Last week’s column focused on studying and differentiating the tracks of rodents: mice, voles, rats, chipmunks and squirrels. This was a group that I had largely ignored when I first developed an interest in wildlife track and sign, and was drawn to the large mammals.Another group of animals whose tracks I regularly walked by in the field without pausing was the birds. Back in 2008, New York State Parks piping plover steward Latisha Coy taught me to recognize the subtle tracks of the endangered shorebird, and what the various track gaits meant in terms of their breeding and nesting behavior. Since then, several other colleagues have prompted me to learn to identify the tracks of other native birds.
You might wonder why someone would bother learning to recognize the footprints and track patterns of an animal that, unlike many of our mammal species, is easily observed during daylight hours. First of all, there are a surprising number of bird species—and not just gulls—that leave tracks at the beach and the water’s edge of coastal ponds and bays, and these substrates leave excellent track impressions that are easy to find for beginner trackers, including children.
Second, the study of tracks is an excellent discipline to hone your general nature observation skills, and will make you a better all-around naturalist.
Third, it’s a lot of fun!
The photos accompanying this column were chosen to illustrate some of the variety of bird tracks you will commonly encounter on the beach and shore here.
One of the first things that you’ll want to note is the number arrangement of the toes. Most birds have four toes arranged with one toe protruding toward the rear and three toes pointing forward, as shown in the photos of crow and heron tracks. Crow tracks are surprisingly common on our ocean beaches. Two of the three forward toes are very close together, while the third splays out by itself. The latter is the outermost toe on the foot, so you can easily tell the left from the right among this group (the photo shows the track of a right foot).
American crow and fish crow tracks range from 3 to 3.5 inches in length, while common raven tracks measure 3.75 to 5.25 inches long. Measurements are taken from the tip of the longest front toe to the tip of the rear toe, and include claw marks.
Note the asymmetry of the heron track, where the rear toe is slightly offset and does not line up directly behind the middle of the three forward toes. Great blue heron tracks are the largest of this group at 6.5 to 8.5 inches long, but the track shape is very similar for all the members of this group: snowy egrets, great egret and the night herons.
Birds that spend most of their time on the ground, including the shorebirds and game birds (e.g. plovers, killdeer, turkeys and quail), either lack a rear toe or the rear toe is so short that it often does not register. Among this group, the toes are generally splayed out quite a bit as shown in the photo of the piping plover track.
The largest track in this group around here is the wild turkey, measuring 3.75 to 5 inches. Note that because this group often does not register (or have) a rear toe, the measurements are taken from the claw of the longest toe to the rearmost edge of the foot pad where all toes converge, called the metatarsal pad.
Of course, you will encounter lots of bird tracks with webbed feet at the beach, tidal flats and shorelines of ponds and creeks. The thin webbing found on our wide assortment of gulls, ducks, swans and geese does not always register clearly. A webbed foot is more reliably determined by the shape of the outer toes, which are noticeably curved due to the webbing pulling them inward.
Notice the asymmetry of the cormorant prints, where the outermost toe is longest and the rear toe claw mark points to the side. All four toes in this species are connected with webbing, an adaptation for greater underwater propulsion to catch fish.
For those of you interested in studying bird tracks, the best reference book is Mark Elbroch’s “Bird Tracks & Sign.” And while you are out in the field, don’t forget to note other clues to the presence of bird species, such as pellets. Bird digestive systems include a crop where sand, small pebbles and other hard grit grind up food items. Among the predatory birds, fur, fish scales, feathers, bones and other indigestible items are regurgitated in the form of a compact pellet, instead of being passed on down through the remainder of the digestive system.
Pellets, particularly those coughed up by owls, are interesting to poke through to determine what was on the dinner menu during the night.