Thursday, February 20, 2014

More On The Promiscuity Among Bighorn Sheep: Or, While The Big Boys Fight it Out, I will Take My Chances!

by Steve Reiss (Dalmdad Landscape Photography - and

More on the subject of promiscuity among bighorn sheep.

Bighorn sheep are promiscuous rather than polygamous, in their breeding habits, the rams being indiscriminate in their selection of a mate and the ewes accepting copulation by more than one male.  According to one researcher, "Most, and perhaps all, ewes are bread many times during the receptive period, not only by different rams, but quite often several times by the same ram within a very few minutes."  Acceptance in copulation of several different rams was witnessed as two different rams copulated with the same ewe within the space of seconds.

During breeding activity there is much chasing of ewes by rams.  One researcher noticed that chases starting with 1 ewe and 1 ram often ended with as many as 11 rams in pursuit.

In one herd (harem), each of two rams was observed to copulate with the same ewe in the course of 20 minutes.

In another siting, 6 mature rams attempted to breed one ewe.  The ewe accepted at least three different rams in copulation several times.

On another occasion, 3 rams attempted mating with 1 ewe.  Two rams, were large, mature animals of about the same size, whereas one was much younger.  While the ewe was receiving much attention from the older rams, the younger individual did not approach more than 50 feet from the group.  Each of the older rams made repeated attempts to mount the ewe, only to have the other ram interfere.  On two occasions, both rams attempted to mount the ewe at the same time, the last of which terminated in vigorous battles taking place over 20 minutes.  Meanwhile, the fighting of the two larger rams allowed the younger ram to successfully copulate with the ewe.
One ram can serve perhaps 10 to 20 ewes.
From The Bighorn Sheep in the United States by Helmut Buechner (1960).

"Where can I find a good time around here?"

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