Luke Nicol, “Chorusing Behavior of Eastern Gray Treefrogs”
Mentors: Gerlinde Hoebel and Kane Stratman, Biological Sciences
Poster #95

During the spring and summer breeding season, frogs of many species gather in and around suitable breeding ponds and form choruses where they call to advertise for mates. Males produce calls for many hours each night, often for many days or weeks. Females use these calls to find attractive mates, and initiate mating. Females of different species somewhat differ in which call characteristics they prefer, but males with high calling effort (long calls produce at high rate) are universally preferred. Yet, calling is one of the most energetic behaviors found in vertebrates and high calling effort should be unsustainable for long periods of time. We tested the hypothesis that here is a trade-off between short-term calling effort and long-term chorusing effort. This hypothesis makes the prediction that individual males that display extreme call effort (long and fast calls) will show reduced participation in the chorus (shorter/fewer bouts of chorusing). We tested this by continuously recording 28 male Eastern Gray Treefrogs (Hyla versicolor) for 60-90 min. We measured call duration (time from start to end of call) and call period (time from start of call to start of following) for every call given. Periods of calling separated by more than 30 seconds were considered different calling bouts. We calculated calling effort as (call duration / call period), and chorusing effort as (bout duration/recording duration). We found that chorusing effort is highly variable. Contrary to our prediction, there was no trade-off between calling effort and chorusing effort. The metric of calling effort (call duration and call period) does not generally predict the duration of nightly activity. However, high call rate males invest in very few, very long, bouts.