Diverse Divers

A male bufflehead starts to dive under water at sunset

Visit Ridgefield in the winter and you’ll see waterfowl diving under the water to feed, such as this bufflehead at sunset above, or the coot below, its red eye visible just above the water. I like to sit and watch them and have been struck by the many differences in the bodies of coots and diving ducks, even though they both spend much of their lives diving underwater to feed. There are differences in their bills, and their feet (ducks having fully-webbed feet, coots not), but my favorite difference is most visible when they dive.

An American coot starts to dive under the water, its red eye visible just above the surface of the lake

Both diving ducks and coots spring forward and break the surface tension of the water with their beaks, but ducks leave a vortex behind them at the start of the dive while coots do not, a difference that begins with their ends. Diving ducks like the bufflehead have broad tails that they spread out horizontally on the water before they dive, enabling them to push their tails down and themselves forward as they start their dive. You can see the pattern of their tail feathers, shown below as water flips off the bufflehead’s tail as he finishes the dive, in the water behind the duck in the first picture.

A male bufflehead's tail flips water as he dives under the water

Compare the bufflehead’s tail above to the coot’s below and you’ll see the coot has a stubby little tail and can’t use it to push forward like the diving ducks can. While it might seem that the diving ducks have solved the diving problem much more efficiently than the coots, I should point out that the coots at Ridgefield far outnumber any species of diving duck at the refuge.

The tail end of an American coot's dive

A trait they share in common is that they have to get a long run across the water to take to the air, so if a bald eagle attacks, they prefer to dive under the water as a means of escape. It’s usually effective, but sometimes you’ll see an eagle keep flying over a duck or coot repeatedly until its prey tires and surfaces at just the wrong moment and is captured in the eagle’s talons. I’ve seen eagles with a variety of waterfowl in their talons, but coots more than any others, not surprising given their large numbers.

Constant Movement

A group of American coots feeds in an open area of a frozen lake

A cold snap at the end of 2014 left many of the ponds and lakes at Ridgefield frozen over, but this group of American coots was helping keep a section of South Quigley Lake open with their constant movement as they dove under water in search of plants to eat. There’s a culvert near here that runs under the road and keeps water flowing between the north and south lakes, so the water here tends to stay open longer than the other parts of the lake.

The handful of splashes in the picture are from coots diving under the water, in the splash on the far right one of the coot’s legs is visible sticking up above the water. There’s also a pair of American wigeon on the far right, they frequently will try and take some of the plants that a coot brings to the surface, but on this morning they seemed content to just hang out with the coots and enjoy the safety in numbers as well as the open water. The sun was just starting to rise on this New Year’s morning, there’s a hill above the refuge that blocks the sun right at sunrise but it was just starting to crest the hill and illuminate the trees at the far side of the lake.

Open Water

A flock of coots swims in a tight pack

Coots often hang out in large groups and when it gets cold enough to freeze the ponds at Ridgefield, such as this cold New Year’s Eve morning, the constant movement of the flock helps keep part of the pond from freezing. This not only benefits them, as they dive under the water both to feed and to avoid hunting eagles, but other waterfowl as well, such as the bufflehead who would join them the following morning.

The Ice Walker

An American coot walks across the ice

I love photographing coots, one of the most commonly seen birds at Ridgefield, as I find it fascinating how they do many of the things that diving ducks do yet their bodies differ in many ways. I was shocked the first time I saw their almost comically large feet and was surprised to see that they aren’t webbed like a duck. We had a cold snap to start the year and some of the smaller ponds froze over, leaving the coots a bit exposed as their best defense against an aerial eagle attack is to dive under the water.