An urban cryptic – the Bush Stone-curlew

Bush Stone-curlews (Burhinus grallarius), or Bush Thick-knees, are a relatively large but slim, mainly ground dwelling, nocturnal bird. Although it looks a bit like a wader it is related to the oystercatchers, avocets and plovers and is a terrestrial predator filling an ecological niche similar to that of the road runner in North America (Wikipedia 2016). There is only one other bird in the Burhinidae family in Australia, the Beach Stone-curlew (Esacus magnirostris).

Bush Stone-curlews are found in part of the Kimberley and its off-shore islands, the Pilbara, Gascoyne and south-west of WA, and seldom in the sandy deserts and east of Southern Cross (Johnstone and Storr 1998). This bird is found is a variety of habitat across Australia from the open forest, eucalyptus woodlands, grassy plains and arid shrublands and around inland rivers and streams. It is relatively common in the northern areas but has become very rare in the south and south west, predominantly in response to feral predators but possibly also due to habitat fragmentation.

During the day, Bush Stone-curlews tend to remain inactive, sheltering amongst tall grass, thickets and low shrubs and relies on its cryptic plumage for protection from predators. If spotted, they will remain motionless and visual predators like raptors and humans will struggle to find them, however, animals that hunt by scent like foxes, cats and goannas will still be an issue. Although they prefer to stand motionless as a defence strategy, they are very agile and quick on the ground and will still fly if required.

The Bush Stone-curlew has a distinctive , wailing call, which has variously been described as melancholy, mournful, frightening and eeire. It has also been described as akin to the call of a screaming woman or baby and can be quite unsettling if a mob of the birds are calling at night. In most Australian aboriginal cultures these birds have a close association with death.

It normally lays a clutch of two eggs in a slight depression in the ground, and they area a dull, greyish, off-white to light brown colour with grey brown or olive spots. Eggs are very difficult to find.

The Bush Stone-curlew is not listed under the EPBC Act 1999 and were recently removed from threatened species lists maintained by the Department of Parks and Wildlife.

We have observed Bush Stone-curlews throughout the Pilbara and were fortunate to observe three breeding pairs near Redmont Camp (170km NE of Newman, WA) a few years back. In all cases, both adults were present with one sitting on the eggs and the other watching guard. Both remained motionless when we drove or walked past but we didn’t get too close so prevent disturbing the birds.

Last week Graham observed a Bush Stone-curlew in the metropolitan suburbs in Perth. This is not a common occurrence and after some searching on social media we discovered that this bird is one of the captive bred birds released by the Perth Zoo into Whiteman Park. The Perth Zoo has bred and released Bush Stone-Curlews into the Wadderin Sancutary in the State’s central Wheatbelt in 2012 and into Whiteman Park in 2013, 2014 and 2015. The bird observed by Graham had a reflective leg band indicating that it was one of the 2013 birds released into Whiteman Park. Some of these birds still live in Whiteman Park, but others have moved around Perth and have been observed at Herdsman Lake, Challenge Stadium, John XXIII College, Bullcreek Shopping Centre, Rous Head and other locations around Perth.

The release of these birds into wildlife sanctuaries assists with the re-establishment of populations in areas where they have previously been impacted by habitat fragmentation, and feral cats and foxes.

This is an excellent example of how captive management and breeding programs can contribute to the vertebrate fauna assemblages of threatened species and is perhaps something that we should do more of.

References

Johnstone, R. E., and G. M. Storr. 1998. Handbook of Western Australian Birds. Volume 1 – Non-Passerines (Emu to Dollarbird). Western Australian Museum, Perth.

Photo credit: Top – Bush Stone-curlew in a captive breeding enclosure sitting on eggs; middle – Bush Stone-curlew sitting on eggs in the Pilbara; bottom – a Bush Stone-curlew standing near a female which is incubating eggs.