Eight Experimentally Naive Homing Pigeons (Columba Livia), Obtained from Double T Farm

Method

Subjects

Eight experimentally naive homing pigeons (Columba livia), obtained from Double T Farm (Glenwood, Iowa), served as experimental subjects. Supplementary mixed grain was provided after daily sessions as necessary to maintain 85% of their free feeding body weights. The pigeons were housed individually in standard cages with free access to water and grit under natural lighting conditions in an environmentally controlled animal facility.

Apparatus

Four pigeon chambers were used. Two chambers were standard BRS-140 pigeon chambers (24 cm wide, 35.5 cm long, and 29.5 cm high). The front panel was equipped with three 2.5-cm response keys (Med Associates ENV-123 with tri-color displays) arranged horizontally. Each key could be illuminated white, red, or green and was located 22 cm above the floor. A force of approximately 0.15 N was necessary to operate each key. A food hopper (BRS/LVE grain magazine) centered below the center key 7.5 cm from the floor, provided access to whole wheat grain. The magazine was illuminated when food was presented. Each experimental chamber was enclosed in a sound-attenuating box equipped with a 7-W 120-V nightlight, located on the upper back wall of the box (behind the operant chamber), and a fan that provided air circulation and masked extraneous noise.

The other two chambers were Gerbrands-style pigeon chambers (35 cm wide, 43 cm long, and 36 cm high) were equipped with three 2.5 cm response keys (Med Associates ENV-124 with multicolored displays) in a row 23 cm above the floor. Each key required a force of approximately 0.15 N to operate. A food magazine (Lehigh Valley Electronics) was centered below the center key 7.5 cm from the floor, and the magazine was illuminated when food was presented. A 28-V house light (GE-1819) was located 6.5 cm above the center key. Ventilation fans masked extraneous noises. All chambers contained a miniature color television camera located at the top of the back wall of the chamber to monitor subjects from an adjacent room.

All operant chambers were controlled by a personal computer programmed in MED-PC IV with MED Associates interfaces, which controlled all experimental conditions and recorded every event and its time of occurrence with 10-ms resolution.