Fig. 8.Adult female skinks with ventral body walls removed to show reproductive organs. A. Condition in April shortly before the breeding season; the ovary (O) is still small and elongate, with the small ova forming a grapelike cluster; right ovary removed to expose the small bandlike oviduct (OD) beneath it. B. Condition in late May shortly before ovulation; the greatly enlarged ovaries are removed to expose the oviducts (OD) now enlarged and convoluted for reception of the ova. C. Same stage as B, with mature ova (O) filling most of the body cavity and concealing other internal organs, I—intestine; L—liver; approximately natural size.
Fig. 8.Adult female skinks with ventral body walls removed to show reproductive organs. A. Condition in April shortly before the breeding season; the ovary (O) is still small and elongate, with the small ova forming a grapelike cluster; right ovary removed to expose the small bandlike oviduct (OD) beneath it. B. Condition in late May shortly before ovulation; the greatly enlarged ovaries are removed to expose the oviducts (OD) now enlarged and convoluted for reception of the ova. C. Same stage as B, with mature ova (O) filling most of the body cavity and concealing other internal organs, I—intestine; L—liver; approximately natural size.
Sexual behavior is for the most part limited to a short period of weeks in spring. In an average year in the area of the study the first two weeks of May would include the peak and the greater partof the breeding season. The “courtship,” such as it is, and mating have been described by many observers. However none of the published accounts seems to include all the essential features in their usual sequence as observed in the present study. It has been brought out by the studies of Noble and Bradley (1933:94), Noble and Teale (1930:54) and Schmidt (1933:71-76) that the sexual behavior of lizards has phylogenetic significance. Certain basic patterns in mating behavior are characteristic of saurian families, other traits are characteristic of genera, while certain details may be characteristic of species, or perhaps even of subspecies.
In the breeding season the adult male directs the greater part of his activities to a search for females, and finds them by both sight and scent. Observations on searching males suggest that they trail females by scent to some extent, or at least detect their presence in the general vicinity by this means. Upon discovering a female, the male pursues her with vigor and determination unless the temperature is too low, or unless he is not at the height of breeding condition. The female makes no positive response but reacts to the male’s presence by fleeing, either frantically or perfunctorily, but if she is physiologically ready to breed the reaction is usually somewhat intermediate between these extremes. The first reaction of the male as he approaches the female is to touch her with his tongue, apparently receiving olfactory stimuli which are essential to the mating pattern. Rushing in pursuit of the female he then attempts to seize her in his jaws. Most often a preliminary grasp is secured on the female’s tail. The female may resist vigorously, wriggling and clawing, turning upon the male to bite or to threaten with her gaping jaws. At the first opportunity the male deftly shifts his grip from the female’s tail or hindquarters to a more anterior position, which may be as far forward as the forelimbs or may be as much as an inch behind them, a little to one side of the mid-dorsal line. The male secures his hold by pinching loose skin into a small fold. Having gained this position the male is more or less out of reach of the female’s jaws, and after a brief struggle both rest quietly except for their rapid breathing, usually for a minute or more, the ventral surface of the male resting on the female’s dorsal surface. The male suddenly thrusts his tail beneath that of the female. His hind leg then rests over the base of her tail and the right angle formed by the laterally projecting hind leg and the tail in each lizard aids to guide their hindquarters into position so that cloacal contact is established. Copulation then begins immediately. The male’s body may be bent in a semicircle, to one side of the female, or may be in an S-shaped loop, depending on whether or not the hemipenis employed is on the side opposite to that on which the female is grasped. Only one hemipenis is inserted, but occasionally the other may be everted also. As copulation begins the male’s hind leg, flexed over the female’s tail base quivers, but otherwise there is hardly any movement during approximately the first one-third of the copulatory period, and this phase may last for from one to three minutes. Then, abruptly, the male begins rhythmic, jerky flexions of the proximal portion of the tail, at the rate of approximately one per second. These tail movements are in a dorsoventral plane, and there is no perceptible movement of the body. Shortly after these movements cease, contact is broken usually at the initiative of the female, as she suddenly struggles to escape and is released either immediately or after a few seconds by the male. She then moves away, pressing her cloacal region against the ground. Her movements have become unhurried, with little or no attempt to avoid the male’s attention. The male usually follows, either close behind, or straddling the female’s tail or body. He may nip at her tail or body repeatedly, but without securing a grip. When the female pauses, he may come to rest with his chin or forequarters resting on her. Usually the association does not last more than a few minutes.
Fig. 1.Habitat ofEumeces fasciatusnear the center of the "Skink Woods" study area on the University of Kansas Natural History Reservation, a glade with loose rocks that were used as nesting sites and shelter by many five-lined skinks.
Fig. 1.Habitat ofEumeces fasciatusnear the center of the "Skink Woods" study area on the University of Kansas Natural History Reservation, a glade with loose rocks that were used as nesting sites and shelter by many five-lined skinks.
Fig. 2.A log on rocky slope in open woods with sparse undergrowth, fifty feet from center of glade shown inFig. 1. The trees are mostly oaks (Quercus Muehlenbergii). The decaying log in middle foreground is much frequented by the skinks as a shelter and source of insect food.
Fig. 2.A log on rocky slope in open woods with sparse undergrowth, fifty feet from center of glade shown inFig. 1. The trees are mostly oaks (Quercus Muehlenbergii). The decaying log in middle foreground is much frequented by the skinks as a shelter and source of insect food.
Fig. 1.Old adult male, year-old young and hatchling in July, showing differences in size and pattern.
Fig. 1.Old adult male, year-old young and hatchling in July, showing differences in size and pattern.
Fig. 2.Adult female skink in a natural nest, with her clutch of eggs late in incubation. The nest cavity is excavated in loose soil beneath a flat rock, which was raised momentarily to expose the nest to view.
Fig. 2.Adult female skink in a natural nest, with her clutch of eggs late in incubation. The nest cavity is excavated in loose soil beneath a flat rock, which was raised momentarily to expose the nest to view.
Fig. 3.The same female and nest, with eggs in process of hatching.
Fig. 3.The same female and nest, with eggs in process of hatching.
Noble and Bradley (1933:77) mention frequent homosexual matings between captive males. However, I observed no homosexual matings, either under natural conditions or in confinement. The pugnacious behavior of males that are in breeding condition ordinarily would prevent homosexual mating. Males in such weakened condition as to be unable to defend themselves effectively might evoke sexual attack, instead of the usual fighting response in other males. Although no actual experiments were performed in the present study in connection with the courtship and mating behavior, accounts of some workers seem misleading. My own observations indicate that the capacity for sex discrimination in this particular kind of lizard, and probably in others, has been underrated. For example, it has been stated that the male rushes with open mouth at the neck of any other skink that happens to be around, and he identifies it as a male if it fights back, or as a female if it does not. On the contrary my observations indicate that sex recognition occurs almost as soon as the male is aware of another skink’s presence. The red head of the breeding male is an excellent example of a social releaser in the sense that this term was used by Tinbergen (1948:8). Like the red belly of the breedingmale stickleback, it facilitates sex recognition and evokes hostile behavior on the part of other males. Courtship, mating, and fighting reactions however, seem to be evoked by the interaction of a complex of social releasers. Whereas males and females are strikingly different in appearance in the breeding season, visual sex recognition is complicated by ontogenetic changes. The body stripes characteristic of the female pattern, become dull or even disappear in some old females, which then approximate the typical male pattern. On the other hand newly matured males in their first breeding season retain distinct body stripes of the female pattern. Their sex is evidenced mainly by their reddish facial suffusion, which is not quite so extensively developed as it is in older individuals. Also, in these newly matured males the temporal region is not so swollen as it is in old males.
The male whose dormancy was terminated in early winter by bringing him into a warm room causing him to assume breeding coloration and to breed some four months earlier than those under natural conditions has already been mentioned. By the time the regular breeding season arrived, this male had long since undergone sexual regression and retained no trace of the red suffusion. In this condition, placed in a terrarium with a mixed group of breeding adults, his social status was of unusual interest. He exhibited no interest in the females and was less pugnacious toward other males than were the individuals in breeding condition. Although he seemed somewhat more nervous and timid, his hostile behavior was not entirely suppressed, as from time to time he moved up to other males and bit them viciously. His color pattern resembled those of certain old adult females in which the body stripes have been suppressed, but the breeding males evidenced no uncertainty as to his sex and were uniformly hostile. Their reactions were not noticeably different toward him than they were toward breeding males. The importance of an olfactory stimulus as a social releaser in sexual behavior of lizards has not been appreciated, although Noble and Mason (1933:10) did demonstrate its importance in the behavior of the female toward her eggs.
It is evident from published accounts, and from my own limited experience withfasciatusin parts of its range other than northeastern Kansas, that the phenology of the breeding cycle is subject to geographic variation, synchronizing with the somewhat different climatic conditions under which the species occurs. However, the difference is less than might be expected, in view of the species’ extensive range. As a result of the early spring, and the warmsummer climate in the southern states, dates of laying and hatching may be several weeks advanced. On April 12, 1952, Dr. Wilfred T. Neill showed me several liveE. fasciatus,collected a few days before along the Trinity River in southeastern Texas, which appeared to be at the height of breeding condition. In northeastern Kansas on that date, general emergence had not yet occurred, and it was not until about May 10 that the population attained the peak of breeding condition. On May 8, 1948, near Burr Ferry, Vernon Parish, Louisiana, I caught an adult female in her nest burrow, and she contained eggs ready to be laid. Data with which Mr. Robert Gordon kindly provided me for specimens from southern Louisiana and southeastern Texas, in the Tulane University collection, indicate gravid females on June 4, 1952, and June 17, 1948 (3), and females with their egg clutches on June 16, 1948, June 17, 1948, June 23, 1950; and hatching dates in captivity of July 19, 1949, July 19, 1950, July 25-26, 1949. These dates correspond well with those for specimens obtained in northeastern Kansas in the same years. In the northern part of the range, Ruthven (1911:264) recorded that in the Saginaw Bay region, females taken on June 19 had eggs nearly ready to be laid, and after July 2 clutches were found frequently; young of the year were first observed on July 31. A juvenal specimen in the University of Minnesota Natural History Museum, collected on August 11, 1938, at Dresser Junction, Wisconsin, is 301⁄2mm. in snout-vent length—approximately the size of juveniles in northeastern Kansas at the same season. Evans and Roecker (1951:6) record hatching as occurring in the first week of September at Arden, Ontario, indicating that at the northern edge of the range hatching may be delayed as much as two months. With such delayed hatching, but little time remains for the young to grow before they are forced into retirement for hibernation.
Territoriality in the usual sense is lacking in the five-lined skink, and could scarcely exist in an animal of its habits. To defend a definite area (territory) against intruders of its own species, the animal would have to detect such intruders promptly. The skink, however, is so secretive in habits that at any given time the individual is likely to be hiding and inactive, even when conditions are favorable for it to be in the open, and other individuals therefore can then wander onto its home range unopposed. Even when an individual is active, it lacks the ability to detect others, except within a radius which would encompass only a small fraction ofthe entire home range. The senses are inadequate to inform one lizard of the presence of another until the two are only a few yards, or even a few inches apart. Usually the lizard is on the ground, where even small objects obstruct its view, and vision is probably effective for only a few yards. Hearing is probably effective for about the same radius in detecting animals of approximately its own size. Scent is effective in detecting prey near at hand or on contact, but probably does not serve for detection of other lizards that are not in the immediate vicinity. Therefore, the area covered by one in the course of its normal activities may harbor many others, and individuals most of the time are unaware of the others on their home ranges.
Under most circumstances these skinks behave toward each other with tolerance or indifference, but during the breeding season adult males become hostile, and fight on sight. Their reddish facial suffusion serves as a social releaser which elicits hostile behavior and facilitates sex recognition. As the breeding season wanes, the reddish suffusion fades rapidly and male hostility, probably controlled by the same hormonal complex, is likewise suppressed. Hostile behavior is rare in adult females or young at any time.
Combats and pursuits have been observed most frequently the last week of April and especially in the first two weeks of May. At this season funnel traps set along rock ledges often caught two adult male skinks together. In almost every instance one of the two confined males was mutilated, with pieces of skin and flesh bitten from the tail and with chin, snout, and neck scarred; most serious wounds were usually in the sacral region or base of the tail or both. Often the wounds were so severe that the skink died in a short time in captivity and presumably others that were released died also.
On April 28, 1949, a large adult male skink, chased by another, ran out in the middle of a trail and stopped. The pursuer stopped a few inches from it, then after a long pause, retreated in the direction from which it had come. For the five minutes that the pursued skink was watched, it lay motionless, partly hidden by dry leaves, evidently seeking to avoid further pursuit by concealment. I caught it without difficulty, and it seemed weak and dazed, as if injured in the fight. Its reddish suffusion was conspicuous, but not fully developed.On May 3, 1949, an adult male having bright red facial suffusion was observed searching persistently in ground litter; he was seen to find and pursue a female, and to copulate. A few minutes after mating was completed and the pair separated, a second male also searching in the vicinity came within sight of the first one. The two noticed each other at a distance of about 18 inches, indicating their awareness by their more alert, jerky movements, and spasmodic vibrating of their tails. The newcomer darted at the other, and for a moment[53]they dodged and sparred. As one broke away to run, the other seized it by the tail. They were on an exposed tree root about an inch in diameter. The skink that was caught twisted its body around underneath the root and seized its adversary by the tail likewise, so that their linked bodies encircled the root, each squirming to disengage itself from the other’s jaws. After a few seconds they did break apart, and then maneuvered briefly menacing each other at close quarters, but they gradually moved away and lost contact.On May 10, 1949, two adult males were seen to approach each other slowly, pausing for perhaps a minute when they were a little more than one foot apart. Then one edged up to the other, and with a sudden lunge seized it by the head. The one seized broke away with a vigorous jerk, and promptly retaliated by biting the first one’s head. After a few seconds of rapid sparring and thrashing, they broke apart, and one chased the other for several feet until it eluded further pursuit by dodging and hiding.
On April 28, 1949, a large adult male skink, chased by another, ran out in the middle of a trail and stopped. The pursuer stopped a few inches from it, then after a long pause, retreated in the direction from which it had come. For the five minutes that the pursued skink was watched, it lay motionless, partly hidden by dry leaves, evidently seeking to avoid further pursuit by concealment. I caught it without difficulty, and it seemed weak and dazed, as if injured in the fight. Its reddish suffusion was conspicuous, but not fully developed.
On May 3, 1949, an adult male having bright red facial suffusion was observed searching persistently in ground litter; he was seen to find and pursue a female, and to copulate. A few minutes after mating was completed and the pair separated, a second male also searching in the vicinity came within sight of the first one. The two noticed each other at a distance of about 18 inches, indicating their awareness by their more alert, jerky movements, and spasmodic vibrating of their tails. The newcomer darted at the other, and for a moment[53]they dodged and sparred. As one broke away to run, the other seized it by the tail. They were on an exposed tree root about an inch in diameter. The skink that was caught twisted its body around underneath the root and seized its adversary by the tail likewise, so that their linked bodies encircled the root, each squirming to disengage itself from the other’s jaws. After a few seconds they did break apart, and then maneuvered briefly menacing each other at close quarters, but they gradually moved away and lost contact.
On May 10, 1949, two adult males were seen to approach each other slowly, pausing for perhaps a minute when they were a little more than one foot apart. Then one edged up to the other, and with a sudden lunge seized it by the head. The one seized broke away with a vigorous jerk, and promptly retaliated by biting the first one’s head. After a few seconds of rapid sparring and thrashing, they broke apart, and one chased the other for several feet until it eluded further pursuit by dodging and hiding.
Fig. 9.Adult male skinks fighting. A. Menacing approach. B. One has lunged and secured a grip on the other’s side, holding it at right angle. The one caught is unable to flex its body and neck enough to secure a retaliatory grip on the attacker, and must break away by violent thrashing.
Fig. 9.Adult male skinks fighting. A. Menacing approach. B. One has lunged and secured a grip on the other’s side, holding it at right angle. The one caught is unable to flex its body and neck enough to secure a retaliatory grip on the attacker, and must break away by violent thrashing.
On May 12, 1950, my attention was attracted by a rustling in dry leaves. Within a few inches of my foot two adult males were struggling fiercely with jaws interlocked. Sudden violent twisting and thrashing alternated with quiet periods of a few seconds duration, in which the lizards scarcely moved except for heavy panting and twitching of their tails. After perhaps two minutes of fighting, one broke away and ran. For a distance of several feet it was closely pursued by the other, which, however, soon lost contact with it in the rough terrain and surface litter.On May 12, 1951, rustling in dry leaves attracted my attention to two large adult males fighting. For about fifteen minutes that they were observed, they struggled, with neither yielding ground, though they thrashed and rolled about over an area of several square feet. Sometimes they were disengaged for short intervals. Then facing in opposite directions, with their heads side by side, they would snap at each other’s necks and shoulders (Figure 9). Part of the time both males had grips and were biting each other simultaneously, but more frequently one or the other had a temporary advantage. When one secured a grip it would strain to the utmost, biting as hard as it could and lunging forward with frequent short jerks, meanwhile striving to keep out of reach of the[54]other’s jaws. The one caught in the attacker’s grip was usually unable to flex its body sharply enough to reach its opponent at all, or could barely reach it at such an oblique angle that its jaws slipped off the smooth body. Sometimes the one held did succeed in catching the other’s front foot. The one caught in the other’s jaws always succeeded in tearing loose after a short time. In the interval while the attacker rested with jaws partly relaxed, the victim had an opportunity to break away. Even when both were free, they did not obtain grips easily, but often made several unsuccessful lunges and bites, the jaws of each slipping off the firm, smooth sides of its opponent. Sometimes the attacker seized a fold of skin, or sometimes obtained a wide grip on its body. One which had obtained a grip sometimes rolled rapidly, spinning the other around and dashing it against the ground. As these rotations stopped, the victim might come to rest on its back in such a position that it was temporarily helpless, but always broke loose after further struggles. Neither showed any inclination to retreat until finally, when they were interlocked, rolling about almost at my feet, I attempted to catch them. Then they instantly disengaged and rushed away, and one escaped. The one caught had suffered but little injury in the fight. Numerous tooth marks were discernible as minute abrasions on the surface of the scales, but the bony dermal armor had not been perceptibly penetrated during the prolonged and violent struggle.
On May 12, 1950, my attention was attracted by a rustling in dry leaves. Within a few inches of my foot two adult males were struggling fiercely with jaws interlocked. Sudden violent twisting and thrashing alternated with quiet periods of a few seconds duration, in which the lizards scarcely moved except for heavy panting and twitching of their tails. After perhaps two minutes of fighting, one broke away and ran. For a distance of several feet it was closely pursued by the other, which, however, soon lost contact with it in the rough terrain and surface litter.
On May 12, 1951, rustling in dry leaves attracted my attention to two large adult males fighting. For about fifteen minutes that they were observed, they struggled, with neither yielding ground, though they thrashed and rolled about over an area of several square feet. Sometimes they were disengaged for short intervals. Then facing in opposite directions, with their heads side by side, they would snap at each other’s necks and shoulders (Figure 9). Part of the time both males had grips and were biting each other simultaneously, but more frequently one or the other had a temporary advantage. When one secured a grip it would strain to the utmost, biting as hard as it could and lunging forward with frequent short jerks, meanwhile striving to keep out of reach of the[54]other’s jaws. The one caught in the attacker’s grip was usually unable to flex its body sharply enough to reach its opponent at all, or could barely reach it at such an oblique angle that its jaws slipped off the smooth body. Sometimes the one held did succeed in catching the other’s front foot. The one caught in the other’s jaws always succeeded in tearing loose after a short time. In the interval while the attacker rested with jaws partly relaxed, the victim had an opportunity to break away. Even when both were free, they did not obtain grips easily, but often made several unsuccessful lunges and bites, the jaws of each slipping off the firm, smooth sides of its opponent. Sometimes the attacker seized a fold of skin, or sometimes obtained a wide grip on its body. One which had obtained a grip sometimes rolled rapidly, spinning the other around and dashing it against the ground. As these rotations stopped, the victim might come to rest on its back in such a position that it was temporarily helpless, but always broke loose after further struggles. Neither showed any inclination to retreat until finally, when they were interlocked, rolling about almost at my feet, I attempted to catch them. Then they instantly disengaged and rushed away, and one escaped. The one caught had suffered but little injury in the fight. Numerous tooth marks were discernible as minute abrasions on the surface of the scales, but the bony dermal armor had not been perceptibly penetrated during the prolonged and violent struggle.
The eggs ofEumeces fasciatusare like diminutive chicken eggs in appearance. They are white when first laid, slightly translucent when held to the light. Within a day or two after they are laid, these eggs are soiled to a dull tan color, somewhat mottled, as a result of being rolled and dragged about in contact with the floor and wall of the nest burrow. Like the eggs of most other reptiles, those ofEumeces fasciatushave parchmentlike shells. These shells are thin and easily punctured. As incubation proceeds, the egg enlarges by gradual absorption of moisture and the somewhat elastic shell is stretched. An egg left in water for as much as a day does not gain in weight appreciably. Except for occasional abnormal ones, the eggs of any one clutch are notably uniform in size and shape at the time they are laid. As incubation proceeds, some eggs enlarge more rapidly than others, and attain larger ultimate size. Differences in shape also appear, some eggs becoming relatively elongate and thin, while others are thick and blunt. Some become distorted to asymmetrical shapes. In nests that have been deserted by the females, eggs of irregular shape are especially noticeable. It seems probable that the frequent shifting of the eggs by the female prevents unequal drying or stretching in different areas of the shell. Normal young were observed to hatch from grossly misshapen eggs. Under conditions of drought, the eggs may not enlarge normally during the latter part of incubation, and may become indented or partly collapsed, and yet apparently normal younghatch from them. Both in the field, and in laboratory experiments, eggs were found to have remarkable tolerance for excess moisture. After heavy rains of summer thunderstorms, nests were sometimes found to have water trickling through them, and on occasion eggs were found to be partly submerged in water in the nest cavity. Exposed rocks at the heads of small gullies often were chosen by the female skinks as the shelter for their nests. In these situations the nests were exposed to run-off water. In July, 1951, especially, unusually heavy precipitation resulted in the flooding of many nests. In some instances desertion by the females and destruction of the eggs seemed to have been caused by this flooding, even in the well-drained hillside situations where this study was made.
Table 5.—Measurements in Millimeters and Weights in Grams of Eggs in the Same Clutch at Different Stages During Their Incubation, Showing Gradual Increase in Size.
The extent of tolerance to immersion in water probably depends on the stage of development, the temperature, the oxygen content of the water and other factors. One egg was fully immersed for ten minutes on July 20, 1951, then returned to a container with damp soil in the laboratory, where it seemed to develop normally. On July 30 it was opened and found to have a living fetus,[56]which was a week short of hatching. On July 22 another egg of the same clutch was immersed and left in water for 23 hours. On July 30 it was ruptured in handling and found to contain a living fetus. On July 31 two eggs were placed in a dish of water in a refrigerator. On August 5 they were removed and opened. Fetuses were dead and were not appreciably larger than the one of the same clutch in the egg opened on July 31. On August 5 two of the remaining eggs of this clutch were placed in a Petri dish, partly immersed in water, with approximately one-fourth of the surface of each protruding and exposed to the air. Forty-eight hours later it was found that both eggs had hatched. Evaporation had reduced the water in the dish to an amount sufficient to cover only about the lower one-third of each egg. One hatchling was missing, evidently having climbed out of the shallow dish and escaped to the floor. The other was found still standing in the water with its head protruding, and it was lively and in good condition. The remaining four eggs in this clutch, which had been kept in a container of damp earth, were also hatching on this date. On July 10, 1952, an egg in a late stage of incubation was immersed in water in the laboratory. On July 14 when removed, it had fungus growing on it, and was found to have a dead fetus, nearly full-sized.
The extent of tolerance to immersion in water probably depends on the stage of development, the temperature, the oxygen content of the water and other factors. One egg was fully immersed for ten minutes on July 20, 1951, then returned to a container with damp soil in the laboratory, where it seemed to develop normally. On July 30 it was opened and found to have a living fetus,[56]which was a week short of hatching. On July 22 another egg of the same clutch was immersed and left in water for 23 hours. On July 30 it was ruptured in handling and found to contain a living fetus. On July 31 two eggs were placed in a dish of water in a refrigerator. On August 5 they were removed and opened. Fetuses were dead and were not appreciably larger than the one of the same clutch in the egg opened on July 31. On August 5 two of the remaining eggs of this clutch were placed in a Petri dish, partly immersed in water, with approximately one-fourth of the surface of each protruding and exposed to the air. Forty-eight hours later it was found that both eggs had hatched. Evaporation had reduced the water in the dish to an amount sufficient to cover only about the lower one-third of each egg. One hatchling was missing, evidently having climbed out of the shallow dish and escaped to the floor. The other was found still standing in the water with its head protruding, and it was lively and in good condition. The remaining four eggs in this clutch, which had been kept in a container of damp earth, were also hatching on this date. On July 10, 1952, an egg in a late stage of incubation was immersed in water in the laboratory. On July 14 when removed, it had fungus growing on it, and was found to have a dead fetus, nearly full-sized.
The range of temperature tolerance of the embryo is wide, probably comparable to that of the adult. Time required for incubation is dependent on temperature. Persistently wet and cloudy weather in the summer of 1951, keeping temperatures relatively low in nests, was a contributing cause to late hatching that summer. As compared with 1952, hatching was about one month delayed in 1951, but later emergence and breeding accounts for part of the difference. The extent to which low temperature may delay incubation was indicated by the effect of refrigeration on several experimental eggs, as recorded below.
These experiments seem to show that, in the later stages of incubation at least, lowering of temperature to 11° or 12°C. almost halts development of the fetus. Harm does not necessarily result, however, and when again warmed to normal incubation temperatures, the eggs eventually hatch, the incubation period being lengthened by a time approximately equivalent to the interval of refrigeration.
Under natural conditions the time required for incubation probably varies within wide limits, controlled mainly by temperature. No two clutches receive the same amount of heat, as sites differ greatly in extent of insulation, and exposure to sunlight. Each year, earliest appearance of hatchlings is in a warm, sunny situation, and in cooler, well shaded places hatchlings appear somewhat later. Their incubation is evidently somewhat protracted, although later emergence from hibernation and later breeding of adults in these situations might also contribute to the delay.
Widely different incubation periods have been recorded in the literature and the variation probably is not due to temperature alone. Noble and Mason (1933:4) recorded incubation periods for six females from the same locality, and evidently kept under the same laboratory conditions, as 47, 41, 36, 29, 29, and 27 days. Despitethe wide difference in incubation time, all six clutches hatched within a 12-day period from July 5-17. It seems improbable that differences in temperature account for the 20-day disparity between maximum and minimum incubation time, in these females kept under similar conditions. Cagle (1940:229) recorded an even shorter incubation period for one kept in the laboratory, which laid eggs on June 30; hatching occurred on July 23 and 24. Retention of eggs in the oviduct by females kept under unnatural conditions would partly explain their late laying and the short incubation period of their clutches. Such ability to retain eggs in the oviduct while their development proceeds would not be especially surprising inE. fasciatussince its congenerE. lynxeof the highlands in southern Mexico is normally ovoviviparous (Hartweg, 1931:61; Taylor, 1936:171). Cagle did not determine incubation time for any of the natural nests found, but evidently in all of them laying occurred earlier than in the single female brought to the laboratory while still gravid. All the eggs in natural nests found by him were brought to the laboratory and most of them were hatched. Cagle remarked: “The fact that these 26 nests hatched within a period of nine days seemingly indicates that the egg laying period extends over not more than two weeks.”
In the present study no incubation periods so short as those recorded by Noble and Mason, and Cagle, were observed. Incubation times were recorded for clutches both in the laboratory and in the field, but for most of the clutches only approximate incubation periods were recorded. Failure to record the exact date of laying or of hatching, or both resulted from attempts to avoid frequent disturbance of females in their nests, which might have caused them to desert.
One clutch of eggs laid in a terrarium probably on June 17, 1951—possibly a day or two earlier—hatched on July 30, after an incubation of about 44 days. Another clutch, found in a terrarium on July 17, 1951, was estimated to have been laid about a week earlier, judging from the average length (11.8 mm.) and average weight (.55 gm.) of the eggs. These eggs hatched on August 9, a little more than three weeks after their discovery. A clutch found in the field on June 25, 1951, evidently recently laid (average length 12 mm., weight .45 gm.), hatched 41 days later, on August 5. Another clutch found in a terrarium on July 17, 1951, was estimated to have been laid ten days or two weeks before, as the average length was 12.7 mm. The eggs hatched on August 7, three weeks after their discovery. On June 25, 1951, an incomplete clutch of three eggs was found with a female which still had an unlaid egg. The three eggs probably had been laid the same day or the day before. They were kept in the laboratory and weighed and measured at intervals until July 28, 33 days after their discovery when both those that remained were accidentally punctured[59]and found to have nearly full term fetuses. In the field a nest which contained only a gravid female on June 24, 1951, had a clutch of eggs already mud stained and slightly enlarged on June 29. The most probable date of laying was June 26. On August 6 the eggs had all hatched but several young were still in the nest. Probably most hatched on August 5. The incubation time was hence approximately 40 days.On June 21, 1951, a natural nest was found with eggs already somewhat enlarged (12.5 × 8 mm.) and mud stained. This nest was checked from time to time in the next few weeks, and after 39 days, on July 30, it was found that all the eggs had recently hatched, but six young were still in the nest cavity.Another nest was found on June 24, 1951, with the eggs already markedly enlarged (14 × 8 mm.) indicating that laying must have been several days earlier—probably well over a week. Hatching occurred approximately 34 days later, probably on July 28, since on July 26 there was no sign that hatching was imminent, and on July 30 only the empty dried eggshells remained in the nest.
One clutch of eggs laid in a terrarium probably on June 17, 1951—possibly a day or two earlier—hatched on July 30, after an incubation of about 44 days. Another clutch, found in a terrarium on July 17, 1951, was estimated to have been laid about a week earlier, judging from the average length (11.8 mm.) and average weight (.55 gm.) of the eggs. These eggs hatched on August 9, a little more than three weeks after their discovery. A clutch found in the field on June 25, 1951, evidently recently laid (average length 12 mm., weight .45 gm.), hatched 41 days later, on August 5. Another clutch found in a terrarium on July 17, 1951, was estimated to have been laid ten days or two weeks before, as the average length was 12.7 mm. The eggs hatched on August 7, three weeks after their discovery. On June 25, 1951, an incomplete clutch of three eggs was found with a female which still had an unlaid egg. The three eggs probably had been laid the same day or the day before. They were kept in the laboratory and weighed and measured at intervals until July 28, 33 days after their discovery when both those that remained were accidentally punctured[59]and found to have nearly full term fetuses. In the field a nest which contained only a gravid female on June 24, 1951, had a clutch of eggs already mud stained and slightly enlarged on June 29. The most probable date of laying was June 26. On August 6 the eggs had all hatched but several young were still in the nest. Probably most hatched on August 5. The incubation time was hence approximately 40 days.
On June 21, 1951, a natural nest was found with eggs already somewhat enlarged (12.5 × 8 mm.) and mud stained. This nest was checked from time to time in the next few weeks, and after 39 days, on July 30, it was found that all the eggs had recently hatched, but six young were still in the nest cavity.
Another nest was found on June 24, 1951, with the eggs already markedly enlarged (14 × 8 mm.) indicating that laying must have been several days earlier—probably well over a week. Hatching occurred approximately 34 days later, probably on July 28, since on July 26 there was no sign that hatching was imminent, and on July 30 only the empty dried eggshells remained in the nest.
The incubation time approximated six weeks for those nests with most complete records. Under wet and stormy weather conditions such as prevailed in 1951, this may have been the normal incubation period, but in warmer and drier years incubation time is shortened.
In the five-lined skink each adult female normally produces one clutch of eggs annually. The size of the clutch produced is subject to individual variation, and is influenced by the age, size and condition of the female. Geographic variation in clutch size might also be expected. Data were obtained from breeding females killed and dissected, from counts of eggs found in natural nests in the field, and from clutches of eggs laid by females kept in captivity. For the total of 115 recorded clutches represented by the combined data from all these sources, the average number of eggs per clutch was 9.5.
In many females dissected for the purpose of obtaining egg counts, ovulation had not yet occurred. The ovarian eggs present in each of these females included two main size groups, the larger ones in process of maturing and evidently destined for deposition in the current season, and minute, immature ones. A few of intermediate size were always present, however, resulting in uncertainty as to the size of the clutch being produced, especially when development had not proceeded far. Even when the larger eggs formed a fairly distinct size group, some usually were well below maximum size. Relatively high counts of clutches were obtained from these examinations of enlarged ovarian eggs. Evidently development frequently is arrested, and resorption may occur before ovulation. As a result the numbers of ovarian eggs developing are a poor indication of actual clutch size. A series of gravid females were obtainedand examined after ovulation; the numbers of eggs in their oviducts probably indicates accurately the sizes of their clutches. Gravid females taken from their nest burrows and kept in the laboratory in containers with loose damp soil soon excavated new burrows and deposited clutches. Many natural nests were found in the field, and the egg counts obtained from them provided further data concerning clutch size. Although most of these clutches probably had their full complements of eggs, others certainly had sustained losses to predators, or to the females themselves, which may eat some of the eggs. Therefore the average number found is erroneously low. Some of the natural nests found may have contained two or more clutches or parts of them, and the higher counts obtained from natural nests therefore are also questionable.
For different sets of data on clutch size, numbers were as follows:
Table 6. Size of Clutch.
On the average, larger females produce more eggs per clutch than do smaller females. Of 49 females for which measurements were recorded, and which had uterine or large ovarian eggs, 31 were 70 mm. or more in snout-vent length. These 31, mostly or entirely old adults, averaged 9.9 eggs per clutch, whereas 18 others that were 69 mm. or less in snout-vent length, and that must have been mainly or entirely newly matured adults in their first breeding season, averaged only 7.8 eggs per clutch.
Smith (1946:350) states that in the northern part of the range of this skink there is some indication of decrease in size of clutches. This is not well shown by published records. For the southern states, most of the published records of clutch size are by authors who did not clearly distinguish between the three kinds of five-lined skinks, and there is some doubt as to which species is involved in each record. For 56 clutches reported upon from north of approximately latitude 37°, I obtain a slightly higher figure than for 11 clutches from south of this line. Geographic trends are, ofcourse, obscured by individual variation, and perhaps by abnormal clutches produced by individuals kept in captivity.
InTable 7, the figures marked with asterisks pertain to clutches that might have belonged to skinks of the speciesE. laticepsorE. inexpectatussince they were recorded in regions wherelaticepsand in some cases,inexpectatusalso, occurs along withfasciatus. If these questionable clutches are excluded the remaining 55, definitely offasciatus, average 8.48 eggs per clutch, whereas the 12 questionable clutches average 8.42. Both figures are close to the average of 8.82 ± .32 eggs for the 34 natural nests recorded in the present study. For the total of 1661 eggs of 182 clutches, from the combined sample of all available records for clutches found in the present study or reported upon in the literature, the average egg number is 9.13.
Fig. 10.Correlation between size of female and number of eggs in clutch; females in their first breeding season, mostly less than 72 mm. in snout-vent length, produce smaller clutches, on the average, than do larger and older females, but there is extensive overlap.
Fig. 10.Correlation between size of female and number of eggs in clutch; females in their first breeding season, mostly less than 72 mm. in snout-vent length, produce smaller clutches, on the average, than do larger and older females, but there is extensive overlap.
To sum up the available information on clutch size, the number of eggs is most typically 9, 10, or 11 and is more in large old females, than in small, newly matured females. In natural nests, even in those that are successful, there is often some loss of eggs, which are eaten by predators, or by the female herself, with theresult that the egg counts made by various observers average somewhat lower than the numbers actually produced. The loss during incubation cannot be measured readily since it is almost certainly sharply increased by the disturbance entailed in observing nests. Exposing nests, even momentarily, for observation, may result in compacting of the surrounding soil, desiccation, temporary or permanent desertion by the female, and exposure to predation. Some indication of the incidence of loss during incubation might be obtained by counting and measuring the eggs in newly found nests and correlating numbers with size (indicating the length of time incubated).
Table 7.—Numbers of Eggs Per Clutch, Time of Occurrence, Laying Dates and Hatching Dates, as Reported in the Literature by Various Authors.
Lizards and snakes of several different families, are known to brood their clutches of eggs, although the great majority of oviparous forms do not do so. The brooding habit is perhaps best known inEumeces fasciatus, and has been described by many authors. By far the most thorough account is that of Noble and Mason (1933) who observed and experimented upon seven females that laid clutches of eggs in captivity. These females, kept in separate terraria, excavated nest burrows for reception of their clutches, and remained with them throughout the time of incubation. There were three characteristic brooding postures; curved in a semicircle around the clutch, in an S-shaped figure extending among them, or lying straight, either over or among the eggs. The brooding females, taken quietly from their nests without disturbing them, were found to have temperatures averaging .4°C. higher than the nests. Evidently normal room temperatures were maintained in the laboratory where the terraria were kept. The females occasionally left their nests, especially in late afternoon, to wander about the terraria, and to bask in sunlight. While basking, their temperatures averaged 2.7°C. higher than the nest temperatures. The authors suggested that an important function of the brooding female was to transfer warmth from absorbed sunlight to the eggs. They state: “In nature the importance of the mother’s body heat in the incubation of the eggs probably varies greatly with the type of nesting site selected.” They suggest that in clutches deposited in logs or stumps beneath a thin layer of bark exposed to direct sunlight the need for warming by the female would be less.
My own observations do not support the idea that brooding by the female serves to hasten the development of the eggs. Both in the laboratory and in natural nests, clutches deserted by disturbed females hatched and the hatching was not unduly delayed. In the field, females were never observed to bask in the sun beside their nest burrows, and seemingly left them infrequently even to feed. When a female was caught in her nest burrow, her temperature nearly always approximated that of the surrounding earth with which she was in contact. The temperature in each nest depends primarily upon its situation. When the immediate vicinity of the nest receives direct sunlight, the eggs are warmed without the aid of the female, but when there is no sunlight the temperature is much lower. In order to maintain an appreciably higher nest temperature the female would have to make frequent trips to spots perhaps several feet or several yards away to find sunlight. Uponreturning to the nest, her body heat would be quickly dissipated into the eggs and the surrounding damp soil. She would need to shuttle back and forth almost continually between the nest and a spot exposed to sunshine. Cloudy weather often preventing the warming of the eggs by absorption of solar heat prevails during much of the incubation season, in the region of the present study, and probably to an even greater extent throughout the range as a whole.
Noble and Mason state (op. cit.:9) that while in some non-brooding kinds of lizards the eggs are actually damaged by turning, the femalefasciatusfrequently turns her eggs and moves the whole clutch about in the nest cavity. On returning to their nests the experimental females each invariably touched one or more eggs with their tongues as an olfactory test. Eggs of other kinds of lizards not of the genusEumeces, and shellacked eggs offasciatus, or paraffin models of them, ordinarily were discarded immediately after a single touch of the tongue. Eggs of other individuals of the species, and even the eggs ofEumeces laticepswere accepted as part of the brood. Any of the experimental females would quickly retrieve one of her eggs moved a short distance outside the nest cavity. Even if the whole clutch of eggs were scattered about, the female would, over a period of hours, gather the eggs and return them to the nest cavity. This movement of the eggs is accomplished by rolling or pushing them in a loop of the body or tail, or, less frequently, by grasping an egg in the jaws, lifting it, and gently placing it in a new position. Even if the females were blindfolded, they were still able to retrieve scattered eggs, but one in which the tongue tip was experimentally removed showed no further interest in its eggs, presumably having lost the capacity to recognize them by olfactory test.
In the present study clutches unattended by females were observed to sustain heavy losses, both in the laboratory and in the field, and no doubt the attending female performs important functions other than that of warming the eggs. In the damp or wet nest cavity, the eggs tend to adhere to each other and to the earth walls and floor, and become sealed to such surfaces as a result of partial drying, reducing the amount of surface exposed to the air and probably hindering respiration. An eggshell sealed in prolonged contact with the soil tends to rot with the result that it is easily ruptured, and even if it is not broken there is the likelihood of fungi or microorganisms gaining entry and killing the embryo. In many of the eggs that were handled to obtain measurements andweight, rupturing of shells occurred. The shells are tough and elastic to the extent that even when eggs being handled were accidentally dropped on the floor on several occasions, no damage to them resulted. However, slight friction on the shell was sometimes sufficient to puncture one. Particles of sharp rock from the nest cavity may adhere to the shell, and result in rupturing, perhaps at weak spots where prolonged contact with the soil has caused deterioration. The female tends to keep her eggs in a compact cluster, shifting their position frequently so that no part of an eggshell adheres to its surroundings long enough for rotting to occur, and most of the surface of each egg is exposed to the air.
Another important function of the brooding female seems to be that of altering the nest burrow and shifting the eggs so that the effects of unfavorable weather are minimized. The usual response to warm and dry weather is deepening of the nest burrow. A cavity originally in loose soil on the underside of a flat rock, having the eggs in contact with the rock surface, may be displaced downward. The female excavates loose soil from the floor of the burrow and packs it on the top and sides, until the eggs are two or even three inches underground, in a cavity different in position and shape from the original one, although derived from it by gradual stages. In many instances, however, no such response to drying was observed. Probably extensive alteration of the nest burrow no longer is possible after drying of the soil has progressed beyond a certain stage as these skinks are not strong diggers. In some nests that were examined frequently, with resulting desertions by the attending females, the outlines of the cavities became indistinct and the soil around them became dry and packed. In heavy rains, when nest burrows are partly flooded, the females move the eggs to avoid their being submerged. The extent of the female’s activity within the nest burrow is suggested by the glazed condition of the earth walls and floor, and by the mottled appearance which the eggshells soon acquire as a result of being slid and dragged about in the nest cavity.
Still another important function of the female is to dampen the nest burrow to prevent desiccation of the eggs. Even in dry weather, females taken from nests almost invariably voided water in relatively large quantities. They drink dew or other available water, and may void the contents of the bladder to moisten the nest cavity, as on numerous occasions, when nests were exposed by raisingflat rocks covering them, part of the chamber was seen to be recently watered, and distinctly moister than the surrounding soil.
Noble and Mason (op. cit.:16-19) found that brooding females, in the laboratory, would vigorously defend their eggs against small enemies, including mice and lizards and the smaller kinds of snakes that were tested. The female watched alertly as the intruder approached, and attempted to bite it if it came too near or touched an egg. The females failed to defend their nests against persons and against a large blacksnake; when confronted with such a threat, the female would run from her nest cavity to hide. Cagle (1940:228) stated that the brooding females found by him stayed in the nests even when the logs in which they were situated were chopped open with an ax, and that the skinks would attempt to bite when touched with the finger.
In the present study, females whose nests were exposed never made any active attempt to defend them. Many darted away and hid as soon as they were exposed. In other instances, especially when the nest cavity was only partly exposed, from one side, the female cowered back against the inner wall, opening her mouth in threat if closely approached. If further molested she might then attempt to escape. In brooding females a tendency to sluggishness, and an affinity for the eggs delayed the usually speedy escape reactions. The temperature of the female was ordinarily lower than it would have been in the open or on the underside of a flat rock, and this also tended to slow her reactions. Gravid females when exposed in nest cavities that still contain no eggs are similarly sluggish and reluctant to leave differing little or none in behavior from those that have laid their clutches. Usually the female was found with her body encircling the eggs, holding them together in a compact cluster in the center of the nest cavity. The eggs rest in contact with the loose soil on the floor of the cavity, with each other, and with the female’s body in the case of the outer ones of the cluster.
Normal brooding habits proved to be difficult to follow because the females were easily disturbed. In many instances those that had excavated nest burrows, but had not yet laid, deserted the nests after the disturbance involved in raising the sheltering rock. Females that had already laid before discovery of their nests were somewhat less inclined to desert, but many did so.
On numerous occasions, at the time of year when most females are gravid and are staying in nest burrows, I have discovered well formed nest burrows empty and seemingly deserted, with no femalein evidence nearby. In some instances the female may have been out foraging or basking although she was not seen, and in other instances the female may have been killed by a predator or eliminated by some other accident. However, it seems that gravid females frequently do desert their original nest burrows, for one cause or another, and excavate new ones. Such desertions were noted many times in the females observed on the study area, where the disturbance from my own activities in raising the sheltering rocks may have caused shifts, but it was probably not the sole motivation. One female shifted approximately 120 feet, to excavate her second nest burrow in a site that was damper and more heavily shaded than the first site. This was in the notably dry summer of 1952. Most of the favorite sites under flat rocks in open situations, that were used in 1950 and 1951, were not occupied in 1952 or 1953, although several females did use them for original excavations, which were deserted before laying, as drought conditions developed. In the summers of 1952 and 1953 nests were difficult to find, and those discovered were on the average deeper and better protected than those found in other years.
As compared with other North American lizards in general,Eumeces fasciatusis notable for the relatively exposed and superficial situations chosen as nesting sites. However, it occurs in a climate of high humidity; in contrast, the great majority of our lizards live in arid climates where the eggs are in much greater danger of desiccation, and require better shelter to maintain the humidity at a sufficiently high level. Accounts in the literature and observations in the present study indicate that these skinks exercise a wide range of choice of nesting sites. Ruthven (1911:264) stated that in northern Michigan nests were usually in decaying logs; occasional nests were found in burrows in sand, but invariably decaying wood was present in or around at least part of the nest.
Blanchard (1922) mentions a nest in Tennessee that may have been made by either this species orE. laticeps“in a hollow in a dead willow tree about fifteen feet from the ground buried in the loose, damp, rotted wood.” Noble and Mason (op. cit.:16) quote Blanchard (in litt.) that in northern Michiganfasciatusnests in logs that are exposed to sunlight. Conant (1951:31) stated that several clutches of eggs found in Ohio were an inch to six inches beneath the upper surface of the log or stump which sheltered them. Evans and Roecker (1951:70) record finding two incubating females inside rotten pine logs, in Ontario. Cagle, studying this species near Elkville, Illinois, in oak-hickory woods, found 25 natural nests ofwhich three were in loose soil among the roots of a fallen tree, another was under loose bark of a log, and the remainder were all in cavities of partly decayed logs. Bishop (1926:119) recorded finding a female with a clutch of eggs beneath damp boards at Quicksand, Breathitt County, Kentucky.
In the present study, more than one hundred natural nests were found, of which just one (containing two clutches of eggs) was in decaying wood beneath the bark of an old log. All other nests were beneath rocks. On the University of Kansas Natural History Reservation, where most of the nests were found, the policy is not to tear apart decaying logs; therefore the nests probably present in such situations were not ordinarily found. On several occasions groups of hatchlings were seen on logs within which they probably had hatched. In the area of the study, however, decaying logs are scarce. The hardwood forests consist mostly of young trees that are second growth on cutover areas or pioneer on areas that were previously grassland. Because of frequent cutting there are few old mature trees, and logs have not accumulated on the forest floor. In northeastern Kansas, nesting in logs is comparatively rare. On wooded slopes and the edges of level hilltops, the flat limestone rocks that are often abundant provide preferred nesting sites. Even on collecting trips off the Reservation, where stumps and logs could be torn apart and searched, flat rocks were found to provide the main source of nesting sites. These nest rocks varied from less than an inch in thickness to nine inches or more, and from a few inches in diameter to three feet or more. Some were resting loosely on the surface of the soil and others were deeply sunken, on one side. Some were in situations exposing them to nearly the maximum amount of sunshine whereas others were in sites nearly always shaded. The varied character of the nesting sites chosen demonstrated a wide range of tolerance for temperature, moisture, and other factors, in the gravid and brooding female and in the developing embryo.
As already mentioned, Noble and Mason (op. cit.:9-10) noted that females would accept and brood the eggs of other individuals just as readily as their own, and several writers have reported gregarious nesting habits, with two or more females occupying either the same nest cavity, or separate cavities that were in close proximity. For instance, Cagle wrote that among the small logs he found to contain nests, four logs each contained one nest, five each contained two nests, and two each contained three nests, while three other nests were found within an eight inch square area in loosesoil among tree roots. McCauley (1939:93) in Maryland found three females brooding clutches of eggs, which totaled 20, and which were so near together that there was uncertainty as to which clutch certain eggs belonged in.
The gregarious nesting habit may be of benefit in permitting maximum utilization of choice nesting sites, where such sites are in short supply in an environment otherwise favorable. Also, the gregarious tendencies make possible more continuous guarding of the eggs against such natural enemies as can be repulsed by the female, since each female occasionally interrupts her brooding to bask or forage.
Many of the nests that I found were in close proximity to others. Often two nests, and sometimes even three, were found beneath the same rock, and sometimes a distance of only two or three inches intervened between the separate clutches. It seemed, however, that in almost every instance each female had excavated a separate nest chamber originally. In some instances adjacent nest chambers communicated with each other.
On July 13, 1948, a communal nest was discovered beneath loose bark of a decaying elm log. There were 22 eggs in the combined clutch, and there were two females in the vicinity. The bark was raised on several different days to examine the eggs, and one or both females always were found with the eggs.
On June 10, 1949, at the pond rock pile, a flat rock was turned and an unusual nesting aggregation consisting of a minimum of eight females, and probably more than ten, was found. The nests were somewhat disturbed by movement of the rock. The ground beneath was honeycombed with tunnels connecting the flask-shaped nest cavities, which were in part open to the rock surface on their upper sides. Clutches of eggs numbered 13, 12, 11, 8, and 6 (the last attended by a female which appeared to be still distended with several more unlaid eggs). Of five other females taken, two had laid and three were still gravid. Of the five clutches, two had eggs noticeably larger than those in the other three, and with their shells mottled brown from adhering earth. These nest cavities were about half an inch deep and two to three inches wide. The females were released as soon as they had been examined. One female moved about over the nest areas exposed, and evinced interest in a lone egg which had become separated from the others. She moved up to it, standing high off the ground, with her head turned at right angles to her body as if preparing to push the egg forward inthe angle thus formed, and tested it with her tongue, but then she became alarmed and left the vicinity. The flat rock was lowered over the nests again with a minimum of disturbance.
On July 9, 1949, the flat rock covering the nests was raised again. Most of the eggs had hatched. Two broods of hatchlings were still in their respective nest cavities, and one entire clutch had not begun to hatch although its incubation was nearly completed. Three eggs ofScincella lateralewere found mixed with theEumeceseggs. One of these was opened to verify their identity; the other two hatched a few days later in the laboratory.
The following selected excerpts from my field notes, setting forth histories of several nests, so far as they were known, give some idea of the types of nesting sites chosen, the behavior of the females, and the hazards to which the eggs are exposed.