D. F. Holleman

Flow of digesta in the intestine and caecum of the rock ptarmigan

The role of the cecum in digestion of foodstuffs and production of vitamins is not well known for ptarmigan and grouse species. Presumably the function of the avian cecum is to digest and ferment complex carbohydrate molecules, proteins and other nutrients that escape intestinal absorption. The extent of fermentation in the cecum is a product of forage quality, cecum size and mean residence time of dry matter (DM), therefore mechanisms controlling filling and emptying of the cecum determine the kinetics and

Digestion of Dry Matter and Absorption of Water in the Intestine and Cecum of Rock Ptarmigan

Despite the many investigations of functional aspects of the hindgut in avian species (Sturkie 1965, Hill 1971, Hudson et al. 1971, Jayne-Williams and Fuller 1971, Ziswiler and Farner 1972), information about digestive function is still incomplete. The primary functions of the hindgut appear to be microbial digestion of carbohydrate and protein, absorption of end products of fermentation, water, some minerals, and microbial synthesis of vitamins. The cecum of all vertebrate

Estimating Populations of Marine River Otters in Prince William Sound, Alaska, Using Radiotracer Implants

One year after the spillage of oil from the Exxon Valdez in spring 1989, we used radiotransmitters and radiotracer labels to mark river otters ( Lutra canadensis ) at Knight Island (oiled) and Esther Passage (unoiled) in Prince William Sound, Alaska. Feces recovered from latrines of animals were used as “recaptures” in mark-recapture experiments to estimate the density of river otters in the two coastal study areas. Our methods were evaluated for sources of bias in estimating and comparing population sizes. There was no evidence that densities of river otters at Knight Island (oiled) were less than those at Esther Passage (unoiled) in summer 1990 or that density of river otters at Knight Island was declining. Estimates of river otters in Prince William Sound ranged from 0.28 to 0.80 animals per km of coastline. Our estimates are similar to those for marine river otters in southeastern Alaska, but bias in the different methods should be considered.

Modelling of radiocesium transfer in the lichen-reindeer/caribou-wolf food chain

The environmental contaminate radiocesium (cesium-137) has been shown to be of value as a marker in food selection and intake studies. Its greatest potential value as a food marker is in the subarctic/arctic regions, particularly in the lichen to reindeer/caribou to wolf food chain. A kinetic model describing the movement of radiocesium through the food chain has been developed using the SAAM computer program and is presented here. The program has been written so that the various paramenters affecting the transfer of radiocesium in the food chain can be altered more realistically to describe the system being modeled. The values of the parameters as given in this example are realistic for interior Alaska, however caution should be exercised in the application of the present results to regions that may be vastly different from the Alaskan interior without first evaluating the parameters and assumptions of the model.