ground on a locust trunk. As I approached the skink continued upward to
a height of approximately 15 feet above the ground where it disappeared
around the trunk and could not be relocated.
July 7, 1950. A nearly grown juvenile ran to an elm sapling four inches
in diameter, and climbed up out of reach. When the skink reached the
main crotch, it turned facing downward alertly. By reaching up with a
long stick and poking it on the hindquarters, I succeeded several times
in chasing it part way down the trunk, but each time it ran back up to
the crotch and returned to the same position.
July 26, 1950. A hatchling uncovered beneath a flat rock ran to a nearby
oak tree about four inches in diameter and climbed to a height of five
feet before it was caught. An adult female seen foraging in the open ran
to a dead shrub and climbed one of the stems, inclined at an angle of
about 45 deg.. Ascending this stem she was unable to get more than three
feet above the ground, and was easily captured. Another adult female
seen foraging in the open ran to an oak about three inches in diameter,
climbed rapidly to a height a little more than a foot above the ground,
and concealed herself under the stem of a poison ivy vine twined about
the tree trunk.
July 27, 1951. A female brooding her eggs dashed out of the nest when
the flat rock covering it was lifted, ran 15 feet to a hickory sapling
and climbed it.
May 1, 1952. An adult male found beneath a rock ran to a small tree ten
feet away, climbed up on the opposite side, and stopped about a foot
above the ground. My first attempt to seize it failed and it ran around
the trunk and stopped at a height of four feet. The next try was
likewise unsuccessful, and the skink dropped to the ground and burrowed
into leaf litter.
May 15, 1952. An adult male startled as it basked in a patch of sunlight
in thick woods, dashed 25 feet without stopping, to an osage orange tree
and disappeared behind the base of the trunk. Moving to the far side of
the tree I located the skink clinging to the trunk two feet above the
ground. My attempt to catch it failed and it spiralled up the trunk to a
height of ten feet. When I poked at it with a stick, it crouched close
to the trunk allowing the stick almost to touch it, then it spiralled
down the trunk and could not be relocated.
June 23, 1952. When I struck the trunk of a partly dead ailanthus tree
with a brush knife to determine whether it was hollow, a juvenile darted
out of a cavity five feet above the ground, ran farther up the trunk,
and disappeared into another small hole. An adult male was seen running
across the vertical wall of a building, clinging to the rough asphalt
siding. When it was alarmed it ran to a crevice and hid.
A more unusual escape-reaction was observed on May 25, 1952, at
Tonganoxie State Lake, by Sydney Anderson, who recorded that a skink,
alarmed by him at the edge of the water dived and hid among submerged
rocks. Similarly, Boyer and Heinze (1934:194) record of this species, in
Jefferson County, Missouri: "When pursued they do not hesitate to take
to the water and are very agile swimmers over short distances at least."
Parker (1948:25) wrote that in western Tennessee _fasciatus_ sometimes
showed a preference for habitat in the vicinity of water, and, if other
concealment was not available, it would usually take refuge in the
water.
NATURAL ENEMIES
Little is known concerning the kinds of predators that destroy
five-lined skinks, or their importance in its ecology. In studies of the
food habits of various predatory birds and mammals, workers often have
been interested chiefly in items of direct economic bearing, and have
tended to lump as "lizard" or "reptile" material that might have
included _Eumeces fasciatus_. I have been able to find only a few
specific references to predation on it. Nevertheless many kinds of
predators probably utilize it as food, at least occasionally. Owls
probably seldom have opportunity to prey on these skinks, which are not
known to be active after dark. Nestling broad-winged hawks observed in
1954 were found to have eaten an adult and a subadult five-lined skink
on June 13 and June 23. The Cooper's hawk and red-shouldered hawk also
are probable predators as both are known to feed upon small reptiles.
Mammalian predators which might be expected to take skinks occasionally
include the red fox, gray fox, bobcat, mink, weasels, skunks, opossum,
armadillo, moles, and shrews. Snakes, especially those of the genera
_Elaphe_, _Lampropeltis_, _Cemophora_, _Micrurus_ and _Ancistrodon_, may
include some of the chief predators on the skink. Certain larger lizards
also may prey upon it.
Of these several potential predators, only the opossum, armadillo, and
snakes (_Elaphe obsoleta_, _E. guttata_, _Lampropeltis triangulum_, _L.
calligaster_, _L. getulus_, and _Ancistrodon contortrix_), Sonoran skink
and the greater five-lined skink (in confinement) have actually been
recorded as preying on _Eumeces fasciatus_ but circumstantial evidence
has been obtained for the mole (_Scalopus aquaticus_) and short-tailed
shrew (_Blarina brevicauda_). The short-tailed shrew may be one of the
major predators on the skink. This shrew prefers the same habitats and
occurs throughout the skink's extensive range. Like the skink, it is a
characteristic inhabitant of the hardwood forests of the eastern United
States, but its range extends farther north and west. A high proportion
of the skinks examined had scars, usually on the sides or dorsal surface
of the body, or of the tail near its base--wounds which must have been
made by a small, sharp-toothed animal. For example, in May 1951,
eighteen per cent of 155 skinks captured on the study areas had such
scars. The incidence seemed to vary according to age and possibly sex;
the scars were present in 22.9 per cent of the adult males, 25.5 per
cent of the adult females, and only 9.8 per cent of the yearlings (these
three groups being represented by approximately equal numbers in the
sample). As the scars are more or less permanent, adults could be
expected to show a much higher incidence than young. Females, being
inclined to stay in their nest burrows and defend them against small
predators, may receive more wounds than the males, which are quicker to
escape. None of the invertebrates present on the study area is
sufficiently large or powerful to inflict such wounds, and none of the
birds, reptiles, or amphibians has a dentition capable of producing
them. The wood mouse (_Peromyscus leucopus_) is the most abundant small
mammal in the skink's habitat; other rodents present in relatively small
numbers include the prairie vole (_Microtus ochrogaster_), harvest mouse
(_Reithrodontomys megalotis_) and pine vole (_Microtus pinetorum_). Both
voles and harvest mice have been known to kill skinks caught in the same
traps with them, but individuals experimentally placed with skinks in
captivity have failed to molest them and it seems likely that the
attacks in traps were motivated by extreme hunger or self defense. The
irregular scars from lacerated wounds characteristic of the skinks bear
little similarity to rodent bites, in which the long, sharp-edge
incisors make slit-like punctures. Other small mammals abundant in the
places where skinks were studied were the insectivores: the common mole,
short-tailed shrew, and least shrew (_Cryptotis parva_).
On one occasion when a large five-lined skink was put in a terrarium
with a recently captured short-tailed shrew, each displayed strong
aversion for the other. The skink crouched, attempting to conceal itself
in the end of the terrarium farthest from the shrew, and resisted
efforts to drive it toward the shrew. In exploring the terrarium the
shrew several times sensed the skink's presence, and then scampered away
in frantic haste. The skink also rushed away several times when the
shrew came close enough to disturb it. Three days later, when the shrew
had become accustomed to the terrarium, the test was repeated, with
different results. The shrew, having finished the food left for it, was
noticed moving about the terrarium, sniffing and testing objects with
its tactile snout, obviously hungry and searching for more food. The
skink was then dropped near it. In a few seconds the shrew sensed the
skink's presence and pounced upon it, and bit hard on its back. The
skink reacted with a violent flexure of its body which caused the shrew
to release it instantly, and both rushed away in opposite directions.
After a few seconds the shrew located the skink again, and moved up to
it with little hesitation but with nervous alert sniffing, and delivered
another quick bite after which the two separated as before, the skink
showing signs of injury. Soon the shrew attacked a third time, and bit
the skink's tail severing it near the base. As the skink rushed away,
the detached tail performed lively squirming movements, but the shrew
seized it, held it down, and began to eat the exposed flesh on the
broken end as the tail writhed. After rapid nibbling it would drop the
tail, and leaving it temporarily would explore the terrarium. Several
times on these trips it encountered the skink and renewed its attack. As
death of the skink seemed imminent, it was then removed, and it survived
with no apparent ill effects. The wounds inflicted by the shrew bore
close resemblance to those noticed on skinks in the wild. It seemed
almost certain that _Blarina_ had inflicted most of these wounds or all
of them. On subsequent occasions several other captive shrews that were
tested, quickly killed and ate skinks that were introduced into their
containers. The least shrew, _Cryptotis_, likewise occurred in all
situations where skinks were taken, and in some localities was more
abundant than the larger _Blarina_. Bites inflicted by these two kinds
of shrews might be indistinguishable, but because of its larger size,
_Blarina_ would seem by far the more formidable enemy.
Reynolds (1945:367) found _E. fasciatus_ to be the most frequent reptile
in a collection of opossum scats from Missouri, with two occurrences in
100 fall scats and ten occurrences in 100 spring scats. Sandidge
(1953:98 and 101) recorded one of these skinks among numerous other
items identified from stomach contents of sixty-six opossums. Probably
the opossum is a frequent predator on this skink. Although no specific
instances were obtained on the area of the study, flat rocks a few
inches in diameter frequently have been found flipped over, larger ones
and those solidly anchored in the ground have been found partly
undermined by opossums scratching away the loose dirt at their edges.
The rocks found disturbed by opossums were typical of those used as
shelter by the skink. On many occasions wire funnel traps set for skinks
and other reptiles along hilltop rock ledges were found to have been
disturbed, either shifted in position or with their rock shelters
removed, or rolled downhill or broken open. Similarly, heavy flat rocks
used to cover pitfalls, to protect the small animals falling into them
from predators, often were found to have been shifted somewhat, or
completely removed. When such raids became frequent and troublesome,
steel traps were set beside the reptile traps to discourage the raiders
or catch them and determine their identity. On several occasions
opossums were caught and somewhat less frequently, spotted skunks
(_Spilogale interrupta_). These skunks probably prey regularly on
lizards including the five-lined skink. However no definite records were
obtained. Crabb (1941:356-358) in his food habits study of the spotted
skunk in southeastern Iowa, did not record this or any other species of
reptile among the items identified in 834 scats. On the Reservation both
opossums and skunks were, in many instances, attracted to the reptile
traps by the insects and other arthropods in them, rather than by
lizards. The striped skunk (_Mephitis mephitis_) is another of the
predators which probably feeds upon the five-lined skink occasionally on
this area.
In the contents of 103 armadillo stomachs collected in west-central
Louisiana, in 1947 and 1948 I found the broken tail of one _Eumeces
fasciatus_. The lizard itself evidently had escaped (Fitch, 1949a:88).
Many clutches of lizard eggs were found in the contents of the armadillo
stomachs and some of these probably were eggs of _Eumeces_, which are
similar to those of other small lizards in the same region (_Anolis
carolinensis_, _Sceloporus undulatus_) in size, shape, and color.
Among 217 identified prey items from stomachs and scats of Sonoran
skinks (_Eumeces obsoletus_) from northeastern Kansas were remains of
three hatchling five-lined skinks. Taylor (1953b:212) recorded that a
_Eumeces laticeps_ shipped from Arkansas to Kansas ate an _E. fasciatus_
that was with it in the container. Several authors have recorded
predation on _Eumeces fasciatus_ by snakes of various kinds in
captivity. Conant (1951:211) recorded that one was eaten by a blacksnake
(_Coluber constrictor_) placed in the collecting sack with it. Anderson
(1942:211 and 216) recorded that a king snake (_Lampropeltis getulus
holbrooki_) and a young copperhead (_Ancistrodon contortrix_) each fed
upon them. Hurter (1911:184) recorded that a milk snake, _Lampropeltis
triangulum syspila_, placed in a bucket with a _Eumeces fasciatus_ was
found swallowing it a short time later and its tail had been broken off.
Ruthven (1911:268) mentioned that stomachs of milk snakes, _L. t.
triangulum_, collected in Michigan contained remains of five-lined
skinks. Ditmars (1907:352) wrote that stomachs of several _L. t.
elapsoides_ contained _Eumeces_, and Wright and Bishop (1915:167) wrote
of the same kind of king snake in the Okefinokee Swamp region: "It
feeds on ground lizards, skinks, swifts, and other snakes and lizards."
Mr. Richard B. Loomis is of the opinion that the five-lined skink is one
of the chief food sources for the milk snake (_L. t. syspila_). Having
kept many of these snakes in captivity and experimentally offered them
different types of prey, he found that individuals inclined to feed
would avidly seize and eat skinks and young mice, but other proffered
prey, small adult rodents, snakes, or lizards other than _Eumeces_ were
either rejected or were taken with some hesitation. These milk snakes
have habitat preferences similar to the skink, which would seem to be
one of the most available food sources. Loomis recorded in his field
notes that a juvenal blotched king snake (_L. calligaster_) 310 mm. in
total length, taken on April 8, 1950, seven miles southwest of Tulsa,
Oklahoma, had eaten a large adult _E. fasciatus_. Another juvenal
blotched king snake that he found under a flat rock near Sunflower,
Johnson County, Kansas, regurgitated an adult five-lined skink. Loomis
also recorded a juvenal rat snake (_Elaphe guttata emoryi_) and a
juvenal pilot black snake (_E. obsoleta_) each feeding on individuals of
_Eumeces fasciatus_ in captivity. Uhler, Cottam and Clarke (1939:622) in
a study of the contents of the alimentary tracts of 893 snakes of 18
species, from the George Washington National Forest, Virginia, found
among the prey items only one skink (species undetermined but most
probably _E. fasciatus_). It had been eaten by one of the two corn
snakes (_Elaphe guttata_) that were examined in the study.
On June 11, 1950, in Skink Woods, a young copperhead 335 mm. in
snout-vent length and weighing 27.6 grams, had a gravid female skink in
its stomach. Another young copperhead (335 mm., 36.1 grams) trapped near
Rat Woods on August 28, 1953, had in its stomach a bob-tailed adult
five-lined skink. Many copperheads collected on the Reservation were
kept in captivity for short periods, and from them a total of 44 scats
were obtained, each scat containing the remains of one or more prey
animals eaten in the wild. Of this total, five scats contained remains
of _Eumeces fasciatus_, which was one of the more frequent items,
although small mammals collectively made up the bulk of the scat
contents.
PARASITES
Skinks, like many other lizards, are likely to be infested with
parasites. Little attention was devoted to the endoparasites in the
present study, but they were noted from time to time. On several
occasions small nematodes and flukes were seen in feces voided by
lizards which were handled. Small white cysts were seen in the body
cavities of several that were dissected.
Harwood (1932:65) examined for endoparasites nine _E. fasciatus_ along
with many other reptiles and amphibians collected near Houston, Texas.
Most of them were infested and five kinds of helminths were identified.
Two of the skinks were infested with _Oswaldocruzia pipiens_, a spirurid
nematode that was also present in various other lizards, snakes, toads
and frogs from the same region; four had _Comocercoides dukae_, an
oxyurid nematode also present in various lizards, snakes, turtles, and
frogs; one had in its intestine _Oochoristica eumecis_, named as a new
species by Harwood, and found only in _Eumeces_; one contained
_Cysticercus_ sp. in its body cavity, present in great abundance as
white globular structures .6 mm. in diameter (Harwood states that
possibly these were larvae of _Oochoristica_). One skink contained
_Mesocoelium americanum_, a dicrocoelid trematode which was found also
in the brown skink (_Scincella laterale_) and DeKay's snake (_Storeria
dekayi_).
The ectoparasites of these skinks consist mainly of chiggers. Wharton
(1952:135) lists three species; _Trombicula alfreddugesi_, _T.
splendens_, and _T. gurneyi_. The first species is the common pest
chigger of humans and domestic animals in the United States, and south
through tropical America. Wharton lists 136 known hosts which are fairly
evenly divided among mammals, birds and reptiles; he lists four kinds of
frogs and toads. _Trombicula splendens_ is a similar and closely related
species which has been recorded from thirty-eight vertebrate hosts
including mammals, birds, reptiles, and a tree-toad. _Trombicula
gurneyi_ belongs to a separate subgenus and it was originally recorded
from _Eumeces fasciatus_ which seems to be one of the principal hosts.
Two of these mites, _T. alfreddugesi_ and _T. gurneyi_, were on skinks
collected on the Reservation, and nearby areas. A four year study of the
chiggers in this general region by Loomis (MS), Wolfenbarger (1953) and
Kardos (MS) has clarified the ecological relationships of the several
kinds of chiggers present, including their local distribution with
respect to vegetation, soil type, moisture and temperature, host
preferences, and seasonal occurrence. At the quarry, Rat Woods and the
pond rock pile, the chigger population consisted chiefly of _T.
alfreddugesi_, while at Skink Woods _T. gurneyi_ was also abundant. In
some local situations where they are among the most abundant of
vertebrates the skinks probably are important as hosts of _T. gurneyi_.
An individual skink may have dozens of chiggers on it at one time but
usually there are fewer.
There are several favorable sites of attachment. The most favored site
is in the axilla. There the scales are minute and granular with exposed
areas of thin and tender skin, and the chiggers are well protected from
dessication and are not likely to be rubbed off as the skink moves
about. Other favorite sites of attachment are: about the insertion of
the hind limb, about the cloacal opening, on the eyelids and on the
toes. Only occasionally are chiggers found attached on the dorsal
surface. When attached in protected spots in the tender skin of the
axilla or groin, they are often in dense clusters of a dozen or more.
Damage to the skin resulting from the attachment of the first chiggers
renders conditions more favorable for the attachment of others. At Rat
Ledge and at the quarry, many of the larger Sonoran skinks (_Eumeces
obsoletus_) were captured, and individuals were far more heavily
infested than were _E. fasciatus_ from the same places. A single Sonoran
skink might be found to have hundreds of chiggers, widely distributed
over its body with concentrations at the axillae, groins, lateral neck
region, and any injured spots where the protective armor of scales was
broken. The reasons for the greater susceptibility of _E. obsoletus_ are
not entirely clear. It is a larger, less active species with coarser
scalation, and is more subterranean in its habits.
The chiggers that attach to skinks seem to occasion but little
discomfort. There is no local swelling and inflammation such as occurs
in humans. The infestations observed in five-lined skinks were not
sufficiently severe to cause debilitation or any noticeable symptoms.
There is, however, a possibility that chiggers are vectors of
microorganisms causing diseases in reptiles, just as they are for
certain mammals (including humans) in some parts of the world.
Bishopp and Trembley (1935:42) record a single kind of tick, _Ixodes
ricinus scapularis_ Say, the black-legged tick, as parasitic in its
immature stages on _Eumeces fasciatus_. This tick, however, has been
recorded principally from mammals, of which many kinds serve as hosts
for its larval, nymphal, and adult stages.
Population
COMPOSITION
Population structure obviously differs from place to place and from time
to time. Because of the differences in secretiveness and elusiveness
between young and adults and between males and females, true sex ratios
and age ratios are obscured. In the period of weeks between the
emergence from hibernation and the onset of the breeding season, these
skinks tend to be less secretive than at other times, and secondary
sexual and age differences in behavior are minimized. A sample at this
season should be more representative of the true population composition
than samples taken at other times of year. In a sample of 308 skinks
available for the month of April, including the collections made on the
Reservation and on nearby areas, in 1949, 1950, 1951, and 1952, 36.7 per
cent were adult males, 28.3 per cent were adult females, and 35.0 per
cent were young. That these figures cannot, however, be accepted as an
accurate indication of the population composition is shown by the data
from the areas where intensive population studies were made. Data are
most complete from Skink Woods. For 292 adults taken there over a four
year period, the sex ratio was 100:122.6. On this area after the first
year of study a substantial proportion of the individuals recorded were
repeaters from one year to the next, and in some cases for three or even
four successive years. Many could be definitely assigned to a known age
group. By analogy the majority of others could be tentatively assigned
with some assurance on the basis of measurements, and relatively few
were of indeterminate status. By assigning each of these indeterminate
individuals to one or another age group, on the basis of greatest
probability, the approximate composition of the population could be
determined. Of 611 adults, 55 per cent were "two-year olds" (in the
season between their second and third hibernations, which was their
first breeding season). The percentage was not significantly different
in the two sexes.