When I think of terns, I usually think of ocean shores, but there is one beautiful little tern that is found across the United States and Canada on small fresh water inland ponds, especially on prairie sloughs: the black tern.
This little tern is different from most terns by not being white with various markings. It is instead a dark gray bird with a black head in breeding plumage. They are not abundant in most places, but almost every small inland pond has its pair of black terns. I remember asking my late husband Bill one day why I had never seen one at Evergreen Lake for it seemed like a perfect place for them. He replied that he had also wondered the same thing for he had never seen one there either.
We finally decided they might not come that far into the mountains and/or it could be because the wetlands are often too dry. At any rate, this spring brought 11 black terns to the lake in late May migration. They were seen by Loie Evans, and one was seen later the same day by Karel Buckley.
Black terns nest at such places east of Denver as Barr Lake and Bonny Reservoir as well as into the lakes of the sandhill country of Nebraska and on into the central plains of Canada. They were common nesting birds on small ponds and marshes in western New York, and we knew them well when we lived there. Their gray mantle often reflects the sunlight, so that they appear to be silver.
Black terns have a very buoyant erratic flight as they turn and dip to pick up food from the water. Their gray back and wings with black head and breast are unmistakable in breeding plumage, but the first-year birds have a white head with black markings. They are not breeding yet and often wander about in small migratory flocks. The only similarly colored tern is the sooty tern, which is only found in the far southeastern states and the Caribbean region. They are saltwater birds of the ocean shores.
Black terns build their nests on cattail marshes and grassy marshes where the nests are placed on last year’s debris just at water level. In some cases, they are actually floating on the surface. They usually build in an opening in the cattails or in grassy areas where access is easier. Black terns are very protective of their nests and will dive bomb anyone who comes close. They do not dive into the water for food from the high above as most terns do, but drop from just a few feet to scoop up food.
It will be interesting to see if now that some young birds have visited the lake, if they will return in future years to nest. Although the wetlands were reconstructed at Evergreen Lake after they dredged the lake to make more storage room, they were reconstructed a bit too high and therefore are often too dry. It is also possible that the warming trend in May makes the higher altitude more desirable, and they may move into Evergreen Lake rather than moving farther north as many birds are doing.
Another unusual bird at the lake in late May was a pair of bobolinks, which appeared on Saturday, May 21. This is not a new record for the lake, since a small flock appeared there several years ago and stayed most of the morning, so many birders had a chance to see them. These grassland birds had migrated all night and were tired, so they stayed around, resting and feeding on the golf course.
However, not finding any tall grasses, they were perched in a young ponderosa pine looking totally out of place. However, they are common nesters in the prairies north of us in Canada, and they left the next day.
Bobolinks are handsome birds, especially the males in their black, white and cream breeding plumage. As I have said many times, one never knows what may be seen in May, so it is well worth being out every day this month. If you can spare the time, you may see totally different things at the lake in the afternoon or early evening than you did in the morning. That is why birders refer to it as the Magical Month of May, when anything can happen.
Spring migration is about over for this year, but it won’t be long before early fall migrants start moving south. These are usually unmated birds, which are often in incomplete plumage and are difficult to identify.