Tests on male goats were designed to determine their capacity for colour vision. The colours yellow, orange, blue, violet and green were tested against gray nuances of like brightness. Goats were found to be able to distinguish between colours and gray nuances. The rate of errors increased in the order: orange, green, red, yellow, violet, blue.
In an attempt to explain apparent differences in the pigeon homing behaviour over different regions, some experiments with anosmatic birds have been repeated on German birds. The poor initial orientation in either controls or experimentals in many single experiments and in pooled data was an insufficient basis for the evaluation of the influence of olfactory deprivation on homeward directedness. Homing success, however, was significantly worse in experimentals than in controls, which confirmed the result of impaired homing ability of anosmatic pigeons.
The significance of massed and distributed practice in discrimination learning to criterion by goldfish was studied. All animals were trained to discriminate between 6 horizontal black and white stripes (positive stimulus) and 2 vertical black and white stripes (negative stimulus). 5 groups of animals, 12 Ss each, got different training programs. Groups varied in number of trials per day (30, 10, 5 successive trials) and in distribution of trials over the day (30 trials given in blocks of 5 with ITI of 1 h or 5 trials, each spaced by an ITI of 1 h). In general animals with a small number of massed trials/day were superior in early acquisition period. When trials/day were spaced the method proved to be more efficient. The training method showed no effect concerning retention.
Homing behavior in salamanders (Salamandra salamandra) was studied in the field (52 adults) and in laboratory experiments (75 adult animals). Displacements, occluding of sense organs and experiments with different visual patterns revealed that the home-site orientation is guided by vision. While visual landmarks are most important, Salamandra is also able to use a moon-compass.
The influence of isolation on male-female relationships was investigated. Animals isolated between 90 and 200 days of age showed more agonistic behaviour in paired encounters than controls. This difference disappeared when the animals had been housed with a cagemate. A secondary isolation late in life resulted in a more rapid onset of agonistic behaviour in the early isolates than in the controls. Thus it is concluded that the early isolation had a lasting influence, which only became evident after renewed isolation treatment.
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