Pacific Reef Egret fish sorting behaviour?
By Yeo Seng Beng.
On Sunday 7th October 2018, at 5 pm in the evening, I observed a Pacific Reef Egret (Egretta sacra) dark morph catching fish at low tide off Singapore’s West Coast Park. The egret was positioned where a large monsoon drain with a continuous flow of water connects to the sea. I suspect small fish congregate here because the drain water carries food into the sea.
As it was low tide, the sea was quite shallow, and the egret easily caught 4 fish during the 25 minutes that I was observing it. What was interesting was how the bird handled the fish, depending on the size of the fish.
The smallest fish, the egret ate immediately.
The largest fish, which the bird was unable to hold on to, escaped within a few seconds.
But the 2 intermediate sized fish, the egret surprisingly did not eat straight away, but placed the fish on dry land up on the bank of the monsoon drain, presumably to wait until the fish became less active.
In the meantime, the egret would return to the sea to catch more fish. But if the fish it left on dry land, started to flip or jump too vigorously, the egret would return to the bank to check on, or watch over these fish.
Unfortunately, I did not have time to wait to see what the egret finally did with the fish it left on the bank, but one assumes after all the hard work to catch and monitor the fish, the egret would eventually eat the fish as delayed gratification!
Here is a 3 min video demonstrating how the egret handled the 4 fish it caught.