Auditory sensitivity of the redwing Blackbird (Agelaius phoeniceus) and brown-headed cowbird (Molothrus ater)

Used 3 behavioral procedures to measure the auditory sensitivity of 10 redwing blackbirds and 6 brown-headed cowbirds. In the 1st procedure, a go-left/go-right task, an S initiated a trial by pecking a center key; a tone was presented with 50% probability on each trial. An S was rewarded with grain for pecking a right or left key, depending on whether a tone was present or not. In the 2nd, a go/no-go procedure, an S pecked the center key continuously until a 2-sec tone sounded; reinforcement then occurred if the S pecked the right-side key during the tone. In the 3rd, a modified go/no-go procedure, clearly audible tones were inserted into the regular go/no-go procedure whenever near-threshold tones were missed. All procedures produced similar thresholds for both redwings and cowbirds; hearing encompassed the range from 125 to 10 kHz, with lowest thresholds of 4-20 db sound-pressure level in the 2-4 kHz range. Two pigeon control Ss gave stable thresholds only under the modified go/no-go procedure. (23 ref) (PsycINFO Database Record (c) 2006 APA, all rights reserved).