Tom J. Cade

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

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.; …

Water Economy and Metabolism of Two Estrildine Finches

BE ING a closely related group of species with an extensive tropical and subtropical distribution in the Old World, Africa, southern Asia, and Australia, the estrildine finches provide an opportunity to study physiological attributes which may have become adaptively modified in various populations for specific environmental conditions within this large range. For this initial study, the zebra finch (Taeniopygia castanotis) of Australia was chosen as a xerophilous form to compare with the tropical black-rumped waxbill (Estrilda troglodytes) of Africa, because it seemed likely that these two species might reveal the maximum difference in physiological adjustments for the regulation of water to be found within the subfamily Estrildinae.

Sea-Water and Salt Utilization by Savannah Sparrows

deserts, sea water offers the only potential supply of drinking water to terrestrial animals, but the degree to which it is utilized is uncertain. It has become apparent in recent years that many birds which successfully occupy desert regions show no conspicuous physiological adaptations in their water economy (Bartholomew and Dawson, 1953; Bartholomew and Cade, 1956). The present consensus (Axelrod, 1950) is that the widespread deserts of western North America are relatively recent developments. Coastal marshes, on the other hand, must have been in existence since long before the origin of birds and thus represent a habitat of great antiquity. It is therefore of both evolutionary and physiological interest to investigate the water economy and salt metabolism of passerine birds that characteristically occupy salt marshes in which fresh water is scarce or absent and to compare them with related forms which live in desert regions. The savannah sparrow (Passerculus sandwichensis) presents unusually favorable opportunities for studying the use of sea water by a passerine bird. This species is a wide-ranging, polytypic group composed of both migratory and resident races. Some forms (P. s. beldingi, P. s. rostratus) are restricted to salt marshes and marine beaches and are characteristically associated with salt-impregnated ground (Grinnell and Miller, 1944, p. 489). Savannah sparrows nest in damp habitats such as marshes, the edges of streams, or, as is sometimes the case in P. s. nevadensis, around alkaline sinks in the desert. Several migratory

Nasal Salt Secretion in Falconiform Birds

Falconers have long known that various raptors, especially accipiters and eagles, exude a clear fluid from their nares while eating. We were reminded of this fact while handling a melanistic Gabar Goshawk (Micronisus gabar), which we trapped in the Kalahari Desert in August 1964. As the hawk ate his prey, the small droplets of fluid that collected on our gloves had a strong salty taste. This discovery led us to look for nasal secretions in 16 species and 10 genera of Accipitridae and in eight species and three genera of Falconidae. We have studied behavioral and physiological aspects of nasal secretion in these raptors with reference to Schmidt-Nielsens (1964) hypothesis regarding the general necessity for birds to utilize an extrarenal mechanism of salt excretion, as an adjunct to efficient water reabsorption from the cloaca in concentrating uric acid, and also in connection with the overall water economy of carnivorous birds.

Effects of Sodium Chloride on the Water Consumption of House Finches

T qIIS preliminary study of the role of sodium chloride in the water economy of house finches (Carpodacus mexicanus), which occur commonly in the deserts of North American, was undertaken to determine the concentrations of salt water which these birds will drink and the maximum concentrations on which they can exist. Water is one of the environmental factors which control the occurrence of birds and determine their mode of life over large areas of the world. Since the limited amount of surface water available in arid regions is often highly mineralized, a knowledge of the salt and electrolyte metabolism of this species should contribute to an understanding of the adaptations of birds to the desert environment. In a recent paper (Bartholomew and Cade, 1956) we reported on the water consumption of the house finch and summarized what was known about water loss and water consumption in wild birds. In the absence of heat stress, house finches drink an amount of water equivalent to about 20 per cent of their body weight per day, and at high temperatures some individuals drink as much as 100 per cent of their body weight per day. At moderate temperatures they can live I This study was aided in part by a contract between the Office of Naval Research, Department of the Navy, and the University of California (NR 160-171).

IN MEMORIAM: SALLY HOYT SPOFFORD, 1914–2002

the last systematic collecting of Australian birds by an overseas institute, collecting in all parts of the continent and enriching the British Museum collection of Australian birds by some 6,500 specimens (skins, skeletons, and fl uid). The leader of the fi rst expedition in 1962–1963, Jim’s party discovered a new species of bird (Hall’s Babbler) in Queensland. In that expedition, his wife Betty accompanied him as doctor and caterer for the team. They liked the outdoor life in Australia, so they settled in Brisbane upon his retirement. Jim became the inaugural president of the new Queensland Ornithological Society in 1969, led the Society in its formative years, and was elected an Honorary Life Member. He also produced the fi rst handbook of Australian birds (Birds of Australia: A Summary of Information, with a chapter on the origin of Australian birds by Dom Serventy and illustrations by Peter Slater) in time for the 16th International Ornithological Congress held in Canberra in 1974. His efforts to popularize bird study are seen in the publication of Bird Biology (1959), Bird Behavior (coauthored by D. Goodwin and H. E. Adler, 1962), Bird for Beginners: How Birds Live and Behave (1980), and The Illustrated Dictionary of Australian Birds by Common Names (1987). Jim never lost the modesty and quiet passion cultivated in his native country. His gracious appreciation of Australian generosity expressed through dour looks was seldom recognized. Queensland Ornithological Society (Birds Queensland) is planning the publication of a special issue of its journal Sunbird to commemorate his contributions to Australian ornithology.