On amplitude and frequency in birdsong: a reply to Zollinger et al.

► We reply to the criticisms of Zollinger et al. (2012, Animal Behaviour, 84, e1–e10).
► Properly used, frequency measurements on spectrograms have the advantage of resilience to noise.
► Using measurements of relative or absolute amplitude depends on the analyses intended.
► We reiterate the correctness of conclusions in Cardoso & Atwell (2011a, Animal Behaviour,82, 831–836).