Throughout much of the United States the racer is abundant and is one
of the snakes best known to man. Its active diurnal habits and its
preference for a habitat in meadows, pastures, and hayfields rather
than in remote wilderness areas, result in frequent encounters with
humans. The racer is a predator on many kinds of small animals, both
vertebrates and invertebrates; it takes as food chiefly animals that
are agricultural pests but also destroys some beneficial kinds. Yet,
in general, the attitudes of rural people toward the racer are little
influenced by these economic and ecologic considerations, but rather,
are dominated by an unreasonable fear, despite the racer's inoffensive
disposition, and inability to inflict any harm on humans.
Although an extensive literature exists regarding the racer, no
thorough study of the species' natural history has been made
heretofore. Obviously such study is needed. Few species of vertebrates
having comparable economic bearing have been similarly neglected. In
1948, undertaking a program of ecological research on the recently
created University of Kansas Natural History Reservation, I included
the racer among the many common species studied to gain insight into
the functioning of the local ecosystem. Live-trapping of snakes on the
area was begun in 1949, and these operations were greatly intensified
in the years 1957 through 1962, with efforts concentrated on the study
of the racer in the 1960, 1961 and 1962 seasons. Thus my study is
based upon 14 consecutive years' records on the Reservation, the
northeasternmost section in Douglas County, Kansas, six and one-half
miles north northeast of the University of Kansas campus at Lawrence.
After the acquisition in 1956 of the 160-acre Rockefeller Tract
adjacent to the Reservation on the north in Jefferson County, field
work was extended to this new area, which, because it was superior
habitat, in the final years of the study produced more records than
the Reservation. An important but relatively minor segment of the data
originated from Harvey County Park, 13 miles west of Newton, Kansas,
where lines of live-traps were maintained in 1959, 1960, 1961, 1962.
Smaller collections of data were obtained from the Lalouette Ranch in
the Flint Hills, three miles northeast of Florence, Marion County,
Kansas, and from Cedar Bluff Reservoir, 23 miles west and seven miles
south of Hays in Trego County, western Kansas, where live-trapping was
carried on in 1959 and 1960. Additional data were obtained on
numerous field trips to various collecting localities in northeastern
Kansas. My first-hand knowledge of the species is also based, in part,
on many years of field experience with the far western subspecies _C.
c. mormon_ in western Oregon and California, and on similar experience
in 1947 and 1948 with the southern subspecies, _C. c. anthicus_ in
central Louisiana.
This varied field experience with the species at localities well
scattered throughout its geographic range has added perspective to the
study even though most of the records were collected within a radius
of three quarters of a mile. No one locality can be regarded as
entirely typical of a species' habitat over its range as a whole.
According to my philosophy, the ecological niche of a species is
subject to geographical variation analogous to the variation to be
seen in the morphological characters of the animal itself. Different
community associates, including different competitors, prey, and
predators, and different physical factors enforce a somewhat different
way of life on a species in geographically remote parts of its range.
When analyzed these differences often turn out to have a genetic
basis. Thus, limits of tolerance to heat, cold, and drought often vary
geographically, and the population density, reproductive potential,
seasonal cycle, and other properties of populations may be altered
either by the direct effect of the environment, or through its effect
on the genetic constitution, produced by natural selection.
The local population of racers studied was near the center of the
species' geographic range, and is to some extent representative of the
species as a whole, though differing in its ecology from other
populations in proportion to their remoteness and the distinctness of
their habitats. It has not been demonstrated that ecological traits of
populations change in a discontinuous manner or correspond in their
limits with those of named subspecies. More likely geographical
variation is continuous and parallels morphological variation only in
a general way. Certainly the boundaries of subspecies' ranges should
not be accorded undue emphasis in an ecological study.
My investigation of the blue racer under natural conditions, combined
with a compilation and analysis of published literature, has resulted
in a fairly satisfactory understanding of some phases of the species'
ecology and natural history, such as the food habits, the growth rate,
the extent of home range and of seasonal movements. However,
relatively little was learned concerning some phases of the life
history. Unfortunately, the traps used did not catch young of the
smaller sizes. Facts concerning egg-laying, incubation, and hatching
therefore are known chiefly from snakes kept in confinement. Although
first-year young were captured by hand from time to time they were
obtained in relatively small numbers, and little was learned regarding
their population density, movements, or mortality factors. Of course,
such hiatuses are to be expected; even in man such enigmas as the
disparate sex ratio still challenge the investigator.
For the subspecies of racer involved in my field study the widely used
vernacular "blue racer" has been adopted in this report. In general I
advocate conformity with the vernacular names published by the
Committee on Herpetological Common Names (1956). However, in this
list, the name blue racer was assigned to _Coluber constrictor foxi_,
an invalid subspecies of the Prairie Peninsula that has been relegated
(Auffenberg, 1955:92; Smith, 1961:196) to the synonymy of _C. c.
flaviventris_. It therefore seems appropriate that the book name
"yellow-bellied racer" applied to _flaviventris_ by the Committee
should be abandoned for this subspecies, and that the name blue racer
be applied officially, as it is in actual practice by both laymen and
herpetologists, to all populations of this subspecies.