Wood Frogs are one of the earliest-breeding frogs within their geographic range. As winter turns to spring, and air temperatures begin to warm, adult wood frogs migrate to wetlands to breed. Wood Frog mating aggregations are raucous affairs in which males chuckle and wrestle with each other in their attempts to mate with females. These tightly-clumped breeding aggregations end up with the females laying their eggs in large groups.
Eggs from a wood frog breeding aggregation a day or so after breeding occurred. There are 714 eggs here! Counting egg masses is a good way to estimate amphibian population size. Since female wood frogs typically lay a single egg mass, this suggests about 714 female wood frogs bred here. There are typically more males than females, with sex ratios frequently higher than 2 males : 1 female. So probably more than 1,400 male wood frogs were in this pond. Also interesting to consider is how many eggs are in the pond. Each egg mass contains about 700 eggs. So about half a million wood frog eggs went into this pond! The larval period is particularly dangerous to amphibians like wood frogs, and it is likely that most of these little wood frogs will die from predation, disease, or desiccation before the tadpoles metamorphose into juvenile frogs.
The photo above shows a cluster of four egg clutches laid by wood frogs along a submerged branch. This is likely the result of four separate females laying eggs. A fifth egg mass can be seen on the right edge of the photo.
The photo above shows an underwater view of Wood Frog eggs. Many of the eggs are close to hatching, and a few of the eggs have already hatched.
All text and photographs © Michael F. Benard