Why, why...
By sneaking off and secretly establishing a new territory with a new partner, the male flycatcher can father two sets of offspring. Why this devious game?
Who wins?
In this way, the male fathers more offspring and spreads his genes more widely among the next generation. He is the winner, producing about eight chicks per year instead of the five that are possible with only one mate.
Who loses?
The first female must share the male's chick-feeding capacity with the second female. Thus, she must work harder to feed the young.
Who loses most?
The big loser is the second female. Nearly half of all such females never get any help with feeding. They have on average only three chicks, which are often undernourished, and they are themselves exhausted.
