Song, mainly at dawn, a series of high-pitched chips alternating with a lower-pitched slow mellow trill; repertoire also includes a slow whistled phrase, a cascading call, and accelerating trills. Search Xeno-canto / Macaulay Library under 'Atlapetes nigrifrons' or 'Perija Brushfinch' (some archives file it under 'Yellow-breasted Brushfinch (nigrifrons)' / Atlapetes latinuchus nigrifrons).