Dark Vertical Bars Research Articles

Voice and Social Behavior of the Chukar Partridge

The Chukar Partridge (Ale&& grueca) is difficult to study in the rugged country in which it occurs in the United States. Life history studies of the Chukar in Nevada (Christensen, 1954), Washington (Galbreath and Moreland, 1953), and Utah (Phelps, 1954) have dealt mostly with habitat and food requirements but only slightly with calls and social behavior. Hume and Marshall (1880), in what is the best description of the i bird in its native range, have little to say about calls or displays. Since so many calls of the Chukar are soft and infrequent, they are best studied under penned conditions. Goodwin’s study (1953) of the closely related Red-legged Partridge (Alectmis rufa) / : has been a great help. The white chin flanked by the black V, the conspicuous dark and white vertical bars on the flanks, and the chestnut tail feathers covered with gray upper tail coverts are conspicuous plumage characters prominent in the display of both species. Many of their calls are similar in quality and the situation in which they occur. Studies of the brown leghorn chicken by Wood-Gush (1954, 1956) have been especially valuable for their descriptions and analyses of galliform behavior. Wherever possible I have used the same terminology as the aforementioned authors in describing calls and behavior patterns. This paper presents observations on the behavior of the adult Chukar Partridge both in the wild and in captivity. This account is largely descriptive with only tentative conclusions about causation and function of behavior. For a quantitative analysis of the motivation of calls and display the reader is referred to a forthcoming paper “Agonistic and Sexual Behaviour in the Chukar Partridge” (Stokes, in press). This study was made from 1955 through 1960. In 19.55 I kept three males and five females in a pen with wire sides and top measuring 40X60 feet from January through May. The floor of this pen was bare ground during winter, but it had moderate ground cover in spring. In 1956 I used 12 males and 12 females. Three males and three females were kept in the same outdoor pen as in 1955 to observe display and pair formation. The remainder were separated as to sex and kept apart from the birds in the pen. From time to time these birds were placed singly in the pen to observe the reaction of the penned birds to newcomers. In 1957 I held 16 birds in three outdoor pens measuring 30x60 feet with emphasis on nesting behavior. In 1960 most observations were of birds kept in isolation except during paired encounters between birds of the same or opposite sex. These birds were exposed to 14 hours of artificial light daily from January 15 until then end of observation in May. Paired observations of these birds began in March at a time ’ when sexual and aggressive behavior was increasing rapidly. In addition to the caged birds, I observed Chukar Partridges in the wild in northern Utah for about 40 hours. I am indebted to the Utah Department of Fish and Game for the generous supply of birds from its game farm; to Dr. Carroll I. Draper, Department of Poultry Husbandry, and Dr. Arthur D. Smith, Department of Range Management, both at Utah State University, for the use of pens and other facilities; and to H. W. Williams and Dr. Keith L. Dixon for their critical reviews of the manuscript. This project was supported in part by the Division of Research and by the Utah Cooperative Wildlife Research Unit at Utah State University. CALLS

The Influence of Surround Brightness and Short Wave Components of Radiation on Dark Adaptation

Dark adaptation functions were determined by presenting a 2° square test field in the temporal parafovea, or a 1.3° field in the fovea, against backgrounds or surround luminances varying in brightness from complete darkness to 40 millilamberts. The test field was composed of parallel, equally spaced dark and light vertical bars, and presented in the form of flashes of 0.04 sec. As surround luminance is systematically increased the total extent of adaptation, the relative participation of rods and cones, and the transition from cone to rod function vary as a function of background luminance. Pre-exposure to a light source emitting radiation from 2850 to 4100 angstroms in addition to white light has an inhibitory effect on the sensitivity of the retinal receptors which is evident in higher excitation thresholds as compared with those obtained when the ultraviolet is screened from the pre-exposure source. The ultraviolet action which previously was only shown for the rods is also found in foveal and parafoveal cones, when, owing to the presence of a surround luminance, the rods are prevented from entering into action, and the range of adaptation is limited to levels above threshold for cone excitation.

Natural History Notes on Tiger Sharks, Galeocerdo tigrinus, Caught at Key West, Florida, with Emphasis on Food and Feeding Habits

T HE genus Galeocerdo belongs to the great family Carchariidae, the gray sharks. A number of species have been attributed to this genus, but the present tendency is to reduce these names to synonymy and make the genus monotypic-Galeocerdo arcticus. However, in this article the names used by the authors quoted will for convenience be retained. SIZE ATTAINED.-The tiger shark is one of the largest of the sharks that inhabit our coastal waters. It is said to attain a length of 20 to 30 feet. This may be true, but in this search no record of such giants has come to light. I cannot find anyone who has one as long as even 20 My own largest 11 ft., 6 in. Stewart Springer writes (personal communication) that in Florida waters he has measured many over 12 ft., one over 13 and none over 14 ft. He says that his fishermen friends have spoken of specimens over 16 and 18 feet long, but none of them had actually these giants. A specimen of G. tigrinus 15 ft., 2 in. long, reported by Burton (1941), was caught off the Charleston (South Carolina) jetties in 1940. This big male is the largest tiger shark known to have been captured in Western Atlantic or in Gulf-Caribbean waters. Beebe and Tee-Van (1941) say of the tiger shark in the eastern Tropical Pacific-Reaches a length of at least 20 ft. But the three largest specimens they were 10 ft., 1 in., weight 366 lbs.; 10 ft., 6 in., 505 lbs., and 12 ft., 9 in., 780 lbs. However, Whitley in his Fishes of AustraliaPart I, Sharks (1940), records as Galeocerdo rayneri an individual taken in 1936 at Maroubra, New South Wales, which 15 ft., 6 in. This is the largest tiger shark taken in any ocean, of which record has been found in this search. PHYSICAL CHARACTERS.-The tiger shark is well named-for its physical appearance and for its habits. It is a large, heavy shark, and its bluish-gray sides are marked with dark vertical bars or stripes like a tiger, as is faintly shown in Plate I. Sometimes the sides have short bars and these are often set staggered, whence probably comes the West Indian name leopard shark. From the figure it may be noted that Galeocerdo is very heavily built forward of dorsal fin I. It has a large bluntly rounded head, wider than deep, with wide heavy jaws having a large vertical gape. Both jaws are beset with many large, serrate, sickle-shaped or notched teeth-the hooks on the teeth all pointing outward right and left (Fig. 2). No explanation has been found for the peculiar shape of the teeth, but I suggest that they function with a shearing bite. These large jaws and saw-edged teeth are plainly adapted for chopping the prey into large fragments, which are swallowed whole. Of sharks whose teeth are known to me, only Carcharodon, the great white shark, has better chopping teeth. HABITS.-In its habits the tiger shark lives up to its name, being fearless,

AN UNUSUAL MASKINONGE FROM LITTLE VERMILION LAKE, ONTARIO

An unusual type of maskinonge found in two lakes in Kenora District, Ontario, is regarded as a hybrid between Esox masquinongy and Esox lucius. It differs from the typical maskinonge found in the same waters in having a stouter body, longer and deeper head, longer maxillary, and longer fins. It retains dark vertical bars throughout life whereas in the typical form these break up and tend to disappear with age. Of 69 specimens examined, six were of the presumed hybrid type. These all appeared to be sterile. They showed the following Esox lucius characters—cheeks totally scaled, head concave interorbitally, cheeks and opercula vividly marked.