To decipher the meaning of these vocal signals, he and his colleagues, Suzanne Page and Steve Glickman, presented adult hyenas with three objects: unfamiliar spotted hyena cubs, meaty bones, and the empty transport cage used to contain bones or cubs on other experiments. The cubs elicited more groans from more hyenas than other objects, and the groans elicited by other objects were less tonal in nature, with lower fundamental frequency. The researchers conclude that hyena groans can be classified into different groups, based on acoustic characteristics, and that the hyenas modulate the sounds they produce in response to different behavioral contexts.
However, the exact meaning of specific types of groans remains unclear. The groans directed to the cubs might be friendly if produced by a mother toward her cub, or it might be a warning signal for an unrelated cub. The number of recorded interactions is still too small to draw definitive conclusions. The UCB group would like to record the vocalizations of hyena cubs in future studies, to better establish the meaning of the communications.
Paper 4pABd1, "Vocalizations of the Spotted Hyena (Crocuta crocuta): Eliciting Acoustic Variation in Groans" will be presented at 5:20 p.m. on Thursday, July 3 in room 343.
4) CHINESE FROGS GO ULTRASONIC
Among vertebrates, only a few species are known to produce and detect ultrasonic frequencies for communication and for echolocation -- bats, dolphins and whales, and some rodents -- which suggests that this ability could be limited to mammals. However, UCLA's Peter Narins (firstname.lastname@example.org) and his colleagues recently uncovered the first evidence of ultrasonic communication in an amphibian: the concave-eared torrent frog (Amolops tormotus), found in Huangshan Hot Sprin
|Contact: Jason Bardi|
American Institute of Physics