April 2019 Natural Mystery Answered

For our April Natural Mystery, I'd like to send out a special thanks and congratulations to Terry Hunefeld. Terry sent in the first correct identification of these tracks and offers us several helpful pointers in his answer. Terry is also our newest sponsor on Patreon, joining at the River Otter level. Thank you for your support of the newsletter and these Natural Mysteries, Terry! Congratulations also to Kirsten Welge and Rob Grunewald who also submitted correct answers this month. I'll let the three of them take it from here:

Terry offers us the following breakdown of the tracks:

Game bird track. Somewhat asymmetrical with partial webbing between toe 3 & toe 4. The feet are turned inward (pigeon-toed) unlike similar-sized quail tracks but characteristic of plovers. The bird is walking (thereby excluding birds that hop). Metatarsal pad registers lightly on the right track, not at all on the left. Track length 1.25" Width 1 3/8"

Similar species eliminated:

Sandpipers and dunlin would register a hallux.

Piping and Semipalmated plovers are smaller.

Conclusion: Killdeer

And indeed, theses are Killdeer tracks. As Rob notes in his answer, few of us in Minnesota were tuned in to the nuances of shorebird tracks on our fist evaluation back in April of 2016, but we all learned a lot that day, and in the years since. Rob echos Terry's points in his own answer, noting:

Compared with sandpipers, killdeer tracks are more asymmetrical, trails are more pigeon toed, and tracks do not register toe 1, whereas sandpiper tracks reliably register toe 1.

Kirsten shares these points in her answer as well, while offering some additional refinements. Regarding the asymmetry of the tracks, she notes that "There is a greater angle between toe 2 to toe 3 (about 85 degrees), compared to toe 3 to toe 4 (about 45 degrees)." The roughly 45º and 90º angles Kirsten describes are fairly distinctive and can be used as a quick (though not foolproof) diagnostic for Killdeer. Kirsten also digs into the range maps and migration timelines to point out that the plovers and dunlin would be extremely rare to see in mid-April in Minnesota, whereas Killdeer are becoming a common sight.