An estrous female calling with a series of distinctive long (~5-6 seconds), highly modulated, rolling rumbles that she repeats at intervals, as if in song. Her calling begins immediately her mate dismounts. Each Estrous-Rumble starts at relatively low frequency, rises sharply and descend slowly, and calls may be repeated for up to 45 minutes. We refer to these calls as Estrous-Rumbles and this pattern of calling as an Estrous-Song.
