Waterbirds catch and release a poisonous fish at a mudflat in southeastern Australia

Abstract

Several waterbird species prey on fishes, and usually use only one sensory mode to detect this prey: herons hunt visually guided, whereas ibises mostly search tactilely guided. I report herein events in which a heron and an ibis caught and released a poisonous fish at a mudflat in southeastern Australia. A Great Egret (Ardea alba) that targeted small gerreid fishes caught and immediately released the very toxic pufferfish Tetractenos hamiltoni, with bill washing and discomfort movements afterwards. Two Australian White Ibises (Threskiornis molucca) that probed for bottom-dwelling fishes and crabs caught and handled these pufferfishes for about 60 s, before releasing them. Next, the birds dipped the bill in the water and resumed hunting. Pufferfishes are rarely preyed on by birds, but an Australian bird that feeds on this fish type is the Silver Gull (Chroicocephalus novaehollandiae), which eats the pufferfish Torquigener pleurogramma when it is nontoxic or less harmful.