One spring six decades ago, in the ponds and marshes along a western arm of Lake Michigan, about 25 miles north of the city of Green Bay, Wis., the northern leopard frog Lithobates pipiens was busy breeding. The males trumpeted sex calls that vaguely sounded like, “ ’ere I am,” followed by croaks of “rah-rah-rah” when they sensed females nearby. The females responded with their own throaty grunts.
The outcome of this noisy annual ritual was a lot — an awful lot — of fertilized eggs attached to plants or afloat in the waters of the marshes. During a normal breeding season, the lake would recede and the water would dry up or grow shallow, allowing only about 1 percent of the spawn to survive and mature. A different scenario played out in 1952. The water of Green Bay, which normally floods in the spring, remained at a high level into the summer, and the wind kept whipping water into the adjoining marshes and ponds. Bayside roads crumbled from wetness, and shoreline homes became uninhabitable. But amphibians laid their eggs as usual.
