Sceloporus Graciosus Research Articles

Observations on the Behavior and Interactions of Two Sympatric Sceloporus in Utah

Sagebrush lizards (Sceloporus graciosus) were more wary and less prone to climb trees than fence lizards (Sceloporus undulatus). Males of both species were considerably more active than females in May. The evidence for species discrimination by the males was inconclusive, but males never confused the sex of a conspecific, and both sexes showed some ability to distinguish individual mates. Males courted females and defended territories both during and after the reproductive season. Mates may form long-term pair bonds. Some males of both species were polygynous; others monogamous. Frequency of assertion displays was correlated with distance traveled. Push-up displays of the two species were distinct. This paper reports preliminary findings of the social behavior and interactions of Sceloporus undulatus (the fence lizard) and Sceloporus graciosus (the sagebrush lizard) where they are sympatric in southern Utah. The study area was located in the Kolob section of Zion National Park, Washington Co., Utah, at an elevation of 6200 ft (1888 m). The area includes a small temporary stream bordered on the E by a steep sandstone slope with little vegetation cover, and on the W by a lava outcrop, supporting a heavy growth of scrub oak (Quercus sp.), maple (Acer sp.) and serviceberry (Amelanchier sp.). Although both sagebrush lizards and fence lizards are abundant on the study area, fence lizards are confined to an island of scrub growth associated with the stream. Sagebrush lizards are more widespread through the area and are the most abundant lizard at this elevation. In May 1969 the study area was divided into 24 quadrats (20 ft on each side) marked by numbered stakes to facilitate measuring lizard location and activity. In August 1969 26 quadrats were added, increasing the area to about %2 acre. All lizards residing on the 50-quadrat area were captured by hand or noose; each was marked by clipping various combinations of toes and by painting a distinctive design on its back according to standard proceduire (Tinkle, 1967). I measured the snout-vent length in mm of each lizard, then released it at the location of capture. I spent about 80 hr in periods ranging from 2 to 9 hr following the various marked individuals. In August lizards captured in May were recaptured, remeasured, repainted and released. Data were recorded on a Magnavox portable cassette tape recorder. I spent 16-27 May and 3-11 August 1969 in the field. Sagebrush and fence lizards, though similar in appearance in southern Utah, can be distinguished easily by the dorsal color of the head; that of a sagebrush lizard is patternless but that of a fence lizard includes several bold narrow stripes and bands. Adult sagebrush lizards also are smaller and stockier than fence lizards. The average snoutvent length of the adult sagebrush lizards I measured was 57 mm; of fence lizards, 66 mm. There seems to be no sexual dimorphism in

Energy Utilization in the Lizards Sceloporus graciosus and S. occidentalis

Three Sceloporus graciosus which gained weight (+ 0.37 g) during measurement assimilated 83-88 cal/g/day when maintained on a Tenebrio larvae diet. One S. graciosus which maintained constant body weight assimilated 73 cal/g/day. Five S. occidentalis that had a mean weight gain of 3.70 g had a mean energy assimilation of 36 cal/g/day. It was calculated that a male S. graciosus, feeding only on Tenebrio larvae, would ingest 78,000 cal during its first three years of life, of which 64,000 cal would be assimilated. Ap- proximately 61% (39,000 cal) of the total energy assimilated would be used in metabolism. * * * The subject of energy budgets and measurements of energy assimilation of reptile species has not been extensively studied. However some reports have appeared giving estimates of energy utilization. McNab (1963) using the respirometry data of Dawson and Bartholomew (1956) and the temperature data of Bogert (1949), calculated the daily energy expenditure of Sceloporus occidentalis. Johnson (1966) estimated the daily energy assimilation of three species of lizards. Alexander and Whitford (1968) calculated the energy requirements of a population of Uta stansburiana.

Temperature and Energy Characteristics of the Sagebrush Lizard (Sceloporus graciosus) in Yellowstone National Park

The mean cloacal temperature for 41 Sceloporus graciosus in the field was 30.9*C. Both the mean air temperature one inch above the ground (23.7*C) and the mean substratum temperature (25.7*C) were significantly lower than the mean cloacal temperature. The mean cloacal temperatures of discrete spring, summer, and fall samples of lizards collected in 1966 measured in a laboratory temperature gradient (N = 58, 70 and 60 respectively), differed significantly from each other, with the spring sample having the lowest mean (28.9*C) and the summer sample the highest (32.3*C). The mean critical thermal maximum of a sample of 14 lizards collected August 1965, was significantly higher than the mean critical thermal maximum of a sample of 10 lizards collected in June 1966 (43.6 vs 42.6*C). While the mean critical thermal maxima of three samples collected in 1966 were not significantly different from each other, they, as well as the mean temperatures obtained from the samples in the thermal gradient, followed the general seasonal trend in temperatures. Oxygen consumption measured at 30*C with a Warburg apparatus was approximately 30% of the value indicated for most species of lizards. Mean fat storage on 7 September 1966, was approximately 23% of the total dry body weight for both juvenile and older lizards. Using estimates from oxygen consumption and fat loss, an adult lizard produces 2000-2800 cal during a hibernation period of 220 days.

Geographic Variability of the Lizard, Sceloporus graciosus Baird and Girard, in the Eastern Part of Its Range

Field studies and examination of museum material reveal a complex distributional, morphological, and ecological situation in Sceloporus graciosus. Geographic dines occur for dorsal scales, scales around midbody, snout-vent and tail lengths, color, and blotch pattern. Two differentiated geographic isolates are recognized, one inhabiting geyser basins and thermal areas in Yellowstone National Park, the other inhabiting sand dunes in southeastern New Mexico and western Texas. The north-

Patterns of Social Behavior of Merriam's Canyon Lizard (Sceloporus M. merriami-Iguanidae)

The social behavior of a group of 19 canyon lizards, Sceloporus merriami, was observed in a large enclosure. The pattern of movements and the cadence of these movements in the display sequence are species-specific. The domi- nant male is responsible for the majority of aggressive actions such as displaying, courting, fighting, and chasing in the group. Subordination is indicated by retreat, submission and reduced activity. Dominance was shared by two males, and when they were removed a new dominant male arose and maintained his dominance when the previous dominants were returned. A courting male nods rapidly while follow- ing a female and attempts to get a biting grip on the skin of her shoulder region to effect copulation. One observation suggests that the female may sometimes initiate courtship and mating. The canyon lizards observed in this study were captured in early April, 1960, along the canyon walls of the Devils River, 10 miles north- west of Del Rio, Val Verde County, Texas. They were kept in cages until early June and then released in an outdoor enclosure at the University of Oklahoma Biological Station in south-central Oklahoma. The square enclosure of galvanized sheet metal measured 10 feet on a side and was 3 feet high. The enclosed area contained fine sand vary- ing in depth from two inches near the sides to a one foot dune in the center. A row of six cinderblocks was stacked three, two, one along the top of the dune while stacks of two only were placed near three corners. A six foot by three inch pole was erected near one side and small pieces of wood were scattered over the area. Water was provided in a large sunken clay dish. Insect food was provided daily from sweep nettings. Other lizard species present in the enclosure included Scelo- porus woodi, Sceloporus graciosus, Sceloporus scalaris, Uta stansburi- ana, Urosaurus ornatus and Urosaurus graciosus. All individuals were color marked for individual recognition. Re- cording methods included still and movie photography and tape re- cordings. Observation periods were from 8:00 a.m. to 11:00 a.m. and 4:00 p.m. to 6:00 p.m., when the lizards were most active. Observa- tions began on June 10, when 19 canyon lizards (9 females, 10 male) were released into the enclosure, and continued on 25 different days until July 28 when observations were terminated.

Additional Observations on Home Ranges and Longevity in the Lizard Sceloporus graciosus

IN the summer of 1942, I marked a population of mountain swifts, Sceloporus graciosus, in a section of the Chaos Jumbles of Lassen Volcanic National Park, California. Individual lizards were rendered permanently recognizable by removal of toes in varying combinations. In 1942 and in subsequent years data have been gathered on this original group and additional lizards have been marked. In this way, it has been shown that the species at Lassen is of sedentary habits, individuals tending to remain for many years in relatively circumscribed areas, usually less than 100 feet in greatest dimension. This fact and others having to do with rate of replacement in the population, growth, and habits have been reported in previous papers ( Stebbins, 1944; Stebbins and Robinson, 1946). The present report records additional information relating to the fate of marked animals.' From August 6 to 10, 1947, in the area of study delimited in 1942, a total of 73 individuals was captured and then released. Of this number, 8 had been marked in 1942 and 10 in 1945. The remainder were unmarked. Persistent search of the area over a period of three months in 1942 brought to light 119 individuals exclusive of the season's young. Assuming a constant population size through the years, it is probable that 13 (11 per cent) of the original group was still present as based on the percentage of animals marked in 1942 among the random sample. In the same manner the number of individuals of the group marked in 1945 and still in the area may be roughly estimated. Ten of the 35 marked were recaptured. This number is approximately oneseventh of the random sample obtained in 1947. On the basis of probability, 17 individuals would be expected in the assumed total of 119, approximately 50 per cent of the original number. In 1945 it was estimated that one-third of the group marked in 1942 was present after a lapse of three years. Thus a decline to about one-half the number marked in 1945 after two years is reasonable. These estimates suggest that the number present in 1942 may have been halved during the first two years, was reduced to one-third the third year, and declined to about one-tenth by the fifth year. The rate of decline indicated is, of course, entirely a matter of speculation, since the actual number of individuals within the study area during these years was not known.

Lizards as Predators of the Beet Leafhopper1

In Utah during the past three years, 2659 lizards have been collected and their stomachs examined. Of 1573 Uta stansburiana stansburiana taken among host plants of the beet leafhopper, 915 stomachs contained a total of 9322 specimens of Eutettix tenellus (Baker). Of 213 Sceloporus graciosus graciosus taken among host plants of tenellus, 59 stomachs contained 239 specimens of this pest. Other lizard species in which one or more specimens of tenellus were found include S. elongatus, Phrynosoma douglassii ornatissimum, P. platyrhinos, and Eumeces skiltonianus .