Life History and Ecology of the Five-lined Skink, Eumeces fasciatus Part 11

The scatological material was even less satisfactory than the stomach material in providing determinable food items. The scats of these skinks are, roughly, 10 to 20 mm. long and two to four mm. in diameter, usually cylindrical and almost straight, and capped at one end with a white chalky deposit of uric acid. Superficially they have some resemblance to bird droppings, but are different in texture. The uric acid deposit is loose and crumbly, and much less compact than that with bird feces, and the food residue is much less completely disintegrated than is similar material in feces of birds. Common small snakes which might produce feces of similar size, include the ring-necked snake (_Diadophis punctatus_), the worm snake (_Carphophis amoenus_), and DeKay's snake (_Storeria dekayi_), but their feces have a much higher moisture content, lack the definite shape of the skink scats, and ordinarily do not contain readily recognizable residue of the prey. The six other species of lizards on the Reservation, the collared lizard (_Crotaphytus collaris_), brown skink (_Scincella laterale_), prairie skink (_Eumeces septentrionalis_), Sonoran skink (_E. obsoletus_), six-lined racerunner (_Cnemidophorus s.e.xlineatus_) and gla.s.s "snake" (_Ophisaurus attenuatus_) might produce scats indistinguishable from those of the five-lined skink. However, none of these lizards except the relatively rare and secretive brown skink, occurred in either of the two situations where most of the scats were collected and it is highly improbable that the scat collection included any material from species other than the five-lined skink.

The scats consist mainly of chitinous fragments of arthropod prey.

Usually the prey fragments are so well comminuted, mixed, and scattered that reconstruction is difficult. Degree of disintegration differs greatly, depending not only on the type of prey eaten, but probably also on the condition and temperature of the lizard, and the amount of other food in its digestive tract. Arthropods which have recently undergone ecdysis and have the exoskeleton still thin and soft are no doubt digested much more completely than those that have more heavily sclerotized parts. In spiders the chelicerae are more resistant to digestion than are other parts of the exoskeleton, and frequently appear, intact or nearly so, in the scat contents. The fangs being even more resistant, were sometimes found separately when no other cheliceral parts were recognizably preserved. Frequently large fragments of the carapace, with some of the eyes or all of them, were found. Spider abdomens sometimes were distinguishable, but were collapsed and compressed. Spider legs conspicuous in most of the scats, were so broken, tangled, and distorted that they were of little diagnostic value. In harvestmen, dorsal s.h.i.+elds were nearly always fairly intact; but only small fragments of the elongate slender legs were found and they were mostly broken off when the attacking skinks battered the phalangid against the ground before swallowing it. The h.o.r.n.y outer wings of crickets, roaches, and beetles usually were in recognizable though fragmentary condition. Occasional heads of insects often were found fairly intact. Insect legs were sometimes intact, sometimes broken into sections or crushed and fragmented. The thorax was usually represented by scattered fragments of chitin, and the abdomen by the separate chitin bands of each body segment.

Sh.e.l.ls of snails were sometimes found nearly intact in the scats, although showing the effect of the digestive juices in their extreme brittleness. In other instances all that remained of the sh.e.l.l was the inner columella, and small scattered fragments.

Certain of the items eaten were probably so thoroughly digested as to leave either no hard parts at all, or minute and nondescript parts that were not recognized. The common small slug _Deroceras laeve_, for instance, would seem to be just as suitable and available for food as the various kinds of snails, but it was not recorded in either stomachs or scats. Having no hard parts except the vestigial internal sh.e.l.l, it probably would not be recognized in scats, even though it had been eaten. Various insect larvae, having thin outer cuticles and virtually no hard sclerotized structures except in the head, likewise probably would leave no recognizable parts. Molted skin of the skinks themselves seemed to be little altered by the digestive processes.

Table 16. Frequency of Occurrence by Months of Various Types of Prey in a Collection of 371 Scats of Eumeces fasciatus.

=========================+========+======+======+======+=======+======= May (and June July Aug. Sept. Total April) -------------------------+--------+------+------+------+-------+------- Spider unspecified 32 32 16 100 10 190 salticid 10 18 5 31 7 71 lycosid 7 1 3 18 4 33 Harvestman (phalangid) .... 7 1 16 2 26 Orthopteran unspecified .... 4 .... 14 .... 18 cricket (ceuthophilid) .... 6 11 31 2 50 cricket (gryllid) 2 1 .... 16 1 20 grouse locust 3 2 .... 17 2 24 gra.s.shopper .... .... .... 6 .... 6 roach 1 2 .... 2 .... 5 Beetle 4 13 1 11 2 31 Ant .... .... 1 .... .... 1 Wasp 1 .... .... 1 .... 2 Caterpillar 1 .... .... 1 1 3 Other insects 3 8 6 45 5 67 Five-lined skink slough 2 1 3 12 1 19 hatchling .... .... .... 1 1 2 Snail unspecified 3 6 6 8 6 29 _Gastrocopta_ .... 2 .... 8 1 11 _Retinella_ 1 1 .... 6 .... 8 +--------+------+------+------+-------+------- Total 70 104 53 344 45 616 -------------------------+--------+------+------+------+-------+-------

The collection of 371 skink scats originated mainly from two places on the Reservation nearly three-quarters of a mile apart, the pond rock pile and an old wooden bridge across a ravine. On the weathered planks of the bridge, the scats were conspicuous and could be easily gathered in quant.i.ty. At the pond rock pile, where skinks were especially abundant and were intensively studied, their scats were frequently noticed on the large rocks where they hunted and basked. A third smaller collection of scats was made in the vicinity of the laboratory buildings and adjacent rock walk frequented by a few skinks. A small number of additional scats were collected elsewhere on the Reservation, but ordinarily the scats were so inconspicuous in the woodland situations where skinks occurred under typical habitat conditions, that few were found. The rock pile, bridge, and vicinity of buildings are not typical of the species' habitat and might offer somewhat different choices of prey items.

The 30 scat collections were made in 1951 and 1952. Seasonally, the sample of scats overlapped but little the sample of stomach contents, and was concentrated in the latter half of the growing season. The distribution by months was as follows: April-2; May-38; June-60; July-29; August-213; September-26. Most of the scats probably were deposited within a few days of the time they were collected, because scats disintegrate and disappear rapidly in the field where they are exposed to rain, wind and dung-feeding insects.

No clearly defined seasonal trends are revealed in Table 16 but the monthly samples, except that for August, are scarcely adequate for this purpose. Approximately equal numbers of scats were collected at the two main stations, the pond rock pile and the bridge, but some kinds of items were unequally represented in the two samples.

Table 17. Comparison of Frequency of Occurrence of Various Food Items in Two Different Small Areas, Based on Scat a.n.a.lysis.

======================+=================+=================+================== Total from Percentage of Percentage of both collecting total in bridge total in pond stations sample rock pile sample ----------------------+-----------------+-----------------+------------------ Spiders (all) 292 63.3 36.7 salticids 67 79.2 20.8 _Phidippus audax_ 16 100.0 _Phidippus sp_ 3 100.0 lycosids 33 36.3 63.7 harvestmen 28 57.1 42.9 ceuthophilids 39 30.8 69.2 grouse locusts 25 92.0 8.0 crickets 26 42.3 57.7 snail 34 61.9 38.1 _Gastrocopta_ 11 91.0 9.0 _Retinella_ 6 50.0 50.0 ----------------------+-----------------+-----------------+------------------

Spiders, harvestmen, and snails were well represented in both samples.

In the bridge sample, salticids (especially _Phidippus audax_), grouse locusts, and the snail _Gastrocopta_ were more numerous. In the rock pile sample lycosids, and especially ceuthophilid crickets were more abundant. The ceuthophilids were notably numerous among the rocks, and many of them were caught in the wire funnel traps placed there for skinks.

Little is known concerning the quant.i.tative food requirement of any kind of lizard. Five-lined skinks fast for at least half the year during the period of dormancy, from September to April. When they emerge from dormancy in spring most of them are plump and appear to have lost little weight in the course of their long fast. In the season of activity, obviously the quant.i.ty of food consumed fluctuates according to temperature and activity of the lizard. Most of the prey taken falls within a fairly narrow size range. The prey ordinarily is swallowed entire or nearly so. This imposes a definite upper size limit. The skink of course lacks the ophidian capacity to ingest relatively enormous objects. The mental symphysis and pectoral girdle would prevent ingestion of an object much larger than the skink's body diameter, but soft-bodied and flexible arthropods of body diameter approximately equal to that of the skink may be ingested. Typical food items are of such size that from one to three of them fill the stomach to capacity. On one occasion, in an attempt to feed a brood of young recently hatched in the laboratory, I dropped into their jar a ma.s.s of newly hatched house spiders (_Theridion tepidariorum_). As these minute spiders swarmed over and around the skinks, the lizards gave little heed to them except occasionally to jerk or scratch in irritation. One skink, however, was seen to snap up a spider which ran near its snout. The adult female _Theridion_ from the same web was then introduced into the skinks' jar, although it seemed too large prey for these small lizards, as its abdomen was fully as large as their body diameter. When it ran, the hatchling skinks immediately became alert and several chased it biting at it in frantic excitement. They had difficulty in grasping its smooth rounded surface, but eventually one did catch it and eat it. Full-grown mealworms averaging 26 mm. in length, and approximately .11 grams, are somewhat smaller than the usual prey of adults. In captivity hungry adult skinks took from one to nine such mealworms at a meal. However, they could not be induced to feed daily over periods of weeks, even when kept at high temperatures. Over a period of 64 days an adult male kept at approximately 80 F. in the daytime and 10 to 15 degrees lower at night, ate a total of 30 mealworms, which, in the aggregate, weighed approximately 42 per cent of his body weight. In 35 days under the same conditions an adult female ate 24 mealworms, approximately 32 per cent of her body weight.

[Ill.u.s.tration: FIG. 26. Map of University of Kansas Natural History Reservation showing locations of the four study areas (shaded) where most data on five-lined skinks were obtained.]

Predation and Parasitism

ESCAPE REACTIONS

Like other members of the family Scincidae, _Eumeces fasciatus_ tends to be secretive in its habits and it depends on concealment rather than speed, aggressive behavior, or noxious qualities to escape its enemies.

As compared with lizards in general, or with other members of the genus _Eumeces_, five-lined skinks are relatively unspecialized in their behavior, and retain a good deal of versatility. While primarily terrestrial, they are able to burrow and climb. Their reactions toward prey and natural enemies vary greatly according to circ.u.mstances.

They are less secretive than many other kinds of skinks. Nevertheless the numbers active on the ground surface at any one time, even under the most favorable weather conditions, probably are only a fraction of the total population. For instance, in two or three hours of intensive search in Skink Woods, in which almost every square yard of the area was inspected, a dozen skinks const.i.tuted an unusually good catch. Seldom were as many as 20 seen--and most of these only when uncovered in their hiding places. At the pond rock pile, often half a dozen or even more could be seen simultaneously or within the course of a few minutes, as they basked or darted about over the rock surface. These, however, represented only a small part of the number known to occur in the rock pile, which could be observed in its entirety from one spot. At other times, especially in late summer and early fall, even when weather seemed favorable, cursory search of each of the study areas failed to reveal a single individual. Presumably at such times the majority of individuals of the dense population were sheltered deep underground in relatively inaccessible hiding places. Others which escaped attention may have been climbing on tree trunks or logs, or may have been foraging on the ground but close to hiding places into which they darted undetected. The habit of "freezing" in response to a potential danger is commonly noticed in these skinks, and usually it is effective in concealing them.

Having elongate bodies and short limbs, five-lined skinks are not especially swift of foot, but the jerkiness of their movements provides compensatory elusiveness. One sufficiently warm to be fully active is nervous in its actions. Even when resting or basking it is likely to s.h.i.+ft its position frequently, fidgeting, blinking, and panting, obviously on the alert for any sign of danger. In moving about, it usually progresses only a few steps at a time, with frequent pauses sometimes only a fraction of a second in duration. These numerous stops allow the animal to examine the terrain immediately ahead of it, and perhaps avoid blundering within reach of a lurking enemy.

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 flas.h.i.+ng 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 las.h.i.+ng 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.

In hatchlings the mortality rate is high. Tails are broken frequently in those that survive, suggesting that the tail may be useful in diverting enemies from the lizard itself. Among 121 young of the smallest sizes, (snout-vent lengths in the range of 23 to 29 mm.) 7.4 percent already had broken tails (not including, of course, those in which the tails were broken while the skinks were being captured). In slightly larger young, those in the 30-34 mm. range, perhaps averaging one month old, nearly one-fourth had lost their original tails. In those in the 35-55 mm. size cla.s.s, mostly one to three months old, about half have already lost parts of their original tails. In those that are in the size group 65-69 mm. normally attained at an age of a year, approximately three-fourths have regenerated tails, and in adults the proportion with unbroken tails is even smaller--down to 16.5 percent in females of more than 75 mm. snout-vent length. In adults the incidence of broken and regenerated tails is slightly higher in females than in males. Defense of nests and sluggishness in the females during the time that they are excavating the nest burrows and guarding their eggs may result in their tails being broken more frequently.

Tree-climbing is a common means of escape and it is curious that many of those who have described the habits of _E. fasciatus_ have either failed to note it at all or have minimized arboreal habits. Taylor (1936:59) cited two instances of tree-climbing but stated: "Only rarely is this form seen in trees, at least in the western part of its range." Conant (1951:30) stated: "They seldom climb trees, contrary to the habit of _laticeps_ and _inexpectatus_." Hudson (1942:42) mentioned seeing an adult that escaped by climbing the side of a hollow tree in southeastern Nebraska.

In the present study, tree-climbing as a means of escape was observed frequently, probably more than two hundred times in all. It was characteristic of both s.e.xes and all ages, and was one of the commonest responses to danger. In summer when skinks were fully active, they usually moved too rapidly to be caught by hand either in the open or where they were uncovered when I turned over rocks or other shelter. To obtain specimens in any numbers at such times, an understanding was essential of the somewhat stereotyped behavior pattern involved in their escape by tree-climbing. A skink that was alarmed in the course of its foraging or basking on the ground litter was likely to run directly to the nearest tree trunk, often a distance of several or many yards, and start up it, instantly disappearing to the far side of it. The trees climbed were usually small, two to eight inches in trunk diameter; however, in the second growth forest where the study was made, large mature trees were relatively scarce. Having started up the tree trunk and concealed itself on the side opposite from its pursuer, the skink usually stopped one to five feet from the ground and waited quietly for the danger to pa.s.s. A vine of Virginia creeper, poison ivy, grape or moonseed, or a shrub such as gooseberry, providing screening foliage at the base of the tree trunk, furnished the type of sheltered situation that the skink was most likely to choose as a stopping place. The most effective technique for catching the lizard was to move slowly around the tree trunk at a distance of at least 20 or 30 feet and look for the lizard clinging to it. Having located the lizard, the collector might take careful note of its position, then return to the opposite side of the tree and approach, unseen, to close range to make a sudden grab around the trunk. This ruse often succeeded; more frequently it failed, because of the lizard's adroitness in dodging, or failure of the collector to gauge its position accurately, or a slight s.h.i.+fting of its position between the time it was seen and the time when an attempt was made to catch it. The response of the lizard to the unsuccessful attempt to seize it depended on whether or not it was touched, and in which direction it was driven. It might drop to the ground and burrow into leaf litter or dash away to other shelter, or it might stay on the tree trunk and spiral rapidly upward out of reach. Because of the squirrel-like tendency to keep the tree trunk between it and the pursuer, the skink usually could be relocated only after some maneuvering. Having climbed the tree trunk to the bases of the main branches, the skink usually showed little inclination to move out along them but tended to hide in the crotches or to spiral back down the trunk. Often a long stick or pole was used effectively to drive a skink back down the trunk by touching or pus.h.i.+ng it on the upper side. A skink maneuvered to the lower part of the tree trunk was never loath to leave it in a dash for other shelter, which might be another tree trunk nearby. In moving downward or horizontally on a tree trunk or limb, a skink allows its heavy tail to bend downward from its own weight. The tail probably handicaps the lizard's climbing to some extent, and those with short regenerated tails have an advantage.

The following extracts from my field notes are selected as typical ill.u.s.trations of the climbing habit as a response to danger.

September 15, 1948. A skink darted across the trail in front of me, to a tree 18 inches in diameter and climbed to a height of five feet where it stopped. Each time that I moved to approach and examine it, the skink was disturbed, and darted jerkily higher up the trunk until it was well out of reach at a height of about ten feet.

May 2, 1949. Seeing an adult male skink lying in the open, I attempted to stalk it, but it became alarmed, ran to a s.h.a.gbark hickory about six inches in diameter, and soon had climbed to a height of 25 feet.

June 4, 1949. Juvenile, basking a few inches above ground on trunk of an elm ten inches in diameter, took alarm at my approach, and climbed rapidly out of reach, where it concealed itself in thick foliage.

June 22, 1949. Movement two feet above ground on an elm sapling attracted my attention; an adult male and a juvenal skink were clinging to the trunk only a few inches apart, and neither moved as I approached and examined them from a distance of less than three feet. The concealment afforded by numerous short twigs with thick foliage apparently caused them to feel secure.

September 21, 1949. A juvenile was noticed climbing eight feet above the 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. 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 circ.u.mstantial 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 s.e.x; 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 dent.i.tion 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 anch.o.r.ed 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 s.h.i.+fted 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 s.h.i.+fted 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 ident.i.ty. 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.