by changes in seasonal distribution of food, shelter and other
requirements, causing them to abandon certain areas and invade others by
gradual stages, without venturing far, at any time, into unfamiliar
surroundings. Occasional individuals apparently get lost and undergo a
period of wandering before they re-establish a home range. An individual
venturing slightly beyond the border of its home range might lose its
orientation and fail to return, especially if it left under conditions
of stress, as when pursued by an enemy, or a rival of its own species.
Several individuals originally captured in the vicinity of the quarry or
nearby ledges, were subsequently recaptured at the pond rock pile more
than 200 yards away. In these instances it may be that the lizard
wandered from its home range along the ledge, and finding itself in
thick woods, with nearly continuous canopy permitting insufficient
sunlight, and with few rocks for shelter, it continued down the slope to
the lower edge of the woods, crossed a ditch, and a 100-foot stretch of
grassland, and finally reached the exceptionally favorable habitat
provided by the rock pile.
The extent to which memory persists through the season of dormancy is
little known, but great change takes place in the habitat during the
colder half of the year when the lizard's activity is suspended. Even if
the area is one that is free from gross disturbance by man or large
animals, the changes occurring are so great that the area might be
scarcely recognizable from the lizard's viewpoint. Herbaceous vegetation
mantling the soil, at the height of its development in late summer, will
have died, dried out and the leaves and stalks will have been matted
down by wind, rain, and snow, and incorporated in the surface layer of
soil by the next spring. Shrubs and trees having shed their leaves,
present contours quite different from those in autumn. Holes and
crevices familiar as avenues of escape, will have been sealed, by the
weather collecting and compacting surface debris. Less extensive changes
are involved in the occasional blowing down of trees and dead snags,
erosion of gullies, deposition of sediment and drift wood, and
disintegration of logs. Many of the invertebrates which are the main
food sources in late summer, are unavailable in early spring, being at
different stages in the life cycle or annual cycle of abundance; and
those kinds which make up the bulk of the spring diet likewise are often
unavailable in fall. These changes in location of food supply, shelter,
and other needs, and the seasonal change in microhabitat, breaking the
established routine of conditioned responses to habitat features would
seem to promote shifts in range after emergence from hibernation. The
available records tend to bear out this supposition. Of the 15 skinks
recorded as making long movements of more than 250 feet that almost
certainly involved shift in range, only one was recaptured the same
season; the other fourteen had passed one or more hibernations.
In the course of the study approximately 30 individuals were released or
accidentally escaped at places other than the locations where they were
originally taken. Some of these were young hatched in the laboratory,
some were of unknown origin, their locality tags having been lost before
release while they were being handled in the laboratory, or escaped from
defective cloth bags while they were awaiting processing or release, and
some taken on remote parts of the Reservation or nearby land were
deliberately released on one of the study areas with the idea that they
would replace skinks of the same sex and age, recently eliminated
through an accident of trapping or handling. Ten were released in Skink
Woods, ten at the pond rock pile, eight at the laboratory building, and
two near Rat Ledge. In no instance was a transferred skink known to have
found its way back to an original home range, although some might have
done so with fairly short trips of only a few hundred feet, and the
chances of recapturing them would have been good. Therefore it seems
that homing instinct is either wholly lacking or but feebly developed.
The incidence of recaptures was low, only four for the entire group,
suggesting a tendency to wander away from the area of release before
settling down on a home range. One young found on May 11, 1950, in the
laboratory where it probably had escaped, was released in Skink Woods,
and was recaptured three times in the summer of 1951, in what seemed to
be a home range within 80 feet of the point of release. Another young
of unknown origin released in Skink Woods on May 18, 1950, was
recaptured six days later 160 feet away. Five hatchlings from a clutch
of eggs incubated and hatched in the laboratory, were released in Skink
Woods on August 8, 1952. The following April two of them were
recaptured, only 20 feet and 25 feet respectively, from the point of
release. The movements and dispersal of this group from the point of
release probably paralleled that of a typical brood dispersing from its
nest after hatching under natural conditions. An adult male captured
just off the Reservation was released at the pond rock pile on May 15,
1952, and was recaptured there on June 2 and June 4. In general, skinks
transferred from their original location seem soon to settle down in a
new range if the habitat is favorable, but establishment of a home range
may or may not be preceded by an initial period of wandering.
Food Habits
McCauley (1939:151) examined contents of 25 alimentary tracts of _E.
fasciatus_ collected in Maryland as the basis for the most extensive
account of the food habits yet published. One tract contained a broken
_Eumeces_ tail, possibly that of the lizard that ate it, which had a
recently broken stump tail. A half-grown skink contained numerous
_Eumeces_ scales, and McCauley interpreted this as indicating that it
had fed on another of its own species or of _E. laticeps_. As no other
hard parts of the assumed victim were in evidence, these scales may have
been the lizard's own slough. (In the present study it was found that
eating of the slough was far more frequent than cannibalism.) Arthropod
prey included: 11 orthopterans (4 undetermined, 3 unspecified
grasshoppers, 2 gryllids, 1 blattid, 1 acridid); 10 coleopterans (7
undetermined, 1 each of rhynchophoran, cerambycid, carabid, staphylinid
larva, elaterid adult and larva); 8 spiders; 5 pulmonate snails; 5
flies; 3 undetermined; and one each of lepidopteran larva and adult,
ant, dragonfly, thysanuran, and sow bug.
In Ohio, Conant (1940:31) noted food items consisting largely of
grasshopper nymphs and small beetles. He found that in captivity these
skinks would eat mealworms, crickets, grasshoppers, spiders, roaches,
and newborn mice, and a few individuals would lap egg from a mixture of
chopped meat and eggs. One large male killed and ate a small common
swift (_Sceloporus undulatus_). Netting (1939:162) mentioned newborn
mice, birds' eggs and small lizards as possible prey, although stating
that this species is mainly insectivorous.
Taylor (1936:61) describing the feeding habits of lizards of this genus
wrote: "The food consists of a very extensive variety of insects and
insect larvae, Arachnida and occasionally small crustaceans. In a few
specimens traces of plant material have been observed, but I regard this
as being most probably of accidental introduction in the diet. Probably
the most surprising fact about the diet of the forms examined is that
ants are absent." In the present study of _E. fasciatus_, the trends in
general bore out Taylor's findings concerning absence of ants from the
diet, although three ants were found among more than 600 other food
items. These three, one of them a larva, were of the two largest species
among the many kinds of ants found in the area of the study. Most of
these local kinds of ants are below the minimum size of prey ordinarily
taken by the skinks. Colonies of small ants, _Aphenogaster_ sp., for
instance, are abundant in the soil beneath flat rocks in the same
situations where the skinks are found, and constitute most of the food
of the small toads, _Microhyla olivacea_, which were abundant in the
same habitat and microhabitat as the skinks, especially in the Skink
Woods study area (Freiburg, 1951:383).
Burt (1928:56) without citing specific records, stated that "The food of
_E. fasciatus_ consists largely of insects and spiders," but in another
paper (1928:62) he listed contents of two stomachs, including a wood
roach (_Parcoblatta_), a cricket (_Gryllus pennsylvanicus_), a
grasshopper, and 2 spiders (attid and lycosid). Smith, summarizing the
findings of other authors (1946:350), stated that "The food consists of
various small insects, insect larvae, earthworms, spiders, etc. Small
vertebrates such as young lizards and mice are sometimes eaten." In a
later work Smith (1950:188) altered this statement slightly: "The food
consists of almost any small moving animal, including many kinds of
arthropods and even small vertebrates."
Many authors have mentioned predation on mammals by these skinks, but
without citing specific instances, which must be rare indeed, for the
smallest newborn mice seem to be near the maximum size of objects that
could possibly be swallowed by the largest adults of the common
five-lined skink. Various early records and statements pertaining to
predation on small vertebrates by five-lined skinks probably pertain in
most cases to _E. laticeps_, which is much larger than _E. fasciatus_,
and more powerful.
Barbour (1950:102) recorded stomach contents of an _E. fasciatus_
collected in Harlan County, Kentucky, as consisting of 60 per cent
Arachnida, 30 per cent adult Lepidoptera, and 10 per cent ants, by
volume. Werler and McCallion (1951:250) mentioned that on two occasions
these skinks in Virginia were seen to eat tenebrionid beetles and
larvae.
Webb (1949:294) fed captive skinks with field crickets (_Gryllus_) and
noted that the lizards tended to seize them by the pronotum, and then
worked forward to the head, chewing vigorously to disable them. The
seized crickets attempted to defend themselves by striking the lizards'
faces and eyes with the cerci and tibial spines. Webb also offered his
skinks newly hatched snails, _Helix aspersa_, which were noticed and fed
upon when they moved. In one instance, he noted that a skink found a
quiescent snail, and swallowed it after testing it with the tongue a few
times.
McIlhenny (1937:232) has published a remarkable account of observations
on the foraging behavior of a large adult male skink (stated to be _E.
fasciatus_ but almost certainly _E. laticeps_) in southern Louisiana,
which climbed among vines on the side of a house and attacked nests of
wasps, _Polistes pallipes_ and _P. bellicosus_, shaking out the larvae,
pausing to crush and swallow the few adults that lit on it and
attempted, unsuccessfully, to sting. After many larvae had been shaken
to the ground the skink descended and made a leisurely search, eating
them in seemingly prodigious quantities. Several times it climbed back
into the vines to shake out more larvae, and each time retrieved from
the ground those it could find. After feeding to repletion it returned
to its habitual shelter in a hollow live oak fifty feet from the house.
In a two-week period, however, it returned frequently to raid the wasp
nests in the vines, and eventually it had attacked all of the 32 nests
that were originally present, completely destroying many of them.
In the course of the present study direct observations on the food
habits of skinks rarely could be made in the field. Most of those seen
had been alarmed by the presence of the observer, and already had begun
a dash for shelter. Others not sufficiently alarmed to take cover, were
affected by an observer's presence, so that usually they ceased their
normal activities and crouched attempting to conceal themselves or
slithered nervously from one vantage point to another, on the alert for
any sign of danger.
On September 1, 1951, a young skink (30-35 mm. snout-vent length) was
discovered on the cement walk just outside the laboratory building,
holding a cricket (_Nemobius_) which evidently it had just caught. When
I came out of the building, the skink, alarmed, ran about ten feet,
holding the cricket by one leg. The cricket was still alive but was
nearly immobilized, except for twitching of its antennae and mandibles,
and evidently it had already been shaken and battered. After maneuvering
about the cement walk the skink ran through the open door into the
building. Though seeming to be uneasy at my proximity it was still
mainly intent on subduing and swallowing its prey. Following, I caused
the skink to take alarm. It dashed back through the door to the walk
outside and still carrying the cricket, it ran along the walk to the
steps leading up to another building and climbed onto the first step
where its uneasiness soon subsided. The cricket was remarkably large in
proportion to the skink itself, being of approximately the same
diameter, with a length nearly half that of the skink's snout-vent
length. Nevertheless, in about five minutes the skink had swallowed it
entire. As swallowing began, on the cement step, the skink was in bright
sunshine of early afternoon. In less than a minute it seemed to become
overheated, and dragged the prey back several inches into shadow. While
swallowing was still in progress, it again ran forward till its anterior
half was in sunshine, seemingly regulating its body temperature by these
frequent shifts.
A similar encounter between a larger juvenile and a cricket
(_Ceuthophilus_) was observed on May 9, 1953. After I had stood for
several minutes beside a rock ledge in woods, my attention was attracted
by a rustling sound in dry leaves. The skink, emerging onto the ledge
from a cavity beneath exposed hackberry roots had its head raised high
and was darting about, peering into crevices and examining its
surroundings with unusual animation. After several seconds the cricket
hopped into view. Possibly it had been injured already, as it moved
deliberately, with short hops. Instantly the skink darted in pursuit,
following its erratic course persistently, as it made several hops. In a
few seconds the skink caught the cricket, bit it vigorously, and
battered it against the rock ledge with violent lateral shaking. Several
times the cricket was knocked from the skink's jaws, but each time it
was quickly retrieved. In a few seconds its struggles were subdued, but
the skink continued to worry it, dropping it and retrieving it dozens of
times. The skink seized the cricket by one of the large rear legs, which
was snapped off with a sudden vigorous shake. The skink then dropped and
lost the detached leg, and ran back to seize the cricket again. The
performance was repeated with several other legs and the antennae, until
most of the appendages were eliminated and the body was softened by
continued biting and chewing. Then although the cricket was of body
diameter almost as great as the skink itself, the lizard swallowed it
head first, engulfing it with violent gulping movements. After the
front end of the prey had entered the gullet, muscles of the throat and
neck were brought into play in forcing it farther down. Swallowing
movements were snake-like, the lizard turning its head at right angles
to the body to squeeze the morsel down.
At the pond rock pile on May 7, 1952, a small adult male was watched as
it moved about over the rocks. A lycosid spider (_Pardosa lapidicina_)
carrying an egg sac was basking on an inclined rock surface. When the
skink had come within a few inches, it made a sudden rush at the spider
which escaped easily. As this common rock-living spider can move with
almost incredible speed, skinks probably do not often catch them in the
open.
Captive skinks, in taking their food, seem to rely much less than some
other lizards on movement of the prey as a means of detecting it. An
active and hungry skink often failed to notice a spider or insect moving
about on the opposite side of the terrarium a foot or more away.
However, on many occasions, skinks moving about the terrarium and coming
upon a motionless prey item have been seen to stop and examine it
intently for several seconds, then grasp it, often in a tentative and
hesitant manner, after testing it with the tongue. Sight and scent seem
to be about equally important in prey recognition, each supplementing
the other, and often functioning simultaneously. As many of the animals
preyed upon are secretive and would seldom be found in the open by day,
it seems that much of the prey is found in hiding places--in leaf litter
on the forest floor, beneath flat rocks or at their edges, and in chinks
and crannies of decaying logs, stumps, and tree trunks. Some of the prey
animals taken are of types that are more active and swift than the
skinks themselves. Presumably the olfactory sense is the more important
in detecting prey that is motionless or concealed. Stebbins (1948:202)
studied the nasal structure of _Eumeces_, and compared it with that of
other lizards. He concluded that the extensive mucus-secreting and
olfactory surfaces suggest relatively efficient humidification of
inspired air and efficient olfaction in lizards of this genus. In
captivity five-lined skinks thrived when provided with ample moisture
and shelter and food and kept within the proper temperature range. The
reactions of these captive skinks to various small animals introduced
into their terraria provided clues as to their food preferences, but
also were misleading in some instances. On many occasions hatchlings and
young of various sizes were kept with adults of both sexes and
subadults, but no instances of cannibalism were ever recorded in
captivity. No hostility was seen except between adults, mainly in the
breeding season. Young of the little brown skink, _Scincella laterale_,
kept with adult _E. fasciatus_, and small enough to be eaten by them,
likewise were unmolested. Small snakes such as _Diadophis_,
_Carphophis_, and _Storeria_ placed in terraria with the skinks evoked
no strong reaction. Occasionally mild avoidance reactions were aroused
but the skinks were never seen to display any hostility and readily
became accustomed to such cage mates. Mealworms, the most readily
available food for the captive skinks, were generally accepted by those
that were hungry and sufficiently warm, but were taken with little
enthusiasm. They were seldom noticed unless the skinks were within a few
inches. Skinks sometimes tested them with their tongues and examined
them intently then moved away without eating them. Earthworms, offered
on several occasions, were not eaten. Harvestmen, seemingly of the same
kind as those found in scats, were ignored by some captive individuals
and taken by others but with some signs of distaste. Ants were ignored.
Scarabaeid beetles, that seemed small enough to be eaten, were attacked
unsuccessfully, as they were too heavily armored to be crushed in the
skinks' jaws. Wasps (_Polistes_) placed in terraria were avoided, as
were carabid beetles and reduviid bugs. A spider placed in the terrarium
usually aroused one or more skinks to animated pursuit, as soon as it
moved. Even spiders that seemed to be too large to be swallowed were
sometimes pursued and attacked. Occasionally freshly killed prey was
taken, especially spiders and wasp larvae. Of invertebrates minute forms
are not taken, while certain ants, and various others of the kinds of
insects most common on the study areas and often found rather closely
associated with the skinks and using the same shelters, were never
represented among the recorded food items. Carabid beetles (_Brachinus_,
_Calosoma_, _Lebia_, _Harpalus_, _Pasimachus_), and reduviid bugs
(_Melanolestes_, etc.) seemed to be especially abundant and available,
but habitually avoided possibly because of their noxious qualities.
Diptera were entirely absent from the sample in the present study--they
and many other insects are so much quicker than the skinks that
ordinarily these insects cannot be caught. Foliage-living insects and
those that are strong and persistent fliers, are rarely available as
prey.
A total of 738 food items were recorded in the present study. Arachnids
with 360 items, and insects with 319, together made up 92 percent of
these food items. There were 334 spiders (most were not definitely
identified, but four were thomisids, 40 were lycosids, and 79 were
salticids, the latter group including 27 of the genus _Phidippus_); 26
harvestmen (_Leiobunum vittatum_ and others); 149 orthopterans (51
ceuthophilid crickets, 31 gryllid crickets, 27 tettigoniid locusts; 17
unspecified, 14 roaches, 9 locustid grasshoppers); 80 indeterminate
insects; 39 beetles (mostly carabids and scarabaeids within a narrow
size range); 19 larvae (13 lepidopteran, 2 coleopteran, 1 ant, 3
indeterminate); 2 ants (_Camponotus herculaneus_ and _C. castaneus_); 2
wasps; 1 moth; 1 centipede; 59 snails (31 indeterminate, 18 _Gastrocopta
armifera_, 8 _Retinella electrina_, 1 _Strobilops labyrynthica_, 1
_Hawaia minuscula_); 23 sloughed skins of the skinks themselves; 2 skink
eggs; and 2 skink hatchlings.
This sample is based on combined sets of data from analysis of stomach
contents and of "scats." The two sets of data present somewhat divergent
trends, and perhaps neither is adequately representative of the food
habits in the geographic area represented. A total of 620 food items
found in scats represented an average of 1.67 items per scat, whereas in
80 stomachs containing food the average was 1.44 items per stomach. Of
the skinks killed and dissected more than half had empty stomachs. Many
of them were, however, found inactive in shelter so that it was obvious
that they had not foraged recently. Many were not killed immediately and
they may have had time to digest any food in their stomachs.
Determinations of the prey down to species were possible in relatively
few instances; usually only the family or the order could be determined.
Those who have attempted food habits studies of insectivorous small
vertebrates will appreciate the obstacles encountered. The invertebrates
available to the skinks in the area of the study included many thousands
of species. A large number of these species, perhaps the majority,
belong to groups still not thoroughly studied, so that their taxonomy is
in a state of confusion. Ordinarily the prey is crushed in the jaws and
battered on the ground before ingestion; diagnostic structures are often
broken or lost, making identification far more difficult. Prey animals
taken are often in immature or larval stages which lack the
distinguishing features presented by adults. Even the combined efforts
of a team of specialists on each of the prey groups involved probably
would not have sufficed to obtain generic and specific identification of
every item found. In the present study, however, all determinations were
made by the writer, with the aid of the small reference collection at
the University of Kansas Natural History Reservation.
The 80 specimens used for stomach contents analysis nearly all came from
localities off the Reservation, but all within a ten-mile radius
thereof. A dozen localities were represented by these specimens, and
within each locality specimens were taken in somewhat different
situations. Therefore the stomach contents analyzed represents a wide
range of ecological conditions, including many different microhabitats.
All the stomach contents were collected in late April, May, and
June--within the first half of the skinks' active season. Trends might
be expected to differ in late summer and fall.