Eumetopias jubata is highly polygynous, but cows are free to move where they choose on pupping colonies. Consequently, the spatial preferences of pre-estrous cows greatly influence the reproductive success of established territorial bulls. In this study, I have observed large numbers of individually recognizable cows on an undisturbed pupping colony to identify environmental and other factors that influence spatial preferences of pre-estrous cows. Results indicate that movements and distribution of pre-estrous cows primarily reflect tradeoffs between sites' accessibilities from the sea, protection from waves, and degrees of crowding. Cows without pups generally travel only far enough inland to find a vacant rest spot not splashed by waves. Cows with pups use rest spots that are farther inland and more protected from waves. Other significant influences in spatial preferences of pre-estrous cows are ruggedness of terrain, the tendency to "home", patterns of access on the colony, and availability of water for use in thermoregulation. Cows tend strongly to occupy level, flat areas away from precipices or deep clefts in the rock substrate of the colony. Some cows apparently are bred in transit by bulls who have territories that include highly preferred access routes. Cows tend to home to the same vicinity of the colony in successive years. Cows tend somewhat to frequent areas with ready access to water used in thermoregulation. I propose an evolutionary sequence in which the extreme concentration of breeding Otariids in space can be accounted for by positive feedback mechanisms in sexual selection that were first proposed by R. A. Fisher in 1929. / Science, Faculty of / Zoology, Department of / Graduate
| Identifer | oai:union.ndltd.org:UBC/oai:circle.library.ubc.ca:2429/20312 |
| Date | January 1977 |
| Creators | Edie, Allan George |
| Source Sets | University of British Columbia |
| Language | English |
| Detected Language | English |
| Type | Text, Thesis/Dissertation |
| Rights | For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use. |
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