- «Cranes |
- «Brolga FAQ1 |
- Brolga food & water
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. On this page we present the first photographs of a Brolga eating birds' eggs, recently (August 2020) published in Australian Field Ornithology. Helen Dunne took the photographs while watching birds at a dam on a central Queensland grazing property.
Due to a specialsed gland, Brolgas are the only crane able to drink saline water, more on Ozcranes here». Brolga FAQs 1 covers features, size, location and numbers and an introduction to Brolgas and Sarus Cranes including comparison photos and calls, is in Ozcranes Australia/New Guinea Cranes Intro.
Food
← Brolga feeding on eggs of Australasian Grebe (arrowed). The previous egg swallowed shows as a bulge in the Brolga's neck (image by Helen Dunne, central Queensland). This is the first record of a crane in Australia preying on birds' eggs.
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. 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].
← Brolga feeding crab to juvenile, Gulf Plains (Tim Nevard). The ground – a dried up wetland – was concrete hard, but adult Brolgas prised open cracks with their strong bills, to dig up crabs
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 sorghum seed 58%; 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 species, 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 Brolga]...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].
TOP
↑ L: Brolga eating crab (Tim Nevard). 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).
Water
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, see Ozcranes page on Brolgas and salinity».
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 and wading. Above: uprooting waterlily tubers, Double Lagoon, Gulf Plains far NW Queensland (Tim Nevard»).
Below left, wading in St Lawrence wetlands, central Qld (gillbsydney).Below right, Brolga drinking at watering puddle in tourist park garden, Broome, WA (Lesley Parker).
Websites and videos
- Tony Ashton Blog: Brolga catching a dragonfly and Brolga taking rat killed by cane harvester
- 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)
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.
Next: Brolgas and salinity» or Brolga FAQ 2 | Breeding»
« Back to Brolga & Sarus Crane Introduction
_-_Flickr_-_Lip_Kee_(6).jpg){kind=link}