The President and Mrs. Coolidge were being shown [separately] around an experimental government farm. When [Mrs. Coolidge] came to the chicken yard she noticed that a rooster was mating very frequently. She asked the attendant how often that happened and was told, “Dozens of times each day.” Mrs. Coolidge said, “Tell that to the President when he comes by.” Upon being told, the President asked, “Same hen every time?” The reply was, “Oh, no, Mr. President, a different hen every time.” President: “Tell that to Mrs. Coolidge.”
In biology, the Coolidge Effect was a term originally coined by Frank Beach to refer to the restoration of sexual activity among males that had previously reached sexual satiety when presented with a new female. More recently, that definition has tended to be broadened to encompass all forms of differential investment that males might exhibit towards novel females, and it is increasingly recognised that such investment can take on more cryptic forms. In a new paper together with Klaus Reinhold, Leif Engqvist and Albia Consul, we report one such example of strategic male investment, presenting evidence that male birch catkin bugs mate for longer with novel females.
Reinhold K, Engqvist L, Consul A, Ramm SA (2015) Male birch catkin bugs vary copula duration to invest more in matings with novel females. Animal Behaviour 109:161–166. doi:10.1016/j.anbehav.2015.08.020
Image credit: Calvin and Grace Coolidge, about 1918. Public domain image from Wikimedia Commons.