curious grower took a photo and sent it off to BirdLife Australia for identification.

This sparked much interest – BirdLife Australia was at the time was campaigning to have the bird federally listed as endangered in Australia. It is now listed as such and is also listed as globally endangered on the IUCN Red List.

BirdLife Australia joined forces with the Rice Growers’ Association of Australia to begin surveys, led by Matt, of Riverina rice fields for Australasian Bitterns during the 2012-13 growing season (September-October to January).

The study, covering 93 rice paddock study sites – 64 in the Murrumbidgee and 29 in the Murray – reached a preliminary estimate of 500–1000 Australasian Bitterns using Riverina rice crops during the growing season. Matt says it is the largest population of Bitterns ever recorded in Australia.

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