Marco Van Brabant writes, regarding Black Skimmers:

What I always wondered was how these birds have the power to run that long lower mandible through the water. I always imagined it causing so much friction that it should be impossible for the bird to zoom it effortlessly through the water.

When we see pictures of these birds looking for their meals, they are usually shot perpendicularly to the path in which they fly. Or when we see pictures of the bird resting, it is almost always also a side view, showing the big red and black bill.

I imagined it to be as wide as it is thick, but I just looked at some pictures I took a while back and realize how it is possible to do it, namely the bill is as thin as a knife and cuts through the water, kinda the same as when you stick you hand out of the car window when driving at high speed: turn the palm of the hand facing the wind and you feel the resistance, turn the palm of the hand down, and there is hardly any resistance left. Bingo, that’s how they do it…

I have some mediocre pictures (because I shot them with a relatively short lens) and one of them shows a little of what I just realized.

(Thanks, Marco!  A few Black Skimmers still being seen…)