Life History and Ecology of the Five-Lined Skink, Eumeces fasciatusFitch, Henry S. (Henry Sheldon)
Science
Life History and Ecology of the Five-Lined Skink, Eumeces fasciatus
Fitch, Henry S. (Henry Sheldon)
Eumeces fasciatus
Ontogenetic change in the color pattern is of significance in connection
with the secretive habits. The red facial suffusion of the breeding male
renders him more conspicuous in his natural surroundings, but this
bright color is ephemeral. It is developed as a warning, for display to
other males. Otherwise, in the adult male the color of dull brown is
inconspicuous in its natural surroundings, usually against a background
of leaf litter, dead stems, and soil. In the juvenile the contrasting
pattern of dark brown ground-color, five longitudinal light stripes, and
a vivid blue tail, is far more conspicuous. The young skink might seem
to be handicapped in its chances for survival by this conspicuousness.
However, in snakes it has been shown that a vivid striped pattern,
characteristic of forms that are fast moving and live in dense
vegetation, serves to conceal motion, and aid its possessor in confusing
and eluding pursuers. The young skinks, being far more active than the
adults, may use the striped pattern more effectively in this way. Often
when a young skink is startled in its natural surroundings, and takes to
cover, the observer does not see its outlines at all, and is conscious
of it only as a flash of blue. On many occasions, while walking in the
woods, I have had my attention attracted by a faint rustling of dry
leaves, and have received such a fleeting impression of the flashing
blue tail as to be uncertain whether or not I had actually seen a skink,
until, raising a flat rock or other shelter, I found that one actually
was present, concealing itself in the nearby hiding place. The erratic
movements of a frightened skink that is warm and fully active, make it
exceedingly elusive. With sudden lashing movements of its heavy tail and
hindquarters, it may flip its body about, facing first in one direction
and then in another, as it pauses before or after a rush for shelter.
The sudden reversals of direction are so confusing to the pursuer that
the skink may often escape by hiding after a few seconds of pursuit,
even though the situation provides no shelter where the lizard is
entirely secure. The tail-flip described is characteristically given at
the instant the lizard reaches shelter such as a crevice, or hole, and
just before it disappears. By the instantaneous pivoting of its body,
throwing its tail in an arc, in the direction of its original course,
the lizard creates the optical illusion of having moved beyond the point
where it has taken to shelter. The peculiar writhing movements of the
tail of juveniles that are moving about in the open accentuate the
conspicuousness of the vividly colored tail, and suggest that this
conspicuousness may be advantageous to the lizard in serving as a decoy
to catch the attention of predators and distract them from the lizard
itself.
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