Abstract: During locomotion, mammals update their position with respect to a fixed point of reference, such as their point of departure, by processing inertial cues, proprioceptive feedback and stored motor commands generated during locomotion. This so-called path integration system (dead reckoning) allows the animal to return to its home, or to a familiar feeding place, even when external cues are absent or novel. However, without the use of external cues, the path integration process leads to rapid accumulation of errors involving both the direction and distance of the goal. Therefore, even nocturnal species such as hamsters and mice rely more on previously learned visual references than on the path integration system when the two types of information are in conflict. Recent studies investigate the extent to which path integration and familiar visual cues cooperate to optimize the navigational performance.

Abstract: Fourteen riding horses of mixed age and breed were randomly allocated to observer and control treatments. An additional horse was pre-trained as a demonstrator to walk the 13.8 m length of the test arena and select one of two food buckets using colour and pattern cues. Observer horses were exposed to correct performances of the task by the trained demonstrator, for 20 trials held over 2 days. Control horses were subjected to the same handling and placement procedures as the observer horses but without exposure to the behaviour of the demonstrator. The third day for all subjects was designated as a test day. Each subject was released individually in a predetermined place in the arena, and the latency to walk the length of the test arena to the food buckets, the latency to feed, the identity of the bucket approached and the identity of the bucket selected were recorded on ten consecutive trials. During tests both food buckets contained food to minimize the possibility of individual trial and error learning. On the first trial the mean latency to approach the goal area was 18 s for observer horses, compared with 119 s for control horses (t = 2.8, d.f. = 12, P < 0.01) and the mean latency to eat was 35 s for observer horses, compared with 181 s for control horses (t = 4.86, d.f. = 11, P < 0.001). However, observer horses were no more likely to choose the demonstrated bucket than control horses on the first trial. Twelve of the 14 horses decreased their latency to approach the goal area during the series of ten trials, but there were no significant changes in the buckets selected.

Abstract: Over a 16-year period (1979-1994), long-term investigations were carried out on 14 Misaki feral stallions to analyze changes in harem size and the reproductive success. Harem size changed with the age of the stallions. Most stallions formed harem groups with four to five mares at the age of 4-6 and then the number of mares increased rapidly to the maximum at the age of 6-9 years. Thereafter, harem size decreased gradually to a minimum with advancing age. The harem size of 60 stable harem groups ranged from 1 to 9, and the average varied from a minimum mean of 1.8 in 1988 to a maximum mean of 5.3 in 1982. Mean harem size increased as adult sex ratio increased and a significant and positive correlation was found between them. One hundred and ninety-eight sire-foal pairs were determined by a paternity test with blood types and consort relations between stallions and mares during the study period. Out of 99 foals which were born in the stable harem groups, the true sires of 84 foals (85%) were the harem stallions in which the foals were born but the remaining 15 foals (15%) were sired by other harem stallions. Two out of three stallions which were studied throughout their lifetime produced 24 and 25 foals in 10 and 11 years of their reproductive lifespan, respectively. Another one produced only five foals in 6 years. The number of foals sired by the harem stallions was less than two over harem size 7 and some of the foals born in the harem were sired by other harem stallions. These results suggest that if a particular stallion monopolizes too many mares, he could not sire so many offspring because he could not always prevent his rival stallions from mating with his mares in wild or feral circumstances.

Abstract: Maternal affiliative relations may be transmitted to offspring, similar to the way in which maternal rank determines offspring rank. The development of 23 captive female rhesus monkeys (Macaca mulatta) was followed from the day of birth until adulthood. A multivariate analysis compared relations among age peers with affiliative relations, kinship, and rank distance among mothers. Maternal relations were an excellent predictor of affiliative relations among daughters, explaining up to 64% of the variance. Much of this predictability was due to the effect of kinship. However, after this variable had been controlled, significant predictability persisted. For relations of female subjects with male peers, on the other hand, maternal relations had no significant predictive value beyond the effect of kinship. One possible explanation of these results is that young rhesus females copy maternal social preferences through a process of cultural learning.

Abstract: Learning and memory abilities of 1-3 year old horses were assessed using instrumental and spatial tasks. No important differences were observed in the success of learning of the instrumental task (chest opening) according to sex or age. Younger females, however, seemed to learn more quickly. The offspring of a particular stallion were slower to learn than other horses. All horses memorised this task and opened the chest in a very short time in the second session. The animals that learned the task easily were not necessarily faster in the memorisation test. In the spatial task, learning ability did not seem to be related to age but more females than males were successful. The offspring of one stallion were more successful than other horses. Only 76% of the horses succeeded in the memorisation test, independently of age or sex. No correlation was found between the tasks in the latencies of either the learning or the memorisation tests for the same horses. The instrumental and spatial tasks may involve different processes.