摘要
Abstract In many animal species, males direct more intense courtship towards females they have not previously encountered, than towards females with which they have previously mated. To test the factors responsible for this ＂Coolidge Effect＂, we need studies on a wide range of taxa - including those with mating systems in which we would not expect （based on current theory） that such an effect would be evident. The Coolidge Effect has been documented in several lizard species, but has not been looked for （and would not be expected） in snakes. We conducted experimental trials with red-sided garter snakes Thamnophis sirtalis parietalis at a communal den in Manitoba, to see whether previous exposure to a female （either courting, or courting plus mating） modified male mate choice or courtship intensity. In keeping with prediction from theory （but contrary to an early anecdotal report）, male garter snakes did not modify their courtship behaviour based upon their familiarity （or lack thereof） with a specific female. At least in large courting aggregations, male snakes may maximize their fitness by basing mate-choice upon immediate attributes of the female （body size, condition, mated status） and the intensity of competition （numbers and sizes of rival males） rather than information derived from previous sexual encounters .
基金
We thank A1 and Gerry Johnson for assistance, and the Manitoba Dept. of Natural Resources （especially Dave Roberts） for permits. Financial support was provided by the Australian Research Council and the Austra- lian Academy of Science （to RS）, and by the National Science Foundation （IBN-9357245） and the Whitehall Foundation （W95-04） to RTM. Research was conducted under the author- ity of Oregon State University Institutional Animal Care and Use Committee Protocol No. LAR-1848B. All research was conducted in accord with the US Public Health Service ＇Policy on Humane Care and Use of Laboratory Animals＇ and the National Institutes of Health ＇Guide to the Care and Use of Laboratory Animals＇.
