Table 1.

Description of call parameter used in the analysis

Acoustic parameters	Description
Duration [ms]	Time between onset and offset of call
Amplitude gap [ms]	Duration of breaks in amplitude within call
PF start [Hz]	Start frequency of peak frequency
PF max [Hz]	Maximum peak frequency
PF jump [Hz]	Maximum difference of peak frequency between successive bins
PF max loc	Location of PF max in relation to total call duration (1/duration) * location]
PF jump loc	Location of maximum PF jump in relation to total call duration [(1/duration) * location]
Slope of trend	Factor of linear trend of peak frequency