Distance perception by non-territorial zebra finches (Taeniopygia guttata) and budgerigars (Melopsittacus undulatus).

Birds use long-range acoustic signals to defend territories, attract mates, and locate conspecifics. However, long-range acoustic signals progressively degrade during their transmission from the signaler to the receiver. This degradation makes perceiving these signals more difficult, but receivers can use such information to estimate the signaler’s distance. The perception of auditory distance cues (overall amplitude, frequency-dependent attenuation, and reverberation) has typically been studied in the field with territorial birds. The present study examined auditory distance perception in a non-territorial songbird, the zebra finch, and in a non-songbird, the budgerigar in a controlled laboratory setting. Three zebra finches and three budgerigars were trained to identify 1-m (undegraded) and 75-m (degraded) recordings of three budgerigar contact calls, one male zebra finch song, and one female zebra finch call. Test stimuli were then introduced on 20% of the total number of trials. These stimuli were created manually by manipulating the naturally recorded 1-m calls. By editing these calls, we could manipulate each distance cue separately to determine which cue was the most salient for the birds. Our results suggest that amplitude was the most important cue for these birds, similar to humans and other animals.