Sound production in the pygmy sculpin Cottus paulus (Cottidae) during courtship and agonistic behaviours.

A field study examined sound production in the pygmy sculpin Cottus paulus, a threatened species found only in Coldwater Spring (Coosa River drainage), Alabama where the study was conducted. Two distinct call types are made during both courtship and agonistic encounters: a single knock and a knock train. The duration of the knock train significantly differs between contexts, while the signal structure stays the same. Knock trains are longer when the intended audience is a female, while short and abrupt when intended for a male intruder.