As winter approaches its end in the midwest, there are three frogs that I think of as the harbingers of spring. These three frogs emerge as temperatures rise, sometimes hopping over snow and ice to reach their breeding sites. Occasionally, these three frogs occur together, breeding in the same wetlands. However, there are important differences in the ecological niches occupied by the tadpoles of these three frogs. Below are a few photos and videos to introduce these frogs.
Chorus frogs (Pseudacris triseriata) are small and brown, with a few stripes running longitudinally along the back. Their call is reminiscent of the sound of a finger running down a comb. Chorus frogs typically breed in highly ephemeral ponds that dry quickly. Their larvae are highly active foragers so that they can consume enough food to metamorphose out of the pond before it dries.
Spring peepers (Pseudacris crucifer) are another small frog, with background colors ranging from dark brown to very pale tan. Their distinguishing feature is a distinct cross pattern on their back. A high-pitched ‘peep’ is the sound of the males’ call. The sound emanating from large choruses of spring peepers is deafening. In contrast to the chorus frog, spring peepers tend to breed in less ephemeral wetlands with greater abundances of predatory insects and salamanders. Spring peeper tadpoles are less active, so they are less likely to be captured by a predator. However, they grow more slowly than chorus frogs, and thus cannot metamorphose as quickly in case of pond drying.
Wood frogs (Rana sylvatica) are several times larger than chorus frogs and spring peepers. Their body coloration is typically brown or tan, but occasional individuals are bright red. The males’ call is reminiscent of a quacking duck. During the breeding season males gather in large groups, bickering and fighting over female frogs. The video below shows a bit of these entertaining interactions. Two male wood frogs call back and forth at one another, briefly engage in a wrestling match, call again, and then the smaller one retreats. Wood frogs breed successfully in a range of fishless wetlands, from sunny swamps in open fields to small woodland ponds heavily shaded by the forest canopy.