Green Treefrogs, which are most common in the southern United States, have been a subject of my research in animal sound communication for many years. As in most frogs, the male calls and the female moves to him to initiate mating. Although recording the calls of males and testing the selectivity of females for call variations with playbacks have been the main focus of my research, we discovered early on that calling males do not always get the female.
Earlier this month (June 2010) in southern Illinois, we were lucky to film such action, when a male that was not calling (a “satellite” male) managed to intercept a female heading toward toward a male who was calling. The caller was a bit slow and clumsy, giving the satellite male the opening he needed. Once mounted, the successfully mating satellite male produced raspy “aggressive calls” to discourage his rival. The loser (the calling male) nevertheless tried to join the party, but his efforts failed. You can observe all this exciting behavior in the second half of the following video:
In field experiments we conducted in 1978 (Science magazine, Vol. 200, pp. 1179-1180), we found that nearly 50% of the females approaching a calling male were intercepted by silent, “satellite” males that we had observed sitting close to calling males. The late Walter Sullivan, a famous science editor for the New York Times, likened the satellite male in these situations to Cyrano de Bergerac in Rostand’s play, who wrote poems for a suitor but remained silent himself.