Changes in numbers of calling males as a function of season and latitude.
In the northernmost part of its range, N. triops has one generation annually. Individuals mature before winter but delay calling, mating, and egg laying until the following spring. The black peak indicates that the entire population participates. From South Carolina to northern Florida, N. triops has a second, partial generation that calls, mates, and lays eggs in July and August (shaded peaks). Individuals that do not mature in time to reproduce in summer delay their reproduction until the following spring. Progeny of the summer generation that become adults in time to survive the winter join their aunts and uncles in the spring reproductive period (when all the population again participates). In south Florida (Palm Beach County), calling is nearly continuous, but the phrasing of the songs differentiates summer males and winter males. In the Florida Keys calling is heard every month and nearly all calls are summer songs, as is true throughout the Caribbean.
Figure based on Whitesell 1974 and Fulton 1951.