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Portland State University

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Articles 271 - 279 of 279

Full-Text Articles in Animal Sciences

A Behavioral Study Of A Small Group Of Pikas (Ochotona Princeps) On Mt. Hood, Oregon, Nancy A. Ewen Frazier May 1977

A Behavioral Study Of A Small Group Of Pikas (Ochotona Princeps) On Mt. Hood, Oregon, Nancy A. Ewen Frazier

Dissertations and Theses

Observations or a small group of pikas, (Ochotona princeps) occupying a southwest facing roadfill on Mt. Hood, Oregon (1518 m) were made during the fall or 1976. Territorial sizes of 305.5 m2 and 121 m2 were determined based on territorial displays. These territories were compared with those observed in other studies. The mean distance to the nearest neighbor was 15.1 m. A pair relationship between two of the pikas and a dominance order are discussed. The seasonal progression of the haypiles and the reactions of the pikas to other animals are also noted.


Behavioral Temperature Regulation In The Turtle Pseudemys Scripta Elegans, Michael H. Johnston May 1977

Behavioral Temperature Regulation In The Turtle Pseudemys Scripta Elegans, Michael H. Johnston

Dissertations and Theses

A group of red-eared turtles (Pseudemys scripta elegans) was acclimated to 18-20˚C and artificial photo-period for 21 days. The animals were then individually placed in a thermal gradient and their selected temperatures were continuously recorded for 24 hours. A second group of turtles was acclimatized to 7.5-11.0˚C and natural photoperiods for 28 days, and subsequently tested in the same manner as the first group. Lastly, the turtles in the first group, after being acclimated to 3.0˚C and the previous artificial photoperiod for 14 days, were retested in the gradient.


The Chromosome Constitutions Of A Hybrid Salmonid And Its Parental Types: Salmo Gairdneri And Salmo Clarki, Peter Bruce Valentine Jacky May 1976

The Chromosome Constitutions Of A Hybrid Salmonid And Its Parental Types: Salmo Gairdneri And Salmo Clarki, Peter Bruce Valentine Jacky

Dissertations and Theses

A study was undertaken to investigate the application of tissue culture and histochemical banding techniques normally used in mammalian studies to fish cells and to examine the mechanisms of chromosome evolution and speciation in salmonids by comparing the chromosomes of the hybrid to those of the parental types. The application of banding techniques was generally unsuccessful in revealing bands, though quinacrine staining did reveal the presence of two fluorescent spots in the vicinity of the centromere. These were thought to be heterochromatic blocks, possibly related to the high incidence of centric fusion or fission in salmonids. Results of chromosome analysis …


Eutamias Minimus And E. Amoenus: Morphological Cluster Analysis, Sandra Elaine Anderson Aug 1974

Eutamias Minimus And E. Amoenus: Morphological Cluster Analysis, Sandra Elaine Anderson

Dissertations and Theses

Cluster analysis of a large body of data on 180 Oregon specimens of Eutamias minimus and E. amoenus suggest that overall length of skull, basal length of skull and length of palate are taxonomically critical. If their sum is less than 71.3 millimeters the animal is E. minimus. If the sum is greater than 72.7 millimeters the animal is E. amoenus. If the sum is between 71.3 and 72.7 millimeters, other factors must be considered before the animal can be identified. Of the 180 specimens, there were 60 E. minimus, 114 E. amoenus, 2 hybrids, 2 …


Possible Avian Influences In The Distribution Of Dwarf Mistletoe, Paul James Zilka Jul 1973

Possible Avian Influences In The Distribution Of Dwarf Mistletoe, Paul James Zilka

Dissertations and Theses

The goal of this investigation was to determine the potential of birds as vectors for the movement of dwarf mistletoe seeds and the means by which such movement could occur. Birds would greatly speed the rate at which these parasites move horizontally or vertically through the forest. Five areas in Oregon, heavily infected by six species of Arceuthobium were studied. Observations of avian behavior point to 13 species whose general behavior make them potential vectors in the distribution of these parasites. More specifically, the roosting and subsequent bathing behavior of most forest birds proves a very important means of potential …


Factors Affecting The Population Of Raptorial Birds On Sauvie Island, Oregon, Jeffry Gottfried Dec 1972

Factors Affecting The Population Of Raptorial Birds On Sauvie Island, Oregon, Jeffry Gottfried

Dissertations and Theses

This study is an analysis of the various factors affecting the population of raptorial birds on Sauvie Island, Oregon. A census of diurnal and nocturnal raptors was carried out along with an analysis of food habits. Once the major prey species were determined they were censused, and the effects of the land management practices on their numbers was investigated. In addition, 100 randomly selected nest boxes were sampled so as to determine the extent to which raptors were making use of them. Red-tailed hawk and Great Horned Owl nests were located.

It was found that four diurnal raptors and three …


A Taxonomic Study Of Two Nominal Subspecies Of Pikas (Ochotona Princeps) In The Cascade Mountains Of Oregon, Richard M. Coots Jan 1972

A Taxonomic Study Of Two Nominal Subspecies Of Pikas (Ochotona Princeps) In The Cascade Mountains Of Oregon, Richard M. Coots

Dissertations and Theses

Pikas from four colonies in the Cascade Mountains of Oregon were examined. Two colonies were chosen from within the geographical distribution of two nominal subspecies. A discriminate analysis of morphological measurements taken from the specimens showed that each colony could be distinguished from each other. Each colony studied showed more intra-colony similarity than inter-colony similarity regardless of distance separating the colonies or subspecies designations. The results indicate that the validity of subspecies designations for this species can be questioned.


Behavioral Changes Due To Overpopulation In Mice, James Robert Hammock Jul 1971

Behavioral Changes Due To Overpopulation In Mice, James Robert Hammock

Dissertations and Theses

Previous research has found that if a population were allowed to exceed a comfortable density level, then many catastrophic events occurred such as increased mortality among the young, cannibalism, homosexuality, and lack of maternal functions. The most influential researcher in this area is Calhoun (1962), after whose experimental design a pilot study was fashioned to replicate his results. The results of this pilot study inspired a more detailed research project of which this thesis is an account.

Forty-eight albino mice of the Swiss Webster strain were divided into three groups of sixteen each. Each group consisted of ten females and …


Lactic Dehydrogenase Isozyme Isolation By Disc Electrophoresis In Eight Species Of Fringillid Birds, Michael Edwin Darling Jul 1970

Lactic Dehydrogenase Isozyme Isolation By Disc Electrophoresis In Eight Species Of Fringillid Birds, Michael Edwin Darling

Dissertations and Theses

Disc electrophoresis of tissue homogenates from eight species of fringillid birds showed five forms of lactic dehydrogenase. The relative amounts of isozymes were characteristic for each species. This paper classifies some members of the families Fringillidae and Carduelidae in terms of lactic dehydrogenase isozymes and compares the results to other methods of classification.