Persistent eagle

It was the third time lucky both for the eagle and for me.

Bald Eagles and Ospreys each have a taste for fish. Of the two, the osprey is the better fisher. The osprey can dive into the Lake and bring up a fish through a depth of about a metre. The eagle’s access is far more limited as it stays airborne and merely presses its claws into the water and grabs a fish that is swimming just below the surface. (This difference, along with other larcenous tendencies, often prompts the eagle to try to steal fish from ospreys.)

On Kootenay Lake, there is a problem even getting to see an eagle grab a fish, let alone photographing the sequence. The event can happen anywhere on huge body of water and is remarkably ephemeral: under two seconds from approach to departure. With no way to anticipate the event, how can one possibly know where or when to look, let alone where to point a camera. (Good published shots of an eagle grabbing a fish have usually been taken at a fish farm, not over open waters — those images are spectacular, but a bit of a cheat.) 

However, at sunrise this morning, an eagle twice warned me of its pending fish grab. That was all I needed. I prepared. The first warning came when I saw a surface-skimming eagle drop a fish in the Lake. The thrashing fish was just too big to have been lifted into the air. I grabbed my camera, knowing the eagle would try for it again. 

Despite this warning, I only managed one crummy shot before the eagle again couldn’t lift the big fish into the air on its second try. Would it try again? I would be ready. Alas, nothing happened for ten minutes — presumably the eagle was resting before its next attempt, and the now-battered fish wasn’t going anywhere.

Finally, the eagle tried a third time, and both it and I were now up to the task.

As the Bald Eagle approached the fish’s location, it lowered its legs and claws.

When close to the fish (the white smudge ahead of it), the eagle moved its claws forward. It must dig its claws into the fish and swing its legs back at a much higher speed than it is flying forward.

A quick grab and the eagle and a rather large fish were airborne. Alas, the eagle’s problems had just begun. The eagle raised the fish from the water with a powerful downstroke of its wings. But, it has much less lift on the wing’s successive upstroke, during which time the weight of the fish will again drag it down.

During the wing’s upstroke, the eagle has less lift and so the heavy fish drops back into the water. With the fish back in the water, there is increased drag, which further decreases flight speed, and so also lift. This problem occurred three times until the eagle finally prevailed. In the meantime, the eagle had another problem in the form of a restricted downstroke.

The movement of the eagle’s wings is limited by the surface of the water. So, although the full downstroke should be able to support both eagle and fish, the eagle can make only a half stroke before the wing tips touch the water. The eagle must get well clear of the water before it can successfully fly off with the fish.

Here, the eagle has finished its powerful downstroke and has shifted to its less effective upstroke. It is clear from the adjacent splashes that both wings had entered the water. Fortunately, the bird has lifted high enough this time that the large fish can be seen clearly. It is a largescale sucker.

After two earlier failed attempts to lift the sucker from the water, and then a few struggles during the third attempt, the eagle finally succeeded and was able to fly off with its prize. It might be simpler merely to rob an osprey the next time it is hungry.