Natural History of the Racer Coluber constrictorFitch, Henry S. (Henry Sheldon)
Science
Natural History of the Racer Coluber constrictor
Fitch, Henry S. (Henry Sheldon)
Racer snake
The disparate figures obtained from plotting minimum home range and
from calculating average home range radius are not irreconcilable,
since a minimum home range based on only four or five points would
ordinarily include only a fraction of the actual range. Distances up
to 1500 feet are included in the calculation of home range. It seems
that home ranges often have a diameter of this magnitude or a little
larger, although the estimated average diameter is 1140 feet. Home
ranges probably most often deviate from circular shape to form an
ellipse, with one diameter markedly exceeding the other. Woodland,
water, roads, buildings, or cultivated fields, or other areas that are
unfavorable or uninhabitable often form the boundary of a home range
and influence its shape.
Many of the longer movements constituted clear-cut shifts in range. In
one exceptional instance a large adult female captured in the
northeastern part of the Reservation on June 22, 1950, was released 21
days later at a point 3900 feet southwest of the place of capture. On
May 27, 1960 she was caught within 600 feet of the original location,
seemingly having made a homing movement. Among the nine racers
recorded to have made longest movements (exclusive of those movements
made to or from hibernacula) four were recorded also to have made
later long movements in the reverse direction, probably returning,
each to its original home range, although in every instance the return
movement was somewhat less than the original. A female of two-year-old
size when first captured on September 2, 1957, was recaptured 3100
feet southeast on May 10, 1958. On August 7, 1959, she was recaptured
again 2400 feet from the second location in the direction of the
original capture. Similarly, in a three-year-old female a shift of
2730 feet was recorded at the second capture after 21 months, and at
the third capture 14 months after the second, a return trip of 2360
feet had been made. A second-year female made a trip of 2640 feet
between May 17 and October 1, 1960; by May 1961 she had returned 2000
feet to the vicinity of her original capture. From one year to the
next an adult male shifted 2450 feet; after another year he had moved
back 1550 feet. Most of the longer movements recorded were those
between home ranges in fields and hibernacula along ledges, but in
this class of movements, distance was somewhat proportional to elapsed
time. For 59 such movements exceeding 2000 feet the average was 3.1
years, whereas for 114 field-to-ledge movements of less than 2000
feet, average elapsed time was 1.6 years. This trend suggests that
over periods of years a racer is likely to shift its range or its
hibernaculum or both.
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