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
Blue racers tend to limit their activities to familiar areas or home
ranges; some individuals may live out their entire lives within the
same home range, but others shift from time to time. Average home
ranges of approximately 26 acres for males and 24 acres for females
were calculated. The racers' preference for hibernacula in a habitat
different from that to which summer activities are confined
necessitates spring and fall migrations between the limestone outcrops
where hibernation occurs and the grasslands where the snakes stay in
summer. The average spring or fall migration is approximately a
quarter of a mile, but an individual racer does not consistently
return to the same hibernaculum. Many racers were recorded to have
made movements of 2000 to nearly 4000 feet, involving shifts in home
range, but some later shifted back to their original areas. Some may
have made even longer shifts but their movements would not have been
recorded since they would have gotten beyond the limits of the study
area.
Blue racers hunt by various methods, often by coursing through dense
vegetation in active search in which vision is of primary importance
in locating the prey. Almost any small animal that moves nearby may be
overtaken and caught with a sudden dash. From analysis of scats and
prey from stomachs, a total of 1357 food items of more than 50 species
was compiled. Favorite prey species were the cricket (_Gryllus
assimilis_), grasshoppers (_Arphia simplex_, _Melanoplus
femur-rubrum_, _M. bivittatus_, _M. differentialis_), camel crickets
(_Ceuthophilus_ sp.), katydid (_Neoconocephalus robustus_), vole
(_Microtus ochrogaster_), white-footed mouse (_Peromyscus_ sp.),
racerunner, (_Cnemidophorus sexlineatus_), and leopard frog (_Rana
pipiens_). The insects taken greatly outnumbered the vertebrates, but
the vertebrates made up most of the actual bulk of prey eaten.
Crickets, grasshoppers, and katydids comprised most of the insect
prey. Beetles, moths and cicadas were rarely taken. Vertebrate prey
included miscellaneous small snakes (some of them juvenal racers),
mammals, and birds. Seasonal change in the composition of the food is
slight, but vertebrates figure more prominently in early summer, and
insects comprise increasing percentages later in the season.
Composition of the food differs according to size of the snake;
gryllid and ceuthophilid crickets are best represented in the food of
juveniles whereas small mammals, and grasshoppers of the genus
_Melanoplus_ are best represented in the food of large adults.
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