It goes down this way because, like most frat parties you can remember from college, the ratio is skewed. Sometimes males outnumber the larger females as much as 10,000 to 1. As Doug Collicutt, a biologist, told the New York Times: “Imagine trying to find a slightly bigger piece of spaghetti in a colander of spaghetti, and it’s moving.”
The female, swarmed with male suitors, eventually decides which one she will select (and may take several through an aptly named, not-terribly-clear process called "cryptic female choice"). After she and her chosen mate get busy, she can choose to either let his snake-semen-filled plug dissolve and mate with another, or go off on her own to carry the babies to term by the time August rolls around. Evolution, in this case, seems cannily progressive.