Northern Minnesota phenology report: October 2010

Trumpeter swans in Monticello MN by Nina Hale

Mist and fog obscure the far shore of the lake. Closer in the maples glow a faded red and yellow through the haze. On the water not a ripple stirs the surface. Ghosting out of this surreal scene are several large white birds. Are they trumpeter swans, or their cousins the tundra swans? My first impulse is trumpeters, they are native to the area and the flock is small. In early October it seems too early for the migrating tundra swans.

Trumpeter swans were re-introduced to Minnesota in the 1960’s after having been extirpated in the late nineteenth century. In the 1980’s the Minnesota DNR began raising and distributing trumpeter swans. In 1995 the first swans were released in Itasca, St. Louis, and Becker Counties. Now fifteen years later the population is over 2000 birds and more are being raised every year. Where once it was not necessary to try to determine whether it was a tundra swan or a trumpeter swan now there are large populations of both.

The tundra swans will move through northern Minnesota in large flocks. Those that pass this way are headed to the Chesapeake Bay area. We see them spring and fall as they migrate. Their summers are spent in the far north. Some tundra swans may go to Siberia to breed and raise their young. Any swans seen in the summer months around here are by default trumpeter swans. In the fall and spring however the two are often found on our lakes and ponds, so how can we tell them apart?

The tundra swans are smaller. The average weight of a tundra swan is about fourteen pounds while the trumpeter swans tip the scales at a whopping twenty-three pounds. Unless you happen to see them side-by-side the size comparison is difficult. Wing span can be definitive with the tundra swans measuring roughly five feet and the trumpeter swans closer to seven, but these numbers are meaningless if they are not seen together. That’s not very likely. Could that be a trumpeter swan, or is it a tundra swan just a bit closer to me? It’s a bit like trying to tell a raven from a crow.

Tundra swan by Flickr user gdahlman

Seen on the water and perhaps with the aid of binoculars there are a few subtle differences that can be observed. Perhaps the most obvious is the presence of yellow on the bill of the tundra swan. About 50% of the population has a bit of yellow on the bill near the eye. Looking over a flock might reveal this tell and this is the most obvious of the signs though not always present. If you have binoculars and a steady hand look at the border between the bill and the feathered portion of the head. Seen from the front on the tundra swans this transition is a rounded arc, while on the trumpeter swans it’s more of a widow’s peak, a bit like Eddy Munster’s hairline. Seen in profile the feathers along the tundra swan’s bill appear to bend near the mouth, or gape, as it is called. On the trumpeter swans the feathers at the gape form a smooth curve.

With the exception of the yellow on the bill these are all tenuous divisions. The most obvious clues I employ are timing, location, and flock size. Early spring just after the ice goes out the tundra swans are in the area and heading north. They are often seen in large flocks, twenty or more birds, and they frequent large lakes. The trumpeter swans come back even earlier and in some cases never leave. The Mississippi River is home to many trumpeters all winter. When the trumpeters do come back the flocks seem to be family groups of five to ten birds and they are likely seen on small ponds and open water around the edges of lakes. The tundra swan migration in the fall is dramatic. Large flocks sweep through the area as the waterfowl seasons come to a close. Many a waterfowler marks the end of the season with the arrival of the tundra swans. The trumpeter swans steal quietly out of the area as small family groups, and as I mentioned, some merely re-locate to a river that promises to remain open through the winter. Perhaps positive identification is not the real issue. It may be enough to know that once again both of these large, all white birds can be observed across the northland.

John Latimer is well known throughout northern Minnesota for his phenology work. He appears weekly on KAXE radio in Grand Rapids.

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  1. Yesterday I say a young swan go by my window. I live 4 miles north of Finland
    and we still have 2 feet of snow. Was this last years young? It was small and I know what it was, and even second guessed myself and looked up a picture of
    a young swan and sure enough, that is what I saw!! i’m along ways from any open water. What gives?