The evening light is lingering over a small muskeg pond set in the scrubby shore pines of Southeast Alaska. It's early May, the days are getting longer and the snow has finally melted. The first mosquitoes are coming out, but otherwise all seems still. But there's activity in the pond - ripples and splashes in the vegetation under the water, and an unusual chirping call. Two eyes appear at the surface, and the wide mouth of a western toad. The short, frantic breeding season for western toads is underway.
Different species of frogs and toads tend to breed at the same time each year, but the exact time varies depending on weather. Western toads - and Alaska's other relatively common amphibian, the wood frog - breed early. They are explosive breeders, meaning they gather in large numbers for just a few days. Prolonged breeders, such as treefrogs and bullfrogs, which are not found in Alaska, will breed over a period of several weeks or longer.
Mating tactics vary depending on whether the species are explosive or prolonged breeders. For prolonged breeders, males establish territories and defend these prime calling sites from other males. Dominant males in prime sites attract more females. Satellite males, which are often smaller, quietly wait nearby to intercept an approaching female. In some species, satellite males may steal the perch of a dominant male that leaves to breed with a receptive female. Explosive breeders also claim prime sites, but males will temporarily abandon calling to swim after and grab frogs moving nearby in hopes of intercepting receptive females.