Sass Factor 5: American Coots

If you are an animal, spring usually means it's time to get your breeding on. Coots are no exception, and they're particularly visible when it comes to reproductive madness. GW Gullion, whose paper on coot displays I also read, has another paper on the red bump of coots. Apparently most migratory coots don't have one during winter, when they are away from their home territory:

But in spring, the testosterone of both males and females sparks the growth of a reddish callus:

...which can get gigantic and menacing.

I took all these coot pictures on the same day. So, why do they have different sized bumps? Gullion says that the most dominant coots--those defending a territory--are the ones with the biggest bumps, and the others are lower on the pecking order. Some coots stay on a territory year-round, and keep their red shield, too. I am wondering, do coots on Lake Merrit have a territory? Do they actually nest there? They are supposed to prefer freshwater. I've never seen a baby coot at the Lake. What are they defending if not nest sites? Are they just testosterone fueled jerks that will fight regardless?

Gullion also argues that coots may recognize each other by the callus, as well, since sometimes they will try to fight their mates until they see their partner's face.

Next time I'm out I'll see if I can compare the faces of the attacking coots and the fleeing coots.