April 2022 Natural Mystery Answered

We received a wide range of answers to last month’s Natural Mystery, with guesses spanning four different orders of birds--which may not be surprising, since this bird's taxonomy has been in flux for decades. Congratulations to Bill Kass who correctly identified both what bird and which foot left this track.

This is the right track of a Turkey Vulture, Cathartes aura.

I’ll turn it over to Bill to explain how he identified this print:

"This track appears to be about 4 or 4 1/2 inches in length. Several birds that might be found on a dirt road in this area fit this size: Sandhill Crane, Turkey, and Turkey Vulture.

Toe 1 on this track (hallux) does not seem to clearly register and toes 2 and 4 are noticeably short as compared to toe 3. The angle between toes 2 and 4 seems to be a little less than 90 degrees and all three toes seem "hefty".

Sandhill crane tracks have much larger angle splay between toes 2 and 4 (closer to 180 than to 90). The angle and this being on the large size for a crane and very hefty toes does not lead me to believe this could be a Sandhill Crane.

Turkey tracks on the other hand, have tracks that are about 90 between toes 2 and 4 and hefty toes. Often the metatarsal pad shows up clearly and there is space between the toes and the pad. I do not see these characteristics in this track.

The angle is less than 90 degrees between toes 2 and 4. The toes seem connected to the metatarsal pad. Toe 2 seems a little shorter than toe 4. But the most significant feature that leads me to not think these are turkey tracks are the very long toe 3.

These features all fit very nicely for a Turkey Vulture though!"

Exactly right. Along with other Western Hemisphere vultures, Turkey vultures leave distinctive tracks that may look surprisingly similar to those of their namesake, the Wild Turkey. Like turkeys, the vulture’s hallux is raised on the leg and typically registers either as just a claw mark if it shows at all. The distinctive characteristic of their tracks, as Bill notes, is their proportionally long Toe 3.

Bill skipped explaining how he identified this as a right track. Turkey Vultures follow the typical pattern of Toe 2 being slightly shorter than Toe 4 – a difference that is clearly visible in this photo.

Turkey vulture tracks have been classified as “Classic” bird tracks by some authors, but many trackers consider them “Game Bird” tracks. Since our bird track classifications are based on the form of the track, not the taxonomy of the bird, I agree that they should be considered “Game Bird” tracks. Turkey Vultures have the reduced, raised hallux that defines the group of “Game Bird” tracks. And their tracks are most likely to be mistaken for those of turkeys.

It turns out that it’s not just their tracks that have proven challenging to classify. Turkey Vultures and their close kin been reclassified several times. Some 20th century authorities thought these scavengers were closely related to storks, based on physical and behavioral characteristics (including both the structure of their feet and a habit of defecating on them to cool off). Early genetic work suggested they could be grouped together with falcons, but more recent genetic studies place them in their own order, Cathartiformes (after the genus name of the Turkey Vulture), which is a sister group to the hawks and eagles.

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