by Bryce W. Robinson
I think one of my favorite birds is the Black Tern- Chlidonias niger. They are visually striking birds, and their habits are equally intriguing. I remember last summer, making my way down through Canada, bound for the border, then Chicago. Once I hit southern Saskatchewan, the land became scattered with small ponds and marsh lands. It was a lush scene, full of birds. They call these scattered bodies of water on the high prairie the prairie potholes. They are the remnants of the last glacial maximum, and now are home to multitudes of waterfowl, and birds alike.
Black Terns are common in this part of North America. One afternoon, I pulled over at a small pond, where a group of Black Terns were coursing the sky, feeding on the open water. I watched their behavior for some time, and soon realized that they were feeding young, somewhere hidden in the reeds. I could hear the juvenile birds begging. It was impossible to locate a bird. They were simply too deep, safe in the marsh.
At this time of the year, some of the terns had already started their pre-basic molt. It interested me that not all of the birds in the flock had started molting. I know very little about the molt cycle of the Black Tern, but this variation between individuals stuck with me.
I hope to find myself watching Black Terns again, sometime in the late summer this year. If I do find a few, I’ll be paying attention to their plumage, the date, and what aspects might be influencing their individual molt timing. I’m sure someone like Steve Howell, who has studied the various molt strategies between taxa, and knows a thing or two, could offer some insight.