Brolga FAQ 2

This page covers Brolga food, drinking, nesting and development. Size, locations and population numbers are in FAQ 1, and an introduction to Brolgas and Sarus Cranes with comparison photos and calls is in Ozcranes Australia/ New Guinea Cranes Intro.


Food and water

Brolgas are omnivorous, eating many foods: wetland plant tubers, grains (including crops), insects, spiders, molluscs, frogs, mice, snakes. They wait and watch to catch fish or water invertebrates, or probe into silt or mud for tubers and food like mussels, see images below. But they can also actively swoop and capture prey: a Brolga pair in captivity caught and ate mice in their pen [1]. Brolgas drink and bathe every morning and evening, and during the day in hot weather. Cranes drink by scooping water up into the bill then throwing the head back to swallow, probably using both gravity and some tongue movement. An image of a Brolga ‘scooping up’ water is in the sidebar.

[1] CB Brown & GW Archibald (1977). ‘Captive Brolgas and Sarus Cranes prey on wild mice.’ Emu 77: 39-40.

Brolga fishing Brolga hunting mussel Brolga eating mussel

↑ L: Brolga poised completely still, waiting for prey (P Merritt). C & R: Brolga with head underwater, hunting and eating mussels, note the long tongue (Rob Gray)

↓ L: Brolga hunting in mud, Mary River, NT (Lip Kee, used under a Creative Commons Attribution-ShareAlike 2.0 Generic Licence. R: Brolga probing for bulbs, SE Australia (P Merritt).

Brolga hunting in mud Brolga probing for bulbs

LINKS: Tony Ashton Blog: Brolga catching a dragonfly and Brolga taking rat killed by cane harvester

VIDEOS: Short (partial) sequence of adult Brolga drinking, in the NCCMA Brolga nest video, go to 2min 37secs; Brolgas feeding at Fogg Dam, Northern Territory (YouTube); Brolgas wading in water, and in mud (from Brolga Recovery Group, on Vimeo).

Salt water

Brolgas use fresh and saline wetlands, and are the only crane to have glands near the eye (or specialised tear ducts) that excrete excess salt. The reference [2] states that Brolgas ‘roost frequently on saline areas at night, and drink fresh and salt water’ (page 515). However the paper deals with the biological processes involved and gives no detail on Brolgas drinking in the wild, or the level of salinity in the waters they drink. Presumably the statement derives from Blackman's vast experience in ecological studies of northern Brolgas. Ozcranes is pleased to present images and a firsthand observer report on Brolgas drinking sea water.

[2] MR Hughes & JG Blackman (1973). ‘Cation content of salt gland secretion and tears in the brolga, Grus rubicundus (Perry) (Aves: Gruidae)’ Aust J Zool 21(4): 515-518.

Brolgas drinking seawater Brolga footprints

← Brolga family drinking seawater, and their footprints on the beach (Bob Forsyth)

In April 2008 Bob Forsyth saw three Brolgas – a pair with one young of the season – walk down to the shore on Sweers Island, Gulf of Carpentaria. Each bird took a maximum of two very short drinks of sea water, then they left: so the ‘trip’ was specifically to drink. There was no fresh surface water on Sweers Island at the time (drinking water comes from wells). Bob said he forgot to taste the sea water at that spot himself, but he believes with the normal tides it would be saline. Observers report up to 20-30 Brolgas on the island, they often feed on sandbanks (a photo of 15 Brolgas on the beach is in Brolga FAQ 3»). Lyn Battle of Sweers Island resort adds: “We have seen them dig holes at high tide, and the Bentinck ladies have told us that when they themselves are looking for fresh water when camping, they seek out these Brolga 'holes' and they dig deeper and find where fresh water is seeping off the land” (Bentinck Island is 5km away, the indigenous people of Bentinck also own Sweers Is).

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Nests and eggs

Brolga nesting is well-known from studies on the Vulnerable south eastern population, plus just two studies in the north [3]. Walkinshaw [4] gives a summary: nesting is not colonial, each pair defends a nesting territory up to 300ha, containing one or several wetlands [5]. Both sexes build the nest. It may be just a scrape in the ground but more usually, is a platform of grasses and other vegetation as wide as 142cm across, with a water ‘moat’ to 50cm deep. There are 1-3 (mostly 2) eggs, 95mm x 60mm, weighing 170-195g. Both sexes incubate, hatching is in about 30 days. Chicks leave the nest and can swim at only 1-2 days old.

[3a] JG Blackman (1978). The swamps in ‘Exporation North: Australia's wildlife from desert to reef’, ed HJ Lavery. Richmond Hill, Vic: 147-183.
[3b] GW Archibald & SR Swengel (1987). Comparative ecology and behavior of eastern Sarus Cranes and Brolgas in Australia Proceedings of the 1985 Crane Workshop, ed JC Lewis: 107-116 (Download this reference from Ozcranes Downloads»)
[4] LH Walkinshaw (1973). Cranes of the world. New York, Winchester.
[5] JD Arnol et al. (1984) ‘Management of the Brolga (Grus rubicundus) in Victoria’. Technical Report Series. Melbourne, VIC, Victoria Fisheries and Wildlife Service, Dept of Conservation, Forests & Lands

Brolga eggs Brolga turning eggs

Brolga eggs, SE Australia: courtesy Mitch Reardon. Brolga turning eggs, NSW: (P Merritt)

Brolga nest video

Adrian Martins of the North Central Catchment Management Authority (Victoria, Australia) has posted amazing Brolga nest footage. For full screen viewing see the YouTube version.

More Brolga nest, egg and chick images on Ozcranes: here» and here». External sites: More nesting Brolga images on Peter Merritt's site.

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Development

Both parents feed, brood and guard the young, which are fully-feathered at around 13 weeks and can fly soon after. They stay with their parents for up to 11 months until the next breeding season, and develop full head and leg colouring over the next 2-3 years. Brolgas pair at 3-4 years, and first breed successfully when 5 years old; they form long term pair bonds. View image of immature flightless Brolga with parent»


Next: Brolga FAQ 3 | Habitats and behaviour»

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