Digestive Tract Of Birds Research Articles

Avian Food Habits Analysis Using a Modified Counter

A counting device designed to enumerate samples of zooplankton was modified and used to count individual food items in samples from digestive tracts of waterfowl. This equipment permitted examination under magnification of an entire sample in one revolution of a wheel and reduced the time required to enumerate individual food items within a sample. COUNTER FOR FOOD HABITS ANALYSIS * Swanson and Thornsberry 949 slight modification to the template angle will be tested to try to overcome this anomaly, which must have been due to a difference in how effectively the charge was applied. The captive animals displayed no overt ill effects and continued to feed at their normal rate. No studies have been made of the subsequellt fate of the fine lead particles, from the fuse, which were injected into the skin. light modification to the emplate angle will The conventional procedure used to enumerate the contents of the digestive tracts of birds has generally been one of counting individual food items as they are moved from one location to another within the confines of a petri dish or similar container. This procedure is time-consuming and difficult to perform under magnification when samples are encountered that contain a large number of different food items. To improve this procedure, a counter previously designed for use in enumerating samples of zooplankton was modified. The counting device as originally described ( Ward l9SS ) contained accessory equipment that did not contribute significantly to its effectiveness but instead complicated its construction and may have discouraged its use. This paper describes a simplified version of the counting device that is easy to construct at a modest cost. DESCRIPTION AND USE The counting device consists of a grooved, transparent wheel ( No. 1, Fig. 1 ) mounted horizontally on a centrally located axle supported by a transparent table (No. 3). A translucent sheet (Nos. 6 and 8), located below the wheel on the table surface, diminishes the glare of light reflected into the wheel. This sheet also contains a stop line ( No. 7) to provide a stopping point in the event that a count is interrupted before being completed. A revolving mirror (No. 5), in the center of the table, directs light from an external source into the wheel groove when the supporting axle is rotated (No. 4). One or more dams (No. 2), located in the groove, stabilize the movements of items that are counted in a liquid medium. The dams also serve as reference points for initiating and terminating counts. Samples can be counted wet or dry deLITERATURE CITED CARRICK, R., AND SUSAN E. INGHAM. 1962. Studies on the southern elephant seal, Miroungs leonina ( L. ).

Long-distance dispersal of seeds by retention in digestive tract of birds.

Viable seeds of Celtis, Convolvulus, Malva, and Rhus were regurgitated from the digestive tract of kill-deer (Charadrius vociferus) after 160, 144, 152, and 340 hours, respectively; seeds were recovered in the same way, after long-time retention, from least sandpipers (Erolia minutilla). Most other birds do not retain seeds as long. There is evidence that seeds of many species can remain viable in the intestinal tract of some shorebirds long enough to be transported several thousand miles.

The Hair of California Mammals with Keys to the Dorsal Guard Hairs of California Mammals

It has long been recognized that hairs are as characteristic of mammals as are the glands which give the class its name. When hairs do not appear in the adult animal, as in Odontoceti, they are at least present in the embryo. They may be confined, as in Mysticeti, to the region of the nares, or they may appear over the entire body, as in the Reindeer, in which even the usually bare mammalian snout is hairy. In recognition of this characteristic presence of hair it was at one time proposed that the class should be named Trichozoa or Pilifera. In recent years significant investigations on hair have been few, the latest contribution of note being that of Hamilton et al. (1951). In the latter part of the nineteenth century and early part of the twentieth century more extensive research was accomplished. However, merely 47 of the more than 3000 references in the possession of the author deal primarily with hair as a means of classification or identification, and the majority of these are anthropological studies on human hair. Only 17 concern themselves wholly or in sizeable part with the problem of hair of mammals other than man. With respect, then, to its systematic usefulness little research on hair has been done, and the taxonomic value of hair is a subject on which all authors have not agreed. Cole (1924: 120) and Nason (1948: 358), studying bats, both came to the conclusion that hair is of little use- in identification. Mathiak (1938), Williams (1938), and Brown (1942) all arrived at the opposite conclusion, and prepared aids for identifying certain mammals on the basis of hair alone. With this latter group the present author is in complete agreement. The ability to make positive identification of mammalian hair is of great value in fields such as criminology and paleontology and particularly in the field of food habits studies. Fortunately hair is a relatively durable feature, and a high percentage of the shafts recovered from the digestive tracts of birds and mammals are capable of being used for the purpose of making identification. HAIR STRUCTURE The hair shaft is a highly keratinized column lacking both nerves and blood vessels. The follicle is formed embryologically as an ectodermal invagination of cells from the malpighian layer of the epidermis. This invagination splits, and cells proliferating from the ectodermal base of the follicle, and nourished by a deeper-lying dermal papilla, move peripherally as the hair shaft proper (Danforth, 1925: 23). As the hairs move outward from the basal.bulb, the cells become more highly keratinized and tend to lose their individual identity. 480

The Acanthocephalan Genus Corynosoma. I. The Species Found in Water Birds of North America

Individuals of the acanthocephalan genus Corynosoma reach sexual maturity in the digestive tract of birds and mammals, especially those in aquatic habitats or those feeding on fish or aquatic invertebrates which serve Corynosoma as intermediate hosts. Although the same species has often been reported from both aquatic birds and mammals, Lundstr6m (1941) has recently reviewed the evidences which seem to discount the possibility that both of these groups serve as normal to the same species of Corynosoma. In observations on the two best known representatives of the genus in Europe, Corynosoma strumosum and C. sermerme, Lundstr6m's results support those earlier announced by Forssell (1904, 1905). Both of these species are normal parasites in the intestine of fish-eating mammals, especially seals. Although both species likewise occur often in the intestine of water birds they never attain full functional maturity in these hosts. Larvae of these two species, in the bodies of fish, may be introduced into the digestive tract of birds that prey upon fish but the worms fail to prosper there sufficiently to bring their eggs to full maturity. Evidence of this sort constitutes one of the most valid indictments of the meaningless expansions of host lists which received so much attention on the part of parasitologists, particularly a generation ago. An analysis has been made of numerous collections of Corynosoma from various parts of North America. On this continent there are some species which normally parasitize birds and other species which infect mammals. There are no clearly marked evidences of infections occurring in the alternative group such as have been found for the European species. In the present paper, only those species which infect water birds of North America will be considered. One of these is a well known species, Corynosoma constrictum Van Cleave, 1918; the other is a new species here described as Corynosoma anatarium n. sp. Other taxonomic and morphological studies on Corynosoma are in the course of preparation for publication. In 1918, the writer described and named Corynosoma constrictum, the first valid species of the genus to be recorded from North American water birds. The material upon which the description was based had been collected by Dr. Edwin Linton from the intestine of the American scoter (Oidemia americana Swainson) on Yellowstone Lake in Wyoming. Dr. Linton (1892) had mistakenly identified the worms as Echinorhynchus striatus Goeze a species described from European water birds. The specific identity and generic assignment of this European species were long under discussion (Liihe, 1911) although Meyer (1931, 1932-3) more recently ascribed it to the genus Polymorphus. As pointed out by the present writer in 1918, the males of Linton's original specimens had conspicuous cuticular spines on the fore body (Fig. 10) and around the posterior extremity in the region of the genital pore. This last statement alone is proof of the fact that the individuals are of the genus Corynosoma. The genital spines were shown clearly in Linton's