1. Three different groups of pigeons were given homing releases, the first at 143 miles and the other two at 75 miles. Approximately half of the birds (untrained group) had made no homing flight before they were released in the long-distance test. The others (trained group) had been released 3 times in different directions at 10 miles from the loft in one experiment and at 2-3 miles in the other two.
2. Both the trained and untrained birds showed a statistically significant tendency to vanish from sight at the release point in the homeward half of the circle, which confirms Matthews's results with untrained pigeons. There was no appreciable difference in homing success and speed between these two groups. More than 50% of each group homed, while Matthews had only one out of thirty-nine untrained birds return to the loft.
3. The untrained birds were released ahead of the trained birds in each experiment. In the third experiment, two untrained birds homed, separately, without being overtaken by any trained birds. Thus these two birds showed clearly that pigeons without previous homing experience could and would complete a long-distance flight to the loft unassisted. Subsequent tests in which only untrained birds were released have confirmed this finding.
4. Birds differing in both age and stock were compared in the second and third experiments. Within the range of 4-9 months, age was not found to be a factor in homing behaviour. Stock or the hereditary factor, however, was found to be related to success in regaining the loft, though it did not appear to influence the accuracy of orientation shown by the departure flights.
5. There is a suggestion that the height of the release point influences the immediacy of departure. Birds set free from the top of a 100 ft. tower vanished more quickly than pigeons released on the ground.
This research was supported by a grant of funds to the Parapsychology Laboratory from the Rockefeller Foundation.