Geoscience Reference
In-Depth Information
Flying tracks are by far my favorite of all bird tracks to find, and many other
people must share this feeling, as the more frequently forwarded photos I receive
from ichnologically inclined fans are of these. One of these photos shows a snowy
vista punctuated by repeating sets of four mouse tracks, which end abruptly as they
coincide with the feathered outline of an owl. The tale is all there in the tracks: a
small mouse galloping across the snow, knowing that it is risking its life by being
out in the open; an owl spotting it from its roost, then taking off with a whispery
flap;aglidedownwithtalonsextendingandgraspingthemousejustasitlandedon
the snow; a beat of the owl's wings against the snow surface to continue its forward
momentumandbecomeairborneagain,butthistimecarryingalittletreat.Sadlyfor
ichnologists, though, such detailed and evocative traces are more likely to be made
insnow,which,oncewarmed,hasarudehabitofmeltingandthuserasingallofthe
evidence.
In my experience, the best places to look for flying tracks are in soft mud
or sand along a seashore, lake margin, or river floodplain. While examining these
tracks, watch for the paired ones, and for gaps in their trackway patterns. Nothing
quite says “flight” like a right-left pair of bird tracks with no other tracks in front
of or behind them. Do you see no tracks behind them, followed by a normal track-
way? These are landing tracks. Do you see a normal trackway that ends with two
tracks, and nary a track after that? These are take-off tracks. Other details to note in
such tracks are linked to whether a bird was trying to control its descent or begin
its ascent. For instance, in landing tracks, birds with rearward-pointing toes (digit
I) on each foot direct these forward, leaving long claw-marks while “putting on the
brakes.” As the other forward-pointing digits contact the ground, these will push
against the mud or sand, forming mounds in front of those digits as the entire foot
comes to a halt. For take-off tracks, these reveal whether a bird left the ground in-
stantly—with a burst of wing-driven power, it is aloft—or needed a little more for-
wardmomentum,suchasarunning,skipping,orhoppingstart,aidedbymuchflap-
ping. In such trackways, distances between the sets of tracks become greater, re-
