New records and a review of animal foods in the diets of the Brolga Antigone rubicunda and Australian Sarus Crane A. antigone gillae

Abstract

Cranes are opportunistic omnivores, sometimes considered to be primarily vegetarian. However, there is limited knowledge in Australia of their animal prey and its importance in their diets. From field records in 2006–2021, we report novel foods including fish and crabs taken by adult Australian Sarus Cranes Antigone antigone gillae and the first records of the foods of their dependent young (crabs and grasshoppers). For Brolgas A. rubicunda, we report the first records of ducklings as prey, and of crabs, beetles and grasshoppers fed to dependent young. Both species have learnt to prey on rodents displaced or killed by sugar cane harvesting machinery in northern Queensland. A review of diet records since 1810 also reveals some overlooked foods and food-handling methods but, despite a sighting of a Brolga ingesting a whole Cane Toad Rhinella marina, there is no evidence of immunity to the toad’s toxin in either species of crane. The plant and animal components of the diet of the dependent young of both species remain almost unknown and there are also significant knowledge gaps for the animal prey of adult Australian Sarus Cranes; the vertebrate prey of adult Brolgas; and the balance of prey types for both species in the breeding and non-breeding seasons. To advance knowledge of crane diets and nutritional ecology in Australia and New Guinea, direct field techniques including faecal sampling, collection of shed feathers and camera trapping could be undertaken, supported by remote electronic technologies in relatively inaccessible breeding wetlands. Meanwhile – in anticipation of the forthcoming revision of the Handbook of Australian, New Zealand & Antarctic Birds – we urge fieldworkers, birdwatchers and others to examine their field notes for unpublished information on crane foraging and food items, especially for the dependent young of Brolgas and Australian Sarus Cranes.