I know many of us have foul words for the polar vortex pattern this winter. While weather definitely does influence our feathered friends I’m not going to focus on meteorology today. During waterfowl season a hunter harvested an unfamiliar bird to this region, a Longtailed Duck (for more about this duck see A Different Bird Indeed post). Earlier this week a couple of birders and the weekly area waterfowl survey accounted for another member of the waterfowl family that also spends its summers on the arctic tundra wintering at Duck Creek Conservation Area.
Three to five tundra swans were spotted at different times on Pool 2 in the flooded moist-soil vegetation. This is not the only location in Missouri where tundra swans have been seen this year. In northwest Missouri, there have been sightings at Squaw Creek National Wildlife Refuge earlier in the fall and more recently a couple were recorded on Bob Brown Conservation Area. In mid-Missouri there has been a group of tundra swans on Binder Lake just west of Jefferson City. Finally, just north of St. Louis there have been a few tundra swans mingled in with the hundreds of trumpeter swans on the wetlands surrounding the Riverlands Audubon Center. While the species for other reports is unknown, other groups of swans have been recently seen on the Missouri River west of Booneville, at Swan Lake National Wildlife Refuge, and on multiple farm ponds scattered throughout the Ozarks. It seems like quite a winter for swan sightings across Missouri.
So what makes this a grand occasion or something notable? Well, although tundra swans are North America’s smallest member of the swan family, they are the most numerous. The eastern breeding population estimate is large enough at approximately 100,000 birds that they can handle a degree of hunting pressure. Folks in the Central Flyway in Montana, North Dakota and South Dakota along with hunters in the Atlantic Flyway in North Carolina and Virginia can partake in a swan hunt administered through a permit system.
If tundra swans are abundant enough to hunt in some states, why is a sighting here big news? The eastern tundra swan population’s breeding range extends from the northern slope of Alaska to the eastern side of Hudson Bay in Manitoba. Typically, we think of waterfowl pretty much migrating straight north and south within a single flyway (see the Bird's-Eye View post). This isn’t the case with tundra swans. They use the North American landscape a little bit differently. As they head south out of the tundra and cross the boreal forest, their fall flight takes a southeasterly trajectory. As the hunting regulations indicate, these birds cut across the northern prairies of the Midwest and then fly over the many small and Great Lakes of the north. At this point, most of the birds head almost due east and end up on the Mid-Atlantic coast. Ninety percent of the population typically winters on the brackish estuaries of the Chesapeake Bay in Maryland and south to the Pamlico Sound of North Carolina; hence the reason for the hunting season. A recent study from the University of Western Ontario, which tracked the movement of 63 tundra swans with satellite transmitters between 1998 and 2012, showed that there wasn’t much deviation from the flight plan, and these birds pretty much stick to this narrow corridor that sweeps across the northern part of the U.S.
However, if you think about it there are still about 10,000 birds that deviate from the course for one reason or another and winter someplace else. We know that the distribution of wintering goose populations can shift over time and we have seen this year that freezing temperatures and ice will definitely move mallards and other dabbling ducks south. Thirty years ago a tundra swan sighting in Missouri would definitely have been rare event indicating that a bird definitely was off course. In the last five to 10 years, these occurrences seem to have increased a little bit. They still may have strayed from the original plan, but groups of 3 to 30 birds now can be occasionally found on the inland, freshwater wetlands of Missouri. Whether this is a dramatic shift or just part of the inherent flexibility of birds using what they can to survive, I can’t really say. What I think is cool, and hopefully you do too, is that these animals have the capacity to adjust and can utilize habitats that are a little off the beaten path.
Now, there might be a few folks out there wondering why the Mississippi Flyway doesn’t allow swan hunting if the Central and Atlantic Flyway do. I mentioned trumpeter swans earlier in the post. Unlike the tundras, trumpeters are our biggest species of swans, yet they do not have nearly the numbers of their smaller cousins. Historically, the range of breeding trumpeter swans was widespread through the interior part of the nation, and many would winter in freshwater wetlands along the Mississippi Alluvial Valley and tidal wetlands along the Gulf Coast. This species however was on the brink of extinction in the early 1900’s and it has been a long road back to recovery. Successful restoration efforts have taken place in Minnesota, Wisconsin, Ontario, Iowa, and Nebraska to establish a self-sustaining population that totals almost 10,000 birds to date. In recent years we have begun to see these birds re-establish their migration patterns and have witnessed them pioneering new wintering locations within their former range. These numbers are still really low, and the regulations are there to protect these species and ensure that hunters don’t mistakenly harvest trumpeter swans .
From a distance, tundras and trumpeters are both big white birds. However, they can be differentiated by sight and sound. If you have scope or binoculars, you may be able to tell a difference by the shape and color of the bill. Tundra swans may have a small yellow patch on the side, whereas trumpeters do not. Another characteristic is at the top of the bill. A trumpeter has pointed “widow’s peak,” while the “hair line” on a tundra is more rounded or straight across. One other visual clue is the trumpeter swan’s straight line from the base of the bill up to the eye. On a tundra swan this line is more curved and the eye is more distinct from the bill.
The audible difference between the two species can be attributed to the lengths of their vocal cords. The trumpeter swan has longer loop in its windpipe and therefore much like a trombone, it has a low pitched honk. The smaller tundra swan’s call is higher pitched and more similar to the hooting or baying of Canada Geese.
Both species are rather remarkable in my book. One starts in the tundra and takes a path less traveled by other species, which typically doesn’t include Missouri on the itinerary. The other is slowly building its way back from the ledge of extinction and gracefully reclaiming the habitat that it called home over a hundred years ago. Although it is easy to complain about cold hands and blustery winds this season, if you can find a swan or two on one of Missouri’s wetlands, perhaps that will bring a little warmth to your heart despite the low mercury.
I'd like to thank Allen Gathman and Danny Brown for their photo contributions. The tundra swan photo was from Duck Creek and the trumpeter swan photo was taken at Riverlands.