Harold Heatwole

Environmental Factors Influencing Local Distribution and Activity of the Salamander, Plethodon Cinereus

The Red-backed salamander, Plethodon cinereus Green, has a broad geographical distribution reaching from the Gaspe Peninsula to northern Minnesota, then south to Georgia and South Carolina (Grobman 1944, Bishop 1947). It occurs in a variety of habitats including northern hardwoods (Creaser 1944, Test 1952), oakhickory forest (Test and Bingham 1948, Test 1955), pine barrens (Burger 1935), and birch and mixed forests (Cochran 1911). It is found under stones, in and under logs, and within the leaf litter and other organic layers of the forest floor. In order to understand the factors affecting microdistribution of such a eurytopic species, it is desirable to carry out studies in different habitats where different restrictive conditions are likely to be operating. The present investigation of local distribution of P. cinereus was carried out in 2 such habitat types during the summers of 1957 and 1958.

Thermal Ecology of the Desert Dragon Amphibolurus inermis

Amphibolurus inermis occurs throughout Australia except for the eastern third of the continent, the north—central coast, and the southwestern tip. It inhabits sandy soils. Body temperature rises in the morning, levels off and remains rather constant between 1000 and 1600 hr, and falls after 1600 hr. Thermoregulation involves changes in location and posture, color change, basking, burrowing, shade—seeking, and panting. The level of temperature maintained depends on geographic locality and immediate weather conditions and may depart widely from the temperature preferred in a laboratory gradient. The relative importance of specific behavioral responses varies with locality; burrowing and shade—seeking may be interchangeable. Amphibolurus inermis functions either as a thigmotherm or a heliotherm depending on local conditions and time of day. It is one of the most heat—resistant species known; the mean body temperature which causes loss of coordination is 48.5° C, and the lethal temperature is 49.3° C. Because of the extreme environments it occupies, A. inermis has narrow minimum thermal safety margins even though it has high temperature tolerances. Burrows tend to be located near thermoregulatory perches. When the sun—perch and the shade—perch are close together, an individual may have only one burrow; if the perches are further apart, a burrow will usually be located near each. If widely separated, auxiliary burrows may occur between the two types of perches. Burrows sometimes become too hot to serve in thermoregulation. Active individuals are found at all hours between sunrise and sunset in summer. However, individuals may seek shelter at midday. In winter the activity period is restricted to a few hours at midday. It is suggested that preferred temperatures may shift during the day, but that these levels cannot always be maintained. Head temperatures may be regulated more precisely than those of the body.

Relationship of Escape Behavior and Camouflage in Anoline Lizards

BROWN, B. 1905. The osteology of Champsosaurus Cope. Mem. Am. Mus. Nat. Hist. 9(1): 1-26. Fox, R. C. AND M. C. BOWMAN. 1966. Osteology and relationships of Captorhinus aguti (Cope) (Reptilia: Captorhinomorpha). Univ. Kans. Paleontol. Contrib., Art. 11, pp. 1-79. PIVETEAU, J. 1955. Traite de paleontologie. V. Amphibiens, reptiles, oiseaux. Masson, Paris. PRICE, L. I. 1935. Notes on the brain case of Captorhinus. Proc. Boston Soc. Nat. Hist. 40(7):377-386. ROMER, A. S. 1956. Osteology of the reptiles. Univ. Chicago Press, Chicago. RUSSELL, L. S. 1956. The Cretaceous reptile Champsosaurus natator Parks. Bull. Nat. Mus. Canada 145:1-49.

Spatial and Temporal Variability in Defoliation of Australian Eucalypts

Insect defoliation is commonly associated with and assumed to be a cause of mortality in Australian eucalypts, particularly in rural regions where trees suffer from the eucalypt dieback syndrome. To test this, leaf growth and defoliation were measured in the canopies of Eucalpyptus trees from June 1982 to June 1986, and related to tree health and eucalypt dieback. Over 5000 leaves were monitored, including replicates of branches, canopy heights, individual trees, species, and sites. Three types of sites were selected, representing the most common conditions in the eastern Australian tablelands: woodlands (comprised of healthy trees but with slight signs of dieback), healthy trees in pastures, and dying trees in pastures. Within each site the commonest native tree species were selected for study; species were not always the same between adjacent sites because of interspe_kw canopy See full-text article at JSTOR

Some aspects of the association of cattle egrets with cattle

Abstract Cattle Egrets associated with cattle receive the two-fold advantage of obtaining 1 1 4 to 1 1 2 times as much food and expending approximately 2 3 as much energy per unit time as non-associated egrets. Egrets tend to associate with cattle that are grazing in the sun rather than with cattle in the shade or those engaged in other activities.

Studies on anuran water balance—I. Dynamics of evaporative water loss by the coquí, eleutherodactylus portoricensis

Abstract 1. 1. Rate of loss depends on activity, body size and posture. Activity increases rate of loss up to 200 per cent above standard rate, largely through changes in exposed surface area (maximum effect of 130 per cent) and gradient upsets (maximum effect 30 per cent). Effects of elevated metabolism probably account for the rest. 2. 2. Standard rate of juveniles, even when expressed on the basis of exposed surface area, was approximately double that of adults. 3. 3. No evidence was obtained that the skin itself exerts any physiological control over evaporative loss.

Biogeography of the Puerto Rican Bank: Species‐Turnover on a Small Cay, Cayo Ahogado

The equilibrium species—number of plants on Cayo Ahogado, a small sand cay east of Puerto Rico, is 11.2 if all species are considered, and 6.8 if only established species are counted. Establishment is defined in terms of reproductive success and presence on the island for at least two consecutive visits. There were only five species in the permanent flora. Species—turnover rates of plants were high, migration being on the average 14.4 species/year (all species), or 1.6 species/year (established species only). Extinction rates were 17.2 and 0.8 species/year for total species and established species respectively. Immigration is chiefly by flotation, particularly of propagules released by flood waters in Puerto Rico; extinction is caused by failure to find suitable habitat, wave erosion, and hurricanes. Nine individuals of three species of lizard arrived, probably by flotsam as time of arrival correlated with flooding in Puerto Rico, and persisted for varying times up to 5 months. No reproduction occurred. Species turnover of invertebrates was high. Eighty—one species (77 terrestrial, 1 marine water strider, and 3 semiterrestrial crustacea) were recorded from the cay. Equilibrium number was 9.8 for established species and 14.2 for total species. Direct flight was probably the most imporrant mode of immigration for the entire fauna because of the large number of strong fliers among the ephemerals. If only established species are considered, flotsam transport becomes important. Human transport and passive dispersal by wind were relatively insignificant. Trophic structure of the fauna remained relatively constant although taxonomic structure varied. It is postulated that species—numbers on small cays are determined in part by the type of trophic structure which can be built upon available energy reserves, and that establishment of immigrants is influenced by whether they fit into the trophic scheme.

Some Aspects of the Thermal Ecology of Puerto Rican Anoline Lizards

Despite occupancy of nearly identical geographic ranges and similar thermal en- vironments, Anolis cristatellus maintains slightly higher body temperatures than A. stratulus. Within a given species, tolerance to low temperature was dependent on body size. Interspecific differences were not attributable to size; species from high altitudes were more tolerant to cold than those from lower elevations. Lowland species were more tolerant of high temperatures than upland ones. Preferred environmental temperatures in a laboratory gradient were higher than mean TB in the field. The theory is advanced that differences in type of activity period account for many apparent differences in thermoregulatory ability among lizards. * * * Rands scatter diagrams indicate that body temperatures of lizards (TB) were on the average, several degrees higher than those of the air (TA), the magnitude of the difference being approxi- mately the same throughout the range of conditions under which measurements were taken (sunny days) and similar for all species studied. The lone exception was A. gundlachi, in which body tem- peratures more closely approximated air temperatures than in the other species. This is probably because A. gundlachi occupies interiors of forests at higher altitudes and consequently has less opportunity than the other species to raise its body temperature by absorption of solar radiation. His work was not repeated in detail in the present study although some body temperatures were measured with emphasis on A. stratulus and A. cristatellus in an area where both species inter- mingled and occupied similar, if not identical, thermal environments. Body temperatures were measured with a Schultheis thermometer inserted cloacally. Inas- much as a lizard attempting escape may alter its body temperature by moving into an area with

Biogeography of the Puerto Rican Bank: Flotsam Transport of Terrestrial Animals

Of 59 pieces of flotsam picked up at sea 0.5—16 km from its nearest probable origin, 25% contained at least one live terrestrial animal and 6% had three or more species; one green plant contained 12 species. In many cases a number of conspecific individuals occurred in the same drift item. The animals represented included 19 families of insects, as well as psuedoscorpions, snails, spiders, mites, millipedes, isopods, and worms. Some families were represented by several (up to five) species. Eight drift items recovered approximately 120 km from the nearest land lacked terrestrial animals. A piece of bamboo which washed up on the beach of Cayo Ahogado contained a dipteran and a beetle. Flotsam transport is clearly a significant biogeographic factor among the islands of the Puerto Rican Bank. See full-text article at JSTOR

Ecology of Three Sympatric Species of Parasitic Insects of the Genus Megarhyssa (Hymenoptera: Ichneumonidae)

Three species, Megarhyssa atrata lineata, M. macrurus lunator, and M. greenei greenei were studied in beech—maple forests in Michigan . All are diurnal with similar activity patterns except that female M. atrata maintain a high degree of activity later in the day than do the others. Saturation deficits above 10 g/m2 inhibit activity whereas normal summer daytime temperatures do not. There does not seem to be a significant difference between time of emergence of females and of males in the spring, nor are there differences in seasonal occurrence of the various species except that M. Greenei may persist slightly longer in the fall. Insects of both sexes and of all species tend to return repeatedly to the same log or stump with but a limited amount of movement between sites. Adults rest on the undersides of beech and maple leaves during inactive periods. Since there are more such places than individuals to use them, competition for shelter does not seem to occur. Neither do adults compete for food. The larvae of the three species are largely segregated ecologically in that they parasitize different segments of the host population. This depends on the facts that (1) the adults select a host larva at a depth in the wood so that complete insertion of the ovipositor at right angles to the surface of the wood will just reach it, (2) the ovipositors of the different species are of different lengths, and (3) the host larvae maintain themselves at about the same depth in the wood for most of their larval period. There is succession of species on a given log but not to the extent that the three species would be ecologically segregated without the above mechanism. The sequence of species in the succession seems to depend on differences in ovipositor length. Females are usually more abundant on logs when a species is invading a new log; males are usually more numerous in the declining phase. Adults can live at least 27 days. Predators in the area were robber flies and perhaps a chipmunk. Incidence of parasitism of Tremex by Megarhyssa was 26.7% in part of a log which was examined.