May 2021 Natural Mystery Answered

Kirsten points out that the curved toes point to this being a webbed track, which narrows our options down considerably. Mike notes that “Trumpeter Swan tracks range from 5 3/4 to 7 inches, and are webbed tracks. Other swans have similar tracks, but playing the odds in Minnesota, I would vote for Trumpeter Swan.”Indeed, we regularly see trumpeter swans throughout the Metro, including all winter long on Snelling Lake. Tundra Swans migrate through in spring and fall, and Mute Swans are occasionally spotted in the park, but trumpeters are much more common. Most other webbed bird tracks are all much smaller. Kirsten notes that “Canada Geese are often seen on Eagle's Landing. However, their tracks top out around 4 3/4” in length.” Turkey and crane tracks also top out at under 5” long, and show straight toes.

Kirsten and Bill note that eagles and our largest herons can leave tracks that measure over 6” long, but that these tracks have straight toes and include a long hallux.

Bill notes that there is one other webbed bird track in this size range that shows curved toes and that is the totipalmate track of the pelican. But he points out that the “pelican’s hallux is usually about half the length of other 3 toes. Toe 1 (hallux) on this track is not close to that size. The hallux on a swan is very short and sometimes it does not even show the track.”

But in this case, the hallux does show. This also helps us identify the side. As Mike notes, “the slight angling of toe 1 towards the right indicates this is the left foot.”

We can also identify this as a left track by looking at the length and curvature of the two outer toes. Like other birds, waterfowls have two toe bones in toe 2, three toe bones in toe 3, and 4 in toe 4. Toe In the curved tracks of ducks, geese and swans, toe 2 is not only shorter, but also bends in only a single spot. Toe 4 is longer and often appears more smoothly curved. The sharp bend at the single joint in toe 2 is clearly visible in this track, contrasting with the gentle curve of toe 4.

Congratulations again to Bill, Kirsten and Mike for identifying these swan tracks. And thanks to everyone who submitted an answer--and to everyone who simply enjoyed looking at the mystery and reading what our friends had to say about it :)

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