What Made This Track?
Monday, October 15, 2001
Copyright © 2001 Gary Valle'. All Rights Reserved.
Tracks, Simi Hills
The most common tracks I see on
trail runs are the footfalls of people, dogs, and coyotes.
But anything that moves, or is propelled across the ground
can make a track.
If you look closely, interspersed between the myriad of
hiking boots, running shoes and fat tires are some unique
and interesting tracks.
Some less common tracks are fairly easy to identify. For
example, this sinuous track in sandy soil was
clearly made by a snake. But others,
especially when first seen, can be quite bewildering.
Even when the basic identity of a track is
known, there are other questions that can be asked. In the
case of this snake track, two questions come to mind. What
kind of snake made the track? What direction was the snake
The most common snakes seen in the area are rattlesnakes.
A mature rattlesnake moving slowly in sandy soil makes a
"squeezed out of tube" track suggestive of a heavy-bodied
snake. Another snake seen on this trail is the Striped Racer.
Racers are fast, narrow-bodied snakes with a more direct,
streamlined track than a rattlesnake. A young rattlesnake
was found further down the road, and my guess is that this
track was also made by a young rattler.
Snake Track, Simi
It appears the snake's direction of travel was right to
left. As the snake progressed across the road, some small
hummocks were used to propel the snake forward employing
a combination of lateral undulation and concertina progression.
For more info on snake locomotion see: Vertebrate
Locomotion (D. Ingold)
Scratch Marks, Simi
What animal made these numerous
scratch marks? You may have seen dogs wipe or scratch
their feet after relieving themselves, but these fastidious
scratch marks are reminiscent of a feline's
"cat box" behavior.
Len McDougall, in The
Complete Tracker, comments that "Unlike those
of a cougar, which most often scratches from the direction
it departed, bobcat claw marks tend to be from all directions..."
In this close-up of the claw
mark in the foreground it appears the forefoot was expanded
in typical feline fashion as the cat dug in its claws. If
it was a bobcat, it was a fairly large one, with a forefoot
width of perhaps 2.5-3.0 inches.
In April of 2000, while running in the Simi
Hills, northwest of Los Angeles, I came across this very
strange track. In the following days there was an explosion
of these tracks over
a dispersed area of perhaps four square miles.
Leafing through my references, the first hint was gained
Guide to Animal Tracks. Further investigation suggested
the tracks were probably made by a Western Spadefoot Toad
(Spea hammondii) whose preferred habitat is grassland, scrub
and chaparral. The drag marks are typical of tracks in soft
sand and point toward the direction of travel.
This Spring (2001) there were very few of these tracks, so
it seems that environmental conditions results in varying
populations from year to year.
Simi Hills (CA)
Simi Hills (CA)
Some tracks are just plain bizarre... These
were scattered across a sandy fire road. Reminiscent of the
overlapping tracks of a covey of quail, the incongruous tracks
suggested a pattern, but I couldn't quite put my finger on
the type of pattern.
After my experience with the toad
tracks almost anything seemed plausible. Searching
the area the
culprit (an uprooted Mustard) was found just a few
Reading tracks reminds me that something cannot exist without
affecting its surroundings. The effects may be so tenuous
as to be nearly imperceptible, or so catastrophic as to be
immeasurable, but interaction in some form is a prerequisite