By Alan OwYong and Steven Wong.
This pair of Grey-headed Fish Eagles, Ichthyophaga ichthyaetus, are raising a family somewhere at the Toh Tuck area and have been fishing along the Pandan Canal for some time now. Both or one of them will perch in the mid canopy of the Albizia trees by the side of the canal either in the early morning hours or late afternoons looking out for any signs of life in the canal.
Perched up in the mid canopy, looking down at the canal waiting for any movements in the water.
Many of the dives and catches have been well documented in a number of great action photos posted in various Facebook groups recently. All of them show them diving down from the perch and snatching a fish from the surface of the water before taking it back to the trees.
Steven Wong’s photo of the Sea-eagle entering the water with both wings up. I had a photo of the eagle completely underwater with only the ripples to show on the surface. But deleted it off hand as it had nothing to show.
But on the morning of 21 March 2019, Steven Wong and I witnessed a dive catch we have not seen before. The eagle dived into the water and caught a catfish that was swimming beneath the water surface. At one stage the whole eagle was submerged under the water only to reappear out of the water like from out of nowhere.
Struggling to get up after being fully submerged in the water.
To do this, the eagle must have an extremely sharp eyesight to see the catfish that was swimming well below the surface. Maybe the clearer water that day helped. Then it must continuously keep track the movement of fish as it was diving down from the perch.
Relieved to have both wings clear of the water.
The hardest part must be when and where to plunge in as the fish was below the surface. It will first have to allow for the parallax as the fish was not where it is looking from above. It will also have to allow for the evasive action of the fish in the split second after it hit the water surface.
It takes a lot of down force to lift off judging from the turbulence on the water surface, captured in this photo by Steven Wong.
After hitting the water the eagle will not be able to see the fish as its nictitating membrane will cover its eyes. It will depend on its speed, trajectory and self belief that it talons will somehow fall on to its target and grab it. It was interesting to see that it managed to grab hold of the catfish head instead of mid body. It must be aiming for its head right from the start so that it will still get the other parts of the body if it miscalculate the strike. This hunting technic must have been learnt from the many failures in the past.
Determination written all over its face as it tried to drag it catch off the water.
Reversing its flight after the catch had to be another feat of power, using its wings to stop it going deeper and then pushing it back up to the surface. From the shots it took the eagle quite a few second to get airborne partly due to the size and weight of the catfish. We were happy to witness this hunting behaviour and add to the knowledge of these fish eagles in our midst.
Success and food for the chicks today. It will eat the top half of the fish on the Albizia tree before taking the tail end back to the nest.
Aiming for the head gave the fish eagle some margin of error.
Many thanks to Steven Wong for spotting the eagle that morning and generously sharing his local knowledge of the hunting behaviour of this pair of Grey-headed Fish Eagles.