Many species of songbirds appear to use received song to estimate the relative distance to singing conspecifics (ranging). Habitat-induced degradation offers relevant cues. Reverberations extend transmitted elements with a 'tail' of energy, which effectively fills inter-element pauses and can overlie successive elements. We use a transmission experiment to investigate this tail energy in wren Troglodytes troglodytes song. Our quantification uses a technique which results in a tail-to-signal ratio (TSR) and a measure of the rate of tail energy decline (RTD). Both measures vary with transmission distance; TSR increases whilst RTD decreases. We conclude that these kind of features of the tail energy could potentially operate as ranging cues. In addition, we quantify the decay of the undegraded elements. The element decay is markedly faster than the decline of the tail energy once the elements have been transmitted. We suggest that this could provide wrens with the opportunity to differentiate between non-transmitted sound (their own) and transmitted song. A strategy whereby energies are compared absolutely could be operative independently of familiarity with the specific song type received.
ranging, degradation, reverberations, wren, Troglodytes troglodytes