Zugl.: Berlin, Freie Universiẗat, Diss., 2007. / Includes bibliographical references.

Tierärztl. Hochsch., Diss., 2004--Hannover.

No description available.

Squirrels appear to be unique among sub-primate mammals in being able to see at least some colors. A readily available Oregon squirrel species, golden mantled ground squirrels (Citellus lateralis), which has not previously been tested under laboratory conditions for color vision, was subjected to color discrimination testing in a Skinner box. On the basis of recent physiological tests of color reception capacity and behavioral tests of color discrimination response in closely related species, it was predicted that this species should be able to discriminate blue, green and possibly yellow, but not red. Three experiments were conducted. The first, a pilot study, checked for discrimination of blue from green and blue from gray; subjects were rewarded for pressing on one color, shocked for pressing on the other color. The second experiment, the main part of the study, used one subject tor each of three discriminations: green from gray, yellow from gray, and red from gray. Here, a choice approach was employed: two bars were used, with subjects having to choose the correct one tor each stimulus, receiving a food reward for correct choices and no reward for incorrect choices. Third, a series of tests was devised to check for use of cues other than color as a possible basis for discrimination in the main experiment. These squirrels succeeded in discriminating all four colors, and results of the series of cue tests indicate they were not making significant use of non-color cues. Despite past results, therefore, it was concluded that this species is capable of seeing all colors in the visible spectrum. This result should be of interest to evolutionary theorists and may have important implications for current theories of color vision processes.

No description available.

The objectives of this study were to test for the feasibility of satellite radio-tracking of golden eagles (Aquila chrysaetos) breeding in the Grande-Baleine hydro-electric study area, to assess the size of their home-ranges, to determine their food habits during the nesting season, and to describe migration routes and wintering grounds of these birds. / In June and August 1992, six golden eagles, of which 5 adults (4$ rm sp{o}$ + 1 sex unknown), were caught and fixed with transmitters in order to follow their movements over one year. / The golden eagles fed on various animal species, i.e. 8 mammals, 15 birds and one fish, during the breeding season, however Canada geese (Branta canadensis) were the main item in their diet. / Four of the adult eagles undertook their fall migration in October 1992. The other adult eagle died of an unknown cause while the fate of the nestling could not be determined. All the migratory birds moved south to the United States, but they used different migration routes. The four golden eagles reached their wintering grounds in November and December, 1992. / After a three to four month stay in the wintering area, three eagles undertook their spring migration in March 1993. When returning to the breeding area, two of the eagles followed the same migration routes used in fall, while the third one flew off course to the west into Ontario. The first two birds reached their former territories in March and April while the third eagle only arrived in mid-May 1993.

Dissertation (PhD)--University of Stellenbosch, 2008. / Bibliography. Also available via the Internet.

No description available.

published_or_final_version / Anatomy / Doctoral / Doctor of Philosophy

No description available.