On two separate occasions, Dr Chua Ee Kiam encountered an injured Purple Heron (Ardea purpurea) at the Sungei Buloh Wetland Reserve:
“I managed some shots of this Purple Heron on two occasions and I thought that something had pierced its lower jaw until a frontal shot of it opening its mouth revealed that its lower jaw was torn (pierced and torn by a wriggling catfish’s spines?) and a flap of tissue dangled from its lower jaw. This is like a patient having its trachea cut to allow him to breathe.”
Birds that feed on fish like Black Bittern (Ixobrychus flavicollis), Stork-billed Kingfisher (Halcyon capensis) and Great-billed Heron (Ardea sumatrana) need to knock off the fish and then position it in such a way that it can be swallowed head first. This will ensure that the spines will not damage the birds’ throat.
In the case of this Purple Heron, it is possible that it was trying to swallow a catfish, as suggested by Ee Kiam. The strong, sometimes serrated dorsal and pectoral spines can tear a bird’s throat as seen here if, not handled correctly.
Kelvin P K Lim of the Raffles Museum of Biodivertsity Research, National University of Singapore has this to say: “I think that heron must’ve been really careless to have been damaged this way. I’ve seen pictures and footage of herons eating large catfish, and it must be a very common food item for them. However, this is the first time I’ve seen a picture of a heron with a torn throat. Catfish spines are really strong and thick and I believe they can cause that kind of damage, but I really cannot confirm if the bird in the picture was hurt by a catfish.”
Input and images by Dr Chua Ee Kiam, additional input by Kelvin P K Lim.