Showing papers in "The Condor in 1966"

Sexual Dimorphism and Differential Niche Utilization in Birds

Abstract: Adaptive radiation has been defined as the evolutionary divergence of members of a phyletic line into different niches or adaptive zones (Mayr, 1963:633). Although it has been customary to think of adaptive radiation solely in terms of species or races, a growing body of evidence indicates that some degree of radiation occurs also within populations, as individuals come to occupy different subniches or adaptive subzones, subdividing and, perhaps, expanding the total niche or zone utilized by the population. Probably all species show some degree of ecological variation, either polymorphic or continuous. But this phenomenon is being studied in only a few groups of organisms, notably in Drosophila, in which chromosomal polymorphism has been interpreted as a. means of adaptation of populations to heterogeneous environments (Dobzhansky, * 1961, 1963, 1965). Theoretical bases for research on ecological variation in animal populations have been provided by Ludwig (1950), Levene (1953)) da Cunha and Dobzhansky (1954), Dempster (1955), Li (1955), Carson (1959), and Levins (1962, 1963). In birds, as in other vertebrates, the sexes usually differ in size if not also in proportions of body parts, including those used in feeding (Amadon, 1959) ; and, especially where the degree of sexual dimorphism, which is a form of polymorphism (Ford, 1961: 12), is marked, it seems probable that the morphological divergence has ecological significance in adapting the sexes to different subniches. However, there is only an occasional reference in the literature to sexual dimorphism in relation to niche utilization (e.g., Pitelka, 1950; Rand, 19.52), and, in general, the whole problem of ecological variation in populations has been neglected by vertebrate ecologists. The primary purpose of this report is to present evidence of an adaptive function of sexual dimorphism in size in woodpeckers by relating degrees of morphological dimorphism and sexual divergence in foraging behavior in two melanerpine species, the strongly dimorphic Hispaniolan Woodpecker (Centurus striatus) of Haiti and the Dominican Republic and the moderately dimorphic Golden-fronted Woodpecker (Ce&zmus awifrons) of continental North and Central America. In addition, the paper surveys other evidence that sexual dimorphism in birds is related to differential niche utilization. Finally, some evolutionary aspects of sexual dimorphism and ecological variation are considered.

An Analysis of the Body Temperatures of Birds

Abstract: Recently there has been much work done on the energetics of homoiotherms. One parameter of energetics, body temperature, is relatively easy to measure and, thus, has been often studied. An analysis of the body temperatures of mammals was proposed by McNab (1966), but none has been made of bird temperatures. The purpose of this report is to analyze the factors responsible for the level of body temperatures of birds.

Annual Gonadal Cycles and Pituitary Gonadotropins in Zonotrichia leucophrys gambelii

Abstract: The essential role of the anterior pituitary gland in the development and the function of the avian gonad has been recognized for more than three decades. However, little is known concerning annual variation of gonadotropic function in species with marked gonadal cycles. The only extensive information available appears to be that of Greeley and Meyer (1953) who investigated the gonadotropic activity of the anterior pituitary in relationship to the annual testicular cycle in Ring-necked Pheasants (Phasianus colchicus) held in captivity under semi-natural conditions. In order to extend our understanding of the regulation of the hypothalamo-hypophysio-gonadal axis in birds under natural conditions, we have investigated the annual cycle of pituitary gonadotropic potency in relation to gonadal cycles in free populations of the White-crowned Sparrow, Zonotrichia leucophrys gambelii Nuttall. Such data are also indispensable in the interpretation of the results of experiments conducted under controlled conditions. The annual testicular cycle of Whitecrowned Sparrows has been investigated by Blanchard and Erickson (1949), by Oakeson (1954), and by Oakeson and Lilley (1960). Our data extend these investigations, and describe also the annual ovarian cycle.

Food of nestling yellow-headed blackbirds, Cariboo parklands, British Columbia.

Abstract: Several techniques have been used for collecting food samples from wild birds, and the errors inherent in these different methods have been discussed by Hartley (1948). In the case of small passerines, which cannot be induced to disgorge the contents of their stomachs, food brought to the young has been collected either by the use of artificial nestlings (Promptow and Lukina, 1938; Betts, 1954, 1956) or by placing around their necks light metal collars too narrow to permit the nestlings to swallow the food brought by the parents (Kluijver, 1933; Lockie, 1955; Owen, 1956). Thus far, all successful uses of artificial nestlings have been with holenesting species. In this study I have collected food from nestling Yellow-headed Blackbirds (Xanthocephalus xanthocephalus) and Redwinged Blackbirds (Agelaius phoeniceus) by wrapping segments of pipe cleaners around their necks (Willson and Orians, 1963; Willson, 1966). Attempts to induce the adults to feed artificial nestlings have failed, and Evans (1964) also was unable to obtain samples in this manner from sparrows. The pipe-cleaner method has several important advantages. With minimal experience neck bands can be installed rapidly and adjusted to the size of the nestling. Moreover, the same nestlings can be sampled repeatedly during their stay in the nest. However, there are some important disadvantages that must be kept in mind when evaluating the data. First, I have thus far been unable to obtain good samples from nestlings younger than three days old. All attempts have resulted either in slippage of the food past the band or in strangulation of the young. Therefore, data are restricted to the period after the first few days of nestling life. Since the food brought during the first few days might be expected to differ from the food brought to older young, this is an important limitation. Second, there is abundant evidence that at times, even with older nestlings, some food slips past the neck bands, although with careful installation this can be minimized. There is, at present, no way of measuring the extent of this loss. But smaller food items are probably more likely to pass than larger ones, so that samples may be biased in favor of larger food items. Also, if the rate of delivery has been rapid or the bands have been left on longer than usual, the young frequently cough up the food. Normally this can be picked up from the bottom of the nest or the surface of the water underneath; but it is possible that some of the food is lost or that it may even be eaten by the adult birds. Finally, although I have no direct evidence, it is possible that after food has accumulated in the throats of the nestlings for a time they may not beg as vigorously, with the result that the feeding rates of the adults decrease. Conversely, the lack of food in the stomach may induce more vigorous begging. It is also possible that the adults may eat some of the food they have brought if nestling response is reduced. At present it is impossible to determine the magnitude of these effects. Thus, although I cannot determine the absolute rate of delivery from these food samples, it is possible to obtain information concerning relative rates of delivery provided that the errors mentioned above are equally important at all times of the day. Since this assumption appears reasonable, the data will be used to draw conclusions about relative rates of delivery of food to the nestlings and relative compo-

Energy Requirements for Egg-Laying and Incubation in the Zebra Finch, Taeniopygia castanotis

Abstract: The energy required for nesting activities, particularly egg-laying and incubation, has seldom been determined quantitatively for wild birds. Riddle et al. (1934) studied food consumption and weight variation of common pigeons at the various stages of the reproduction cycle. Kendeigh (1941) indicated that the initial development of the gonads does not demand great energy expenditure and that the principal energy drain comes in the female with the formation of the eggs. Kendeigh et d. (1956) developed the hypothesis that the size and number of eggs are influenced by the energy resources of the bird during the three days immediately preceding laying. Kendeigh (1963) has also shown that incubation requires an expenditure of energy in the form of heat in excess of that normally lost in the birds’ metabolism. An equation was derived for calculating the amount of heat applied to the eggs during incubation. The equation includes several empirical constants, values for which are given for the House Wren, Troglodytes aedon, but the equation may be applied to any other species if the constants for that particular species are determined. In the above studies, estimations of the energy requirements for egg-laying and incubation were based on indirect measurements. In the present work, the energy cost of egg-laying and incubation has been measured by a direct experimental procedure using the Zebra (or Chestnut-eared) Finch, Taeniopygia castanotis (= Poephila gzlttata) . A knowledge of this energy cost is important. If a species is unable to mobilize sufficient energy in any region to carry on reproduction, then the species will be excluded from that region, except as a transient. Likewise, the timing of reproduction will be regulated to conform with the time of the year when energy is sufficient. For these experiments, advantage was taken of the egg-laying productivity and the readiness of the Zebra Finch to incubate in captivity. Some of the birds used in the experiments had been kept previously for about two months in a cage 124 cm wide, 185 cm high, and 306 cm long. Several extra pairs were bought from dealers in Topeka, Kansas, and in Chicago, Illinois. All the birds were put together in the large cage for at least three weeks before they were placed in the experimental cages. The Zebra Finch is distributed throughout Australia. The species inhabits dry areas but not deserts (Marshall, 1959), where there is shrubby vegetation for cover and nesting. It is well known (Frith and Tilt, 1959) that Zebra Finches breed after a period of rainfall. Robinson (1956) also claims that in northwestern Australia there are breeding peaks in both spring and autumn. In southwestern Australia the failure of winter rains and the low temperatures prevent winter reproduction not only in Zebra Finches but also in most other birds (Serventy and Marshall, 1957). The wet season (White, 1924) coincides with the period of highest temperatures and longest days. This is the summer period which starts in October and ends in March. June, July, and August, when the Zebra Finch stops breeding, are the coldest months (Frith and Tilt, 1959).

An Additional Character Linking Ratites and Tinamous, and an Interpretation of their Monophyly

Abstract: For more than a century there has been a debate as to whether the so-called ratites-the ostriches, rheas, emus, cassowaries, and kiwis, plus the extinct moas and elephant birds-were of common ancestry, or had evolved convergently from unrelated stocks. Superimposed on this argument was a debate as to whether these flightless birds had ever had flying ancestors, or had evolved directly from preflying ancestral forms. The latter school of thought has been largely discredited, but has had a few persistent advocates (see Verheyen, 1961, and papers cited therein). The debate as to monophyletic versus polyphyletic origin of the ratites, however, has continued, with outspoken adherents to either position. The volant tinamous were thought long ago by various authors to have some kind of affiliation with the flightless ratites, but their relationships could not be clarified until the “preflying ancestor” theory of ratite origins was disposed of. Much of the history of these debates, together with useful bibliographies, can be found in recent publications by Bock (1963), Meise (1963), and de Beer (1956, 1964), and details need not be recapitulated here. It is oversimplifying to state that the monophyletic and polyphyletic schools of thought have alternated in popularity, as at any one time adherents to both could probably be found. We suspect that some of the early classifiers might have admitted that the ratites could have arisen independently from unrelated flying ancestors, but that these birds were placed together in avian classifications merely for lack of any evidence as to what such ancestors may have been. McDowell (1948) concluded that the palaeognathous arrangement of the bones of the palate, long considered one of the major characters held in common by the ratites, was a heterogeneous composite. His work gave strong impetus to the polyphyletic school, which gave rise to some widely quoted papers (see Mayr and Amadon, 1951:3, and Stresemann, 1959:275), and reached its zenith in the dogmatic statement of the late Rene Verheyen (1960:293), part of which reads “. . . it is already firmly established that close relationship between the orders of Ratitae is pure fiction . . . .” Some of the recent synthetic and secondary literature has reflected this viewpoint. For example, Lagler et al. (1962:412) state, in a section entitled “Parallel evolution or convergence” in an ichthyology text: “The distribution of the large, flightless birds, the Ratites . . . is a classic example. Once thought to be intimately related and hence all placed in a single group, these birds are now knozm [italics ours] to have sprung from divergent ancestors . . . .” See also, in this connection, Mayr et al. (1953:42-43). As various kinds of evidence are reexamined and new data forthcoming, however, students of the ratites are returning to the theory that the similarities among these birds are, indeed, to be attributed to common ancestry (Sibley, 1960; Bock, 1963; Meise, 1963). There are obvious difficulties inherent in making comparisons between external features of adult birds as large as most ratites. During a study of natal downs, we handled and compared downy young of several ratites and tinamous, and we were struck by the constancy of a character of the bill, visible on adults but seen to much better advantage on small young. We believe this to be an additional piece of evidence favoring the theory of monophyletic origin of ratites and tinamous, and one

A Viewpoint concerning the Significance of Studies of Game Bird Food Habits

Abstract: In the past six or seven decades there have been numerous studies concerning the food habits of North American game birds. However, in recent years food studies have become somewhat passe, partly as a result of the belief that little useful information is gathered that can be used in the development of wildlife management plans (Kalmbach, 1954). In place of understanding game bird food requirements, wildlife managers have turned to various forms of habitat manipulation to increase populations, and too often have found their efforts to be futile. I can cite two examples from personal experience. First, an extensive water development ("gallinaceous guzzler") program in southern Nevada in the late 1940's failed to provide a hoped-for population expansion in Gambel's Quail (Lophortyx gambelii) because much of the area affected by development lacked an adequate food resource, and food is even more important than water to the desert quail. These quail can exist quite well in the proper environments without preformed drinking water but not without food (Gullion, 1960; Hungerford, 1962; Gullion and Gullion, 1964). Second, we still apparently know too little about the food requirements of Ruffed Grouse (Bonasa umbellus), the voluminous studies of Bump et al. (1947) and others, notwithstanding, to understand fully the reasons for the periodic drastic fluctuations of population size, or to develop effective forest management plans that have resulted in significant, sustained increases in Ruffed Grouse populations. P, Three basic factors are believed to be responsible for this situation. First, most game bird food studies have been based on samples obtained in the fall from hunterkilled birds, and therefore represent items taken at the time of year when the greatest amount of food is normally available, both in quantity and variety. These fall-taken samples are often comparatively meaningless, even if carefully evaluated in terms of the variety and abundance of foods locally available to the birds (and this frequently is not done).' Second, most studies are short-term, representing one or two years' thesis research, or a short-lived (2 or 3 years) intensive state game research project. Third, seldom are the food studies related to the status of the population of birds being sampled; that is, the investigators do not specify whether the population is static, rising, or falling; the density of the species (for comparison with other areas); and how the physical condition of the birds sampled compares with a normal or standard condition. With these shortcomings it is hardly surprising that little has been learned that can be used significantly in developing long-range management programs for many native game birds. Indeed, there have been some published food studies of imported game birds that, in view of the species' failures to become established, can best be interpreted as reflecting diets that could not sustain the birds. Food studies are needed that critically sample local game bird populations during times of stress as well as during periods of population upswing as was done by Lehmann (1953). Too often it has been assumed that a wide diversity of foods available, and taken, represents a desirable and adequate food situation, at least among the gallinaceous game birds. As Errington (1936:356) pointed out long ago, "The feeding tendencies of vertebrates generally may be rather indiscriminate ... " The presence of certain food items in the digestive system, even in abundance or with

Nasal Salt Secretion in Falconiform Birds

Abstract: 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-Nielsen's (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.

Avian Plumages and Molts

Abstract: The primary function of feathers is flight, but th'ey also insulate and protect the body from the physical environment. The reptilian scales from which they evolved have this as their principal function. Perhaps a reptile that was becoming warm blooded evolved frayed scales to provide better insulation and these in turn proved to be preadapted for flight. In birds that long ago lost the ability to fly such as the kiwis (Apteryx) the vaned structure of the feathers of flying birds has deteriorated. Feathers are collectively called plumage, just as the hairs of a mammal make up its pelage or fur. The term is also used for particular "ensembles" of feathers such as "downy plumage" and "male breeding plumage." Recently Humphrey and Parkes (1959) have proposed a new usage for the word "plumage," and the entire concept of plumages is discussed at greater length later in this paper. If all birds had uniformly black feathers like a crow and if selection for flight and insulation were the only influencing factors, what direction would the study of feathers take? The adaptations, especially of the wing and tail feathers, for flight would be of paramount interest: first, the general adaptations and then such specialization as notched outer primaries and forked tails, which aid aerial stability or maneuverability. Then one would turn to the original function of feathers and other epidermal structures, that of protecting the animal from the environment. This function has been retained in feathers, and, as suggested, may have preadapted them for flight. But not all birds are black. Feathers often have complex patterns, culminating in such amazing structures as the vanes of the peacock (Pavo), which are, as Darwin noted, one of the problems posed by nature to the theory of natural selection. This variety in color pattern extends to different parts of the bird's body and to the individual bird at different ages and seasons. That the shape and texture of feathers is as adaptable as their color scheme is shown by the extravagantly modified plumes of egrets and birds of paradise. Even the normal structure of the feather may be lost, as in the celluloid-like head feathers of the Curl-crested Araqari (Pteroglossus beauharnaesii) or the plumes of the King of Saxony's Bird of Paradise (Pteridophora alberti). Feathers basically adapted for flight maneuverability such as a forked tail may secondarily be modified for display, as in the Greater Racket-tailed Drongo (Dicrurus paradiseus). In several instances, for example the tail feathers of snipe (Gallinago), feathers have become modified for producing sounds used in sexual display. It is clear, then, that feathers and plumage are extremely responsive to selection. What are the secondary functions they have acquired, over and above the primary ones of flight and insulation? Camouflage. Streaked grassland birds, sand-colored desert birds, and white arctic birds are well-known examples of concealing coloration. Sometimes the camouflage is heightened by behavior as when a bittern (Botaurus) stretches head and neck skyward, thus blending with the marsh vegetation. The dark hues of forest birds (Gloger's Rule), the white of arctic birds, and the sandy hues of desert birds are probably primarily adaptations for concealment. Display. The important relation of feathers to display cannot be overemphasized. (a) Displays related to reproduction. We do not need to outline the formal classifica-

Annual Cycle of Reproduction and Molt in Gambel Quail of the Rio Grande Valley, Southern New Mexico

Abstract: Studies of seasonal cycles in various aspects of the biology of wild-bird populations are necessary for understanding the ecology of particular species. Such studies also may yield results of general interest, indicating the nature and variety of adaptations to various climatic regimes and revealing something of underlying physiological interplay among environmental stimuli, endocrine activity, gametogenesis, molts, and behavior.

Vocalizations and Behavior in Captive Gambel Quail

Abstract: The life history and ecology of the Gambel Quail (Lopkortyx gambeZii) are fairly well known. Got-such (1934) has written the best life history of the bird in Arizona, and Edminster (1954) has summarized information on the species for its entire range. But except for Gullion’s work (1962)) relatively little has been done on the calls and social behavior of the bird. This paper catalogs and describes the calls and associated behavior of Gambel Quail. A detailed comparison of calls in this group will appear later. Most of the birds used in the study were trapped in the wild in southern Utah, but some were raised in captivity. The latter were more tame in their reactions to humans. The birds were held and observed in two pens made from poultry mesh. One pen was 40 X 60 X 7 feet; the other was 40 X 12 X 7 feet. Both were subdivided into smaller subpens by poultry mesh partitions. The birds were clipped on one wing to prevent flight over the three-foot-high partitions. Food and water were freely available in standard containers; a roofed shelter and brush provided cover and loafing spots. To minimize disturbance from passersby, canvas screens enclosed the area. Observation and recording of calls were done from a blind. Calls and verbal notes were recorded on a Webcor Model EP 2612-1 tape recorder in the blind. Most recordings were made at a tape speed of 3.75 inches per second; the microphone was an Electra-Voice Model 664, hung in the center of the pen. When possible, behavioral situations were manipulated to have the calling bird in the subpen containing the microphone. Birds were separated by placing them in nearby brooder houses; depending on which of several houses were used, auditory as well as visual isolation was obtained. Spatial isolation only was achieved by putting the wing-clipped bird in an adjacent subpen. Samples of calls were analyzed on a Kay Electric Co. Sound Spectrograph. Included in this paper are typical sonograms of all but one of the calls observed. These were judged typical on the basis of visual inspection, or by measurement of physical characteristics. The tape recordings and the majority of observations were made in the summer of 1962. Preliminary observations began in spring, 1961. The senior author was a participant in the National Science Foundation Undergraduate Research Participation Program. Additional support was provided by NSF Grant No. G-21348, and by the Division of Research, Utah State University. Bird calls may be placed in the following categories, which are based largely on the scheme suggested by Collias ( 1960) : ( 1) Feeding relationships; (2) Responses to enemies; (3) Reproductive behavior-(a) Sexual phase: Courtship and agonistic behavior, and (b) Parent-young phase; (4) Group activity. We will first discuss group activity and then proceed to more complex patterns. The calls, the circumstances in which they have been observed, and their possible functions are summarized in table 1.

Biology of the Mountain Bluebird in Montana

Abstract: It is generally believed that the Eastern Bluebird (SiaZia sialis) has been declining in numbers over its range for the past several decades (see Amadon, 1966). Although no exact censuses exist, many observers are convinced that there has been a similar decline in the populations of the Mountain Bluebird (Sialia currucoides) in Montana. Since this opinion is so widely held, the possibility of a decrease in the numbers of Mountain Bluebirds must be seriously considered and is worthy of investigation. In addition, data on all aspects of the biology of this species are fragmentary. Therefore, I studied the Mountain Bluebird from 1961 to 1963 for various periods between March and October near Calvert, southern Cascade County, Montana, in order to investigate its breeding biology and, if possible, to identify factors that might affect its population level. In order to insure the presence of a breeding population during the years of study, 29 nesting boxes were erected between 1960 and 1963. The inner dimensions were 5 X 5 X 8 inches (length X width X height) with an entrance hole 1.5 inches in diameter 6 inches above the bottom of the box. The boxes were placed 4 to 5 feet above the ground on fence posts, utility poles, and trees. Each was readily accessible and was usually examined at intervals of not more than one week during the nesting season. A coding system was devised to provide the following information about each box: year of occupancy (61, 62, or 63), serial number of box (1 through 29), whether the observations were of a first (a) or second (b) brood, and if the box was used by a new pair ( 1) or by a pair including a new mate of a bird already nesting in the box in the same year (2). For example, the designation 62-513-2 identifies observations made in 1962 at box number 5, involving a second brood produced by a pair in which one member had not previously occupied the box in 1962. Omission of the third (a, b) or fourth (1, 2) elements of the code means that the information is not relevant or is not known. Both Fish and Wildlife Service bands and colored plastic bands were used. By trapping adults in nest boxes during the nest-building period through the nestling period and by banding nestlings, data were obtained on 126 bluebirds, 27 pairs, and 21 nests.

Agonistic Behavior and Vocalizations of Orange-Chinned Parakeets in Captivity

Abstract: The behavior of neotropical birds has not been as extensively investigated as that of birds common to boreal and austral faunas. This is due not to lack of interest, but to factors of inaccessibility and distance from most institutions actively engaged in avian research. Thus, in 1963 and 1964 I undertook a study of captive Orangechinned Parakeets (Brotogeris jugularis), a gregarious, neotropical species. The aim of the study was to investigate social interaction and communication between individuals, within pairs, and in different-sized flocks. Special attention was given to how certain "emotions" (e.g., levels of aggression, annoyance, appeasement) are communicated among members of a flock, and what integrated function this communication has in the daily activity and social structure of these birds. Orangechinned Parakeets, as well as many other psittacids, become relatively well adjusted to captivity, and thus afford a nearly ideal situation for studies of this kind. The present report deals with the agonistic behavior and vocal repertoire of Orange-chinned Parakeets. The two topics are interdependent. A subsequent report will describe epigamic and reproductive behavior. The distribution of Orange-chinned Parakeets. Brotogeris jugularis is found in arid tropical woodlands, from southwestern Mexico (Guerrero) south over the Pacific slope of Central America to northern Colombia and Venezuela (Peters, 1937:206207). According to Eugene Eisenmann (personal communication) the local distribution in Central America is from the lowlands to about 3000-feet elevation. In

Migrants in the Galapagos Area

Abstract: The last comprehensive report on migrant birds in the Galapagos region was published more than 30 years ago by Swarth (1931) who excluded most of the procellariiform species previously considered by Gifford (1913) and Loomis (1918). Subsequently, a number of records obtained at sea and on the islands were reported by various authors, chiefly Fisher and Wetmore (1931), Swarth (1933), Murphy (1936), Lack and Venables (1940), Fleming (1950), and Harrison (1962). During the 12-year period, 1952 to 1964, visits were made by one or more of the present writers to all the principal islands of the Galkpagos Archipelago (fig. 1), with numerous opportunities to observe and to collect at infrequently visited coasts and inland areas. The purpose of this report is to bring together all records of Galipagos migrants that have accumulated since 1931 and thereby make available a more up-todate summary of species occurrences, distribution, and relative abundance. The term "Galapagos area," as used here, includes the islands and intervening waters of the Galipagos Archipelago, plus a circular band of open ocean, approximately 200 miles in width, measured from the perimeter of a circle that passes through Culpepper and Hood islands (fig. 2). Thus this region in the eastern equatorial Pacific encompasses a circular area of 385,000 square miles, and is approximately 700 miles in diameter. The easternmost end of Chatham Island (Punta Pitt) is 502 miles west of Cape San Lorenzo on the Ecuadorian mainland (Slevin, 1955:99). Guadalupe Island (Mexico), Socorro Island in the Revillagigedo Archipelago, and Clipperton atoll are approximately 2700, 1700, and 1300 miles, respectively, northwest of Culpepper Island in the Galkpagos. To the northeast, Cocos Island (Costa Rica) and Malpelo Island (Colombia) are approximately 425 and 630 miles, respectively, from Tower Island in the Galhipagos. The nearest land west of Galkpagos is the island of Fatu Hiva in the Marquesas, about 2800 miles distant. The islands of San Felix and San Ambrosio (Chile) and Sala-y-Gomez and Rapa Nui (Chil6) are about 1600 miles to the SSE and SSW, respectively, of Galkpagos. The perimeter of the Galipagos area comes to within about 140 and 320 miles of Cocos Island and the nearest Ecuadorian mainland, respectively. To be sure, the limits of the Galkpagos area have been chosen somewhat arbitrarily, since they cut across several oceanographic and meteorological provinces (Abbott, MS; Alpert, 1963; Murphy, 1936). Nevertheless, it is because of this unusual setting that so many interesting avian distributional discoveries are occurring and will continue to do so. The need for more thorough observing and collecting in the Galipagos is clearly indicated by the data presented below.

Water economy of the white-crowned sparrow fZonotrichia leucophrys gambelii and, its use of saline water

Abstract: range are the arid portions of southern California and adjacent regions (Grinnell and Miller, 1944). It is one of the most conspicuous winter-visitant sparrows in Joshua Tree National Monument, located in the transition between the Mojave Desert and the Colorado Desert in California (Miller and Stebbins, 1964). In addition Banks (1963) reports the occurrence of large flocks of White-crowned Sparrows (not subspecifically designated) on several of the desert islands in the Gulf of California during March and April 1962. The physiology of photoperiodically influenced phenomena in the White-crowned Sparrow has been intensively investigated by Farner and his colleagues (for example, Farner, 1964); King (1964) has recently reported on its metabolism and body temperature, and Morton (1965) has analyzed its food intake and feeding periodicity. In spite of these many investigations and in spite of its frequent habitation of xeric situations in the winter, information on the water relations of the Whitecrowned Sparrow is fragmentary. This investigation undertakes to examine the water economy of the Whitecrowned Sparrow in order to expand our knowledge of its general biology. Specifically, the study attempts to assess the ability of the White-crowned Sparrow to maintain water balance on the desert and to utilize saline water that may be present in desert springs and as sea water in portions of its winter range.

Breeding of the Starling in Central Arizona

Abstract: The Starling (Sturnus vulgaris) has become established since 1954 as a common breeding resident in the Phoenix area of central Arizona (Monson and Phillips, A checklist of the birds of Arizona, 1964). This is not surprising in view of the character of the habitat available. Phoenix and several smaller cities lie in the Salt River Valley, a large, irrigated farming district. The Salt River Project, which serves a major portion of the Valley, provides water for 238,000 acres, including 160,000 acres under cultivation and 50,000 acres classed as residential. Cotton, alfalfa, grains, grapes, lettuce, and citrus are important crops. Starlings forage in fields and on lawns, and feed on cultivated fruits. In fall and early winter, flocks feed and loaf in large cattle feedyards. Good roosting sites are available in small cattail (Typha spp.) marshes. Taller oleander (Nerium oleander) hedgerows, old, untrimmed citrus groves, mesquite (Prosopis juliflora) thickets, and fields of tall, dense forage sorghum (Sorghum sp.) also serve as seasonal Starling roosts. An abundance of trees suitable for nesting is, however, the factor most directly accountable for the large breeding population. Descriptions of nesting sites and breeding habits presented in this paper are based on observations made from 1961 to 1964 in the Salt River Valley. From 1962 to 1964 I used boxes of the Ithaca design (Kessel, Amer. Midl. Nat., 58:257-331, 1957) to obtain information on the reproduction of the Starling in Arizona and to establish a banded population of known age. Dates of laying, clutch and brood sizes, and egg and nestling losses were the principal data recorded. On 14 February 1961, 50 boxes were placed on trunks of Washingtonia palms (Washingtonia filifera) along a one-mile sector of Litchfield Road in a cropland area two miles south of Litchfield Park. The elevation is 1030 feet. At Mesa, 28 miles east of Litch'field Park and 1225-feet elevation, 50 boxes were placed on shade trees and poles within a semirural area of approximately one square mile, which includes the 160-acre University of Arizona Experiment Farm. The boxes at Mesa were put up between mid-December 1961 and 20 February 1962, and were taken down in July 1962. On 11 March of the following season only seven boxes were set up on the Mesa study area while 90 boxes were used along Litchfield Road because these could be more easily inspected. All boxes were placed on the palm trunks on 14 and 15 February along a 1.5-mile sector that included the 1962 one-mile study area. In 1964, 10 boxes were placed along Litchfield Road on 2 January, and 11 boxes were used at the Mesa Experiment Farm. Six of the latter remained from the previous season and five were added on 5 February. I removed the Litchfield Park boxes on 27 April when the outcome of all first broods was known.

Abundance and Activity of Starlings in Winter in Northern Utah

Abstract: Starlings (Sturnus vulgaris) were first observed in Utah in the winter of 1939 (Lockerbie, 1939). It was 10 years before they reached sufficient numbers to become a nuisance to feedlot operators and fruit growers. During the 1950's Starlings in Utah increased tremendously. By 1960 feedlot operators in 16 counties were complaining of damage during winter feeding operations, and in Washington County in the southern part of the state the County Agricultural Agent reported that Starlings were the major agricultural problem. Starlings in Utah are now concentrating in winter flocks estimated to be as large as 100,000, and complaints of damage are increasing. Starlings will probably continue to increase in Utah during the 1960's, causing increased economic loss to the state's feedlot and orchard industry. Thus some control action appears justifiable. Previous studies of agricultural pests have demonstrated that effective control is not possible until the ecology of the species is known. Information regarding distribution, abundance, and movements during winter would indicate whether a stable winter population or a mobile, nomadic population is responsible for the loss to ranchers. The study area was near Tremonton, Box Elder County, northern Utah. The area is at 4500-feet altitude and is flat except for the meandering Bear and Malad rivers. The region is covered largely by grain and sugar beet fields. Many cattle feedlots and silage pits are scattered over the area, and flocks of sheep are present in some fields at certain times of the year. The climate is semiarid with cold winters and hot summers. Average annual precipitation is about 13 inches, and the annual mean temperature is 560F. Snow rarely remains on the ground for more than a few days after a storm. Spring is the wettest season of the year; nearly 40 per cent of the average annual precipitation falls in March, April, and May.

Fossil Owls from the Rexroad Fauna of the Upper Pliocene of Kansas

Abstract: Since 1936 field parties led by Claude W. Hibbard of The University of Michigan Museum of Paleontology have made extensive fossil collections from Upper Pliocene deposits in Meade County, Kansas, with the result that the Rexroad fauna from the Rexroad Formation, Early Blancan Age, is at present the largest known nonmarine Pliocene fauna in North America. Previous reports on some of the numerous bird remains found in this fauna have been made by Wetmore (1944), Tordoff (1951, 1959), and Collins (1964). Among the bird material yet to be described are 13 fossils which represent owls and which are the subject of this paper. The general paleoecology of the Rexroad fauna has been described by Hibbard (1941). The specimens herein described were collected at three localities: K.U. Locality no. 3, Fox Canyon Locality (UM-K1-47), and K.U. Locality 2a (Hibbard, 1950). The nomenclature of the bones used is that of Howard (1929), except where noted. Modern skeletons used for comparative material included representatives of all genera of owls occurring in the New World except Pseudoscops and Gymnoglaux and are mostly from the collections of The University of Michigan Museum of Zoology (UMMZ). Supplemental specimens were borrowed from the United States National Museum and the Museum of Vertebrate Zoology, Berkeley, California. The fossils are deposited in the collection of The University of Michigan Museum of Paleontology (UMMP).

Effects of Extended Tropical Photoperiod and Temperature on the Dickcissel

Abstract: The interplay between exogenous and endogenous factors in the regulation of the annual cycle of birds has received considerable discussion and experimental attention since the work of Rowan (see Marshall, 1961; Wolfson, 1960a). It has been argued that the annual cycle of tropical residents must be under predominantly endogenous control because of the constancy of their environment; but there are few instances reported for which such influence has been suggested to be primary (Chapin, 1954; Marshall and Roberts, 1959; Miller, 1959). With most tropical residents, environmental factors still operate to adjust the annual cycle so that the species breeds at the time most propitious for the survival of the young (Keast, 1959; Marshall and Disney, 1957; Skutch, 1950; Voous, 1950). It has also been suggested that temperate-zone breeders wintering in the tropics likewise must be under a high level of internal control, and that exogenous factors must operate primarily during the period of the year at higher latitudes, annually setting the cycles of internal physiological events (Curry-Lindahl, 1958; Marshall and Williams, 1959). Merkel (1963) compared the long-term effects of constant photoperiods on two species of passerines having different migratory ranges. He concluded that the gonadal and weight cycles are more internally established in the Whitethroat, Sylvia communis, which is an equatorial migrant, than in the Robin, Erithacus rubecula, which remains within the North Temperate Zone during its migration. These results again suggest that tropical-wintering species depend to a great extent on endogenous control of physiological events. The success of the Dickcissel, Spiza americana, which breeds in temperate North America and winters in the neotropics, is related to the photoperiod to which it is exposed during the breeding season. The longer photoperiods of the temperate summer result in the attainment of a positive energy balance of sufficient magnitude to facilitate successful breeding, even though the mean temperatures at these latitudes are a few degrees lower than those of its winter range during the same months (Zimmerman, 1965b). While still on the contranuptial area, Dickcissels initiate gonad recrudescence, accumulate depot fat, and captive birds show Zugunruhe. Although the photoperiodic control of these events has not been experimentally verified, it is probable that the developments of the reproductive and migratory states are partially dependent on light stimulation, as they are in temperate-zone (Dorst, 1955; Farner, 1964; Wolfson, 1963) and transequatorial migrants (Engels, 1959; Wolfson, 1963). To suggest that in the tropics these birds are unresponsive to the relatively constant daylengths is to disregard the conclusions of Wolfson (1952, 1960b) and Farner et al. (1953) on the nature of the effects of light. Through natural selection a species could adapt to the light periods that are experienced in its annual distributional pattern either by changes in the rate of response to stimulation (Wolfson, 1959a) or the inclusion of a refractory period of appropriate length (Marshall, 1960), or both. In order to ascertain the dependency of Dickcissels upon their natural photoperiod regime, birds were held for as long as 21 months under conditions of temperature and photoperiod that approximated those of their wintering grounds. This