Box turtles rely for protection on the closable shell and on
inconspicuousness; defense reactions, except in the rare instances
that biting is provoked, are purely passive.
Box turtles handled in the course of field work varied widely in their
reactions. Many struggled violently when being measured or marked
whereas others were completely passive, closing the shell tightly and
making it difficult for me to examine the soft parts of the body.
These differences in behavior did not seem to be correlated either
with sex or with age; generally lessened activity was associated with
suboptimum body temperatures. All box turtles found in the field were
extremely wary. As soon as one sighted me (sometimes at a distance of
200 feet or more), it became motionless with shell raised from the
ground and neck extended (Pl. 28, Fig. 5). Some turtles remained in
this motionless stance for half an hour or more, finally moving slowly
away if I remained motionless. Turtles made no attempt to escape until
I approached them closely or until they were in danger of being
trampled by my horse; they would then move away with remarkable
rapidity. Box turtles seemed unaware of an intruder until he could be
seen or until he touched the turtle. When a turtle was approached from
the rear, whistling, finger snapping, and normal footfalls did not
attract its attention. Latham (1917:16) observed corresponding
behavior in _T. carolina_. Wever and Vernon (1956) found the ear of
_T. carolina_ to be keenly sensitive to sounds in the range of 100-600
cycles per second but progressively less sensitive to sounds of higher
and lower frequencies. Surely a predator as stealthy as a coyote could
approach a box turtle unseen and could quickly bite off at least one
of the turtle's legs. Many of the mutilated box turtles that I
observed may have survived such encounters with carnivores. The
tendency of some individuals, when handled, to over-extend the limbs
and neck (rather than closing the shell) in an attempt to escape,
would make them easy victims for any predator.
Ornate box turtles were kept in my home, along with several cats.
Initial behavior was characterized by mutual wariness; subsequently
the cats would follow a turtle about the house for a time,
occasionally pawing at an exposed limb. The turtles withdrew only when
touched or when approached from the front. After a day or two the cats
and turtles ignored each other, often eating and drinking from the
same dishes without incident. Under these circumstances the cats, I
believe, could easily have killed or injured the turtles. A turtle
would occasionally gain the respect of a cat by biting it.
The strong odor sometimes given off by box turtles is produced by the
secretions of four musk glands, two situated anteriorly on each side
and opening by small, nearly invisible apertures beneath the fourth
marginal scute. According to Hoffman (1890:9), two other musk glands,
opening beneath the eighth marginal scute on each side, are also
present in _Terrapene_; these posterior glands were not found in the
several specimens of _T. ornata_ that I dissected.
Strong odors were produced by nearly all small juveniles until they
became accustomed to being handled. Older juveniles and adults
produced strong odors only in response to pain or injury, as, for
example, when they were killed in the laboratory prior to preservation
or when they were being marked in the field. Young box turtles were
capable of producing strong odors as soon as they hatched.
Norris and Zweifel (1950:3) considered the odor produced by _T. o.
luteola_ to issue from the "... concentrated, highly pungent
urine...." voided by individuals when they were disturbed, and thought
the production of odor to be a defense mechanism. Neill (1948b:130)
reported that hatchlings of _T. carolina_ with unhealed umbilical
scars emitted a musky odor comparable to that of the stinkpot,
_Sternotherus odoratus_; he thought the capacity to produce this odor
was lost at about the time that the plastral hinge became functional.
The function of musk glands in _Terrapene_ and, in all other turtles,
is unknown. Since biting and nuzzling of the edges of the shell is an
integral part of the courtship of many turtles, odor produced by the
musk glands may well be a means of social recognition or of sexual
stimulation. Repellant odor may have a protective value in young box
turtles but it is unlikely that larger predators would be frightened
away or even discouraged by odor alone. In this respect Neill (_loc.
cit._) and I concur.