Poor male strawberry poison frog (Oophaga pumilio). It worked hard to woo the females with loud - and probably tiring - ribbits, but turns out, all that effort mattered not one bit:
Researchers have found that despite the male's best efforts to impress, females simply mate with the closest frog to them. By choosing a neighbor, females minimize the risk of not mating at all, as receptive females abound and they have only a short time to fertilize their eggs. [...]
Females can simply choose the closest frog as, after their fighting, all victorious males with an established territory are of an acceptable standard to mate. Why go further afield, when the guy next door is just as good?
Link (Image: Ivonne Meuche)
Previously on Neatorama: 30 Strangest Animal Mating Habits