Localization of noise, use of binaural cues, and a description of the superior olivary complex in the smallest carnivore, the least weasel (Mustela nivalis).

Cats and dogs have relatively good sound-localization acuity, and the question arises as to whether this trait is a characteristic of all carnivores or whether it is due to the fact that they have large heads and correspondingly large binaural localization cues available to them. The localization acuity of the least weasel, the smallest extant carnivore, was found to be less accurate than larger carnivores but more accurate than other small mammals. This suggests that carnivores may be under strong selective pressure to localize accurately but that interaural distance may be a limiting factor. The least weasel is capable of using both binaural phase differences and intensity differences to localize, but has a relatively broad mid-frequency range for which neither cue is optimal. Finally, the superior olivary complex of the least weasel is well developed and resembles that of larger carnivores more than that of small rodents.