Brolga food and water

On this page Ozcranes looks at Brolga foraging, food items and water. Brolgas are omnivorous, eating many foods, but foraging behaviour and food items in some regions are still not well-known. Due to a specialsed gland, Brolgas are the only crane able to drink fresh or saline water, but there are no published studies of Brolgas drinking in the wild to describe or quantify this. Here we present a description and photographs of Brolgas apparently drinking salt water on Sweers Island, Gulf of Carpentaria, north-west Queensland.

Brologa FAQs 1 covers features, size, location and numbers. An introduction to Brolgas and Sarus Cranes including comparison photos and calls, is in Ozcranes Australia/New Guinea Cranes Intro.


Food

Brolga probing tubers

← Brolga digging for tubers, Northern Territory (Geoff Whalan)

There are several ways to determine foods eaten by cranes. Direct observation (including photography), either opportunistic or in a planned study; to examine gut contents (from specimens, i.e. freshly-killed birds); and by analysing faeces or moulted feathers. From observations we know that 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]. On the Gulf Plains breeding grounds, analyses of moulted feathers showed that Brolgas are more omnivorous than Sarus Cranes, taking a wider range of tubers and invertebrates [2].

Brolgas and crops

Brolgas have been persecuted (poisoned or shot) due to crop damage, when they pull up new grain seedlings to eat the germinating seed (see Ozcranes Crane Hazards 2» and Cranes on Farms 1»). Due to perceived crop damage by birds in the Ord Irrigation Area, Western Australia, P N Gowland undertook a 4-year study from 1977 to 1981. As well as recording feeding activities and habitats of various birds, amongst other specimens he collected 54 Brolgas and examined the stomach contents [3]. He found 58% sorghum seed; river grass seed (a weed in rice paddies), 11.8%; rice seed 9.6%, maize seed 7.1% and peanuts 5.7%. Animal foods were 6.6% including grasshoppers, spiders and snails. Brolgas also ate the northern army worm, an important rice crop pest. Nevertheless he concluded that crop damage by Brolgas was very minor in grain crops overall. Like other crane speces, Brolgas also eat grit and pebbles to help grind up tough foods. This was first noted by the explorer Edward Kennedy, who wrote:

On dissecting the Grus antigone...the stomach was exceedingly thick and muscular and contained large pebbles in great proportion, seeds of the swamp grass, Coleoptera (beetles) and what appeared to be vegetable matter generally [4].

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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). R: Brolga probing for bulbs, SE Australia (P Merritt).

Brolga hunting in mud Brolga probing for bulbs

↓ Maximum water depth for large wading birds is accepted as equivalent to full leg level. These images show the maximum observed depth of water for Brolgas feeding (Double Lagoon, Gulf Plains far NW Queensland, Tim Nevard») and wading (St Lawrence wetlands, central Qld (gillbsydney). See also image at top of Sidebar. Below, Brolga drinking at watering puddle in tourist park garden, Broome, WA (Lesley Parker)

Brolgas hunitng in deep water
Brolga wading Brolga drinking puddle

Websites and videos

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Water – fresh and saline

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. Images of Brolgas ‘scooping up’ and swallowing water are in the Sidebar. 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 [5] 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 apparently drinking sea water.

Brolgas drinking seawater Brolga footprints Brolgas on  beach

↑ L. Brolga family drinking seawater, and C. their footprints on the beach showing the three front toes. R. Brolgas feeding on the beach, Sweers Island, far NW Qld. Their salt excretion gland (see left) enables Brolgas to drink salt water and feed in saline environments (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).

References

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

[2] KSG Gopi Sundar, John DA. Grant, Inka Veltheim, Swati Kittur, Kate Brandis, Michael A. McCarthy and Elinor C. Scambler. 2019. Sympatric cranes in northern Australia: abundance, breeding success, habitat preference and diet, Emu 119: 79-89.

[3] Gowland, P.N. 1983. The Ecology and Management of Waterbird Pests in the Ord River Irrigation Area, Western Australia. RAOU Microfiche Series, No. 35. RAOU, Melbourne.

[4] Chisholm, A.H. 1944. Birds of the Gilbert diary. Emu 44: 131-150.

[5] 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.

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