George A. Bartholomew

Control of Changes in Body Temperature, Metabolism, and Circulation by the Agamid Lizard, Amphibolurus barbatus

I N VIEw of the importance of behavior in regulating the body temperature of lizards (Cowles and Bogert, 1944) it is not surprising that little attention has been given to the contributions of physiology to ameliorating the effects of environmental temperature on body temperature in these animals. However, limited capacity for physiological thermoregulation may exist, and since such a capacity could have theoretical implications for the evolution of homeother-

The Water Economy of Land Birds

TERRESTRIAL life is an aqueous phenomenon. Although the physiological and ecological roles of water are of paramount importance in the lives of all organisms, ornithologists have paid little attention to the water requirements of birds, except inferentially with regard to distribution and habitat preferences. It is an interesting commentary on the fads and fashions of science that prior to World War II many hundreds of papers had been published on the food habits of birds, but only a handful of papers had given even semi-quantitative attention to the no less important problems of water economy. The inevitable preoccupation of government biologists with possible economic importances, together with the relatively simple technique of stomach analysis, early led to many studies of food habits. In contrast, water economy, while of basic biological significance, has no obvious economic implications, and its analysis requires the labor of maintaining live birds under controlled or semi-controlled conditions. During the past decade we have, together with various colleagues, undertaken a series of studies surveying the water economy of land birds in order to gain some preliminary insights into the ways different species have resolved the problem of maintaining a water balance. Although our studies have raised more questions than they have answered, they do allow the establishment of appropriate ecological and physiological perspectives. The purpose of this review is to sum up the conclusions from exploratory studies, in the hope that they may serve as a guide to more sophisticated physiological experiments and for more quantitative and precise ecological analyses. Our point of view is primarily ecological, and we shall confine our remarks to wild species of land birds. Readers interested in the domestic fowl should consult Sturkie (1954), and those requiring a broader physiological coverage should see Chew (1961). Historical summary.-Fewer than a dozen publications bearing specifically on the water economy of wild birds appeared prior to 1950. Buxton (1923) broached the problem of the water relations of desert-inhabiting birds and mammals, and suggested that some species might depend upon metabolic water. Allens (1925) semipopular treatment of avian biology contains a brief section on drinking habits, and Stresemann (1927) in his monumental treatment of birds for the Handbuch der Zoologie noted the general lack of information on avian water economy. Apparently as a

Size, Body Temperature, Thermal Conductance, Oxygen Consumption, and Heart Rate in Australian Varanid Lizards

the largest living and the largest T extinct lizards. The living members of the family occur in tropical and warm-temperate parts of the Old World and are usually assigned to a single genus, Varanus. Since the Australian varanids used in the present investigation share the same general body form and habits, we have placed primary emphasis on physiological differences associated with size rather than differences between species. The species studied are alert, fast-moving, diurnal scavengers and predators which eat mammals, birds, reptiles, frogs, and large insects. In comparison with most other lizards, we found them difficult to approach and capture. The V. gouldii and V. varius were captured in the vicinity of Brisbane. The V. punctatus were captured in an area of dry Acacia scrub in southwestern Queensland, and the single specimen of V. acanthurus was taken in northern Queensland near Charters Towers.

Oxygen Consumption during Resting, Calling, and Nest Building in the Frog Physalaemus Pustulosus

Males (mean mass 1.7 g) called and amplexing pairs built foam nests in respirometer chambers. Mean oxygen consumption (V̇o2) of resting males during the day was 0.26 ml h⁻¹, and at night it was 0.53 ml h⁻¹. Mean V̇o2 of males that could hear other males calling but that were not themselves calling was 0.70 ml h⁻¹. Mean V̇o2 of calling males was 1.13 ml h⁻¹. The energy cost per call (whine) decreases as whine rate increases. Mean V̇o2 per frog during nest building was 2.03 ml h⁻¹. The individual energy cost incurred by male and female during nest building could not be separated. The data on oxygen consumption during sustained calling and nest building offer an opportunity for measuring voluntarily sustained elevated levels of aerobic metabolism in anurans. During calling and nest building mean aerobic metabolic scope was 1.23 and 1.67 ml h⁻¹, respectively. The corresponding factorial scope of about 5.7 is within the range of published values for anurans undergoing forced activity. Because there is a high energy cost associated with reproductive activities in Physalaemus, and presumably in other anurans, any interpretations of aerobic and anaerobic metabolic patterns in frogs and toads should take into account reproductive, as well as predatory and escape, behavior.

Energetics of Locomotion and Load Carriage and a Model of the Energy Cost of Foraging in the Leaf-Cutting Ant Atta colombica Guer

Standard rates of O₂ consumption (V̇o2) and net, gross, and minimum costs of transport (NCOT, GCOT, and Mrun) were measured in the leaf-cutting ant Atta colombica. Both closed (running wheel respirometer) and flow-through (treadmill) systems were used. The relation between body mass (.004–.035 g) and standard V̇o2 in workers was V̇o2 = .074 M.62 where V̇o2 is ml h⁻¹ at 28 C and M is mass in grams. When combined with published data for 30 ant species, at 20 C this equation becomes V̇o2 = .137 M.838. Equations that allow calculation of NCOT and GCOT from body mass and running speeds are presented. NCOT in A. colombica at 28 C was 18.6 ml O₂ g⁻¹ km⁻¹ (mass .015 g, running speed 5.2 cm s⁻¹). Both NCOT and GCOT decreased with increasing body mass. Load carriage decreased running speed and increased NCOT proportionally to the increase of body mass + load mass. Cost of transporting a unit of load and a unit of body mass were therefore equivalent. Mrun, was 10.1 ml O₂ g⁻¹ km⁻¹ (n = 11, mean mass .0314 g), which does not differ significantly from values predicted on the basis of published equations relating Mrun to body mass in vertebrates and insects. A model is developed to predict the energy costs of foraging and maintenance of an Atta colony. The cost of maintaining a 100-m trail with a traffic rate of 60 loaded and 60 unloaded workers min⁻¹ at 28 C was approximately 2.2 W.

Heating and cooling rates, heart rate and simulated diving in the Galapagos marine iguana

Abstract 1. 1. During enforced submergences of 30–50 min, the animals remained quiet. Bradycardia developed slowly following submergence and conspicuous arrhythmia appeared. Bradycardia ended almost immediately following the termination of submergence. 2. 2. In both air and water the lizards heated approximately twice as rapidly as they cooled. 3. 3. Heart rate at any given body temperature was much slower during cooling than during heating, suggesting that circulatory adjustments are important in controlling rate of temperature change. 4. 4. Minimum heart rates in air increased with increasing temperature, and at all temperatures the smaller animal had a more rapid heart beat than the larger one. 5. 5. Ecological and comparative aspects of the responses of the marine iguana are discussed.

BODY TEMPERATURE, OXYGEN CONSUMPTION, EVAPORATIVE WATER LOSS, ANDI HEART RATE IN THE POOR-WILL

The physiology of the Poor-will (Phalaenoptilus nuttallii) is of unusual interest. Not only is it one of the very few birds which can undergo long periods of dormancy comparable in most respects to mammalian hibernation, but over much of its summer range it is exposed to severe conditions of heat because of its habit of spending the daylight hours, even in the desert, sitting quietly in the open. During the past year we have had the opportunity to make a series of observations on two captive, adult PIoor-wills, one (P. n. hueyi) captured by Mr. Donald Schroeder in the Coachella Valley, Riverside County, California, and the other (P. n. californicus) found in a torpid condition in Eagle Rock, Los Angeles County, California, by Mrs. Gerald Massey. Both birds were maintained for many months in captivity and were fed on a diet of meal worms (Tenebrio larvae) and canned cat food. The limited information on the physiology of Poor-wills has previously been summarized (Bartholomew, Howell, and Cade, 1957; Howell and Bartholomew. 1959) and need not be reviewed here.

Body Temperature, Oxygen Consumption, and Heart Rate in Three Species of Australian Flying Foxes

on body temperatures of flying foxes over a narrow range of ambient temperatures, and their data suggest that at least two genera, Pteropus and Rousettus, have considerable thermoregulatory ability. Robinson and Morrison (1957) and Morrison (1959) have presented measurements of body temperature and a few determinations of oxygen consumption in Pteropus poliocephalus. Their data, although obtained from a single individual weighing less than half the normal weight of adults of this species, indicate a substantial capacity for homeothermy. The present study undertakes a survey of some of the more obvious aspects of thermoregulation in three species of flying foxes and examines possible correlations between the physiology and ecology of these animals.

Relation of Oxygen Consumption to Body Weight, Temperature, and Temperature Acclimation in Lizards Uta stansburiana and Sceloporus occidentalis

BROWNE, W. R. 1945. An attempted post-Tertiary chronology for Australia. Proc. Linn. Soc. New South Wales, 70:v-xxiv. BURBIDGE, N. T. 1953. The genus Triodea R. Br. (Gramineae). Australian Jour. Bot., 1:121-84. CROCKER, R. L., and WOOD, J. G. 1947. Some historical influences on the development of the South Australian vegetation communities and their bearing on concepts and classification in ecology. Trans. Roy. Soc. South Australia, 71: 91-136.

Temperature Regulation, Hibernation, and Aestivation in the Little Pocket Mouse, Perognathus longimembris

The little pocket mouse, Perognathus longimembris , was selected for a study of temperature regulation because (1) it is one of the smallest North American rodents (adult weight, 6.5 to 10 grams); (2) it is a member of the highly specialized family Heteromyidae; (3) it is locally very abundant; (4) it is readily maintained in captivity; and (5) nothing was previously known about its temperature regulation. Despite the abundance of pocket mice, very little has been published on the physiology of any member of the genus Perognathus . Hall (1946) adduced circumstantial evidence for the occurrence of hibernation in some species of pocket mice and its absence in others. Scheffer (1938) found that Perognathus parvus showed an irregular dormancy during the winter but he determined no body temperatures. We are unaware of any other published information concerning temperature regulation in the genus. P. longimembris occurs commonly in eastern and southern California, extreme northwestern Mexico, and throughout much of the Great Basin, reaching the northern limit of its distribution in southeastern Washington. It lives from below sea level in the Salton Sink to an altitude of at least 6500 feet in the Sierra Nevada. The present study was made between June and September, 1955, and is based on 23 adult animals trapped in the Antelope Valley and Walker Pass areas of the Mohave Desert of southern California. The captive animals were individually housed in glass jars or plastic boxes partly filled with fine sand. They were given no water and remained in excellent condition throughout the study on a diet of mixed bird seed. All temperatures were measured with 30 gauge copper-constantan thermocouples coated with baked insulating enamel and connected to a recording potentiometer. Oral and rectal temperatures were taken with thermocouples inserted to a depth of at least 2 cm.; …