Abstract: The purpose of this study was to develop an effective method for trailer loading horses based on principles of positive reinforcement. Target training and shaping were used to teach trailer-loading behavior to 5 quarter horse mares in a natural setting. All 5 had been trailer loaded before through the use of aversive stimulation. Successive approximations to loading and inappropriate behaviors were the dependent variables. After training a horse to approach a target, the target was moved to various locations inside the trailer. Horses started training on the left side of a two-horse trailer. After a horse was loading on the left side, she was moved to the right side, then to loading half on the right and half on the left. A limited-hold procedure and the presence of a companion horse seemed to facilitate training for 1 horse. Inappropriate behaviors fell to zero immediately after target training, and all the horses successfully completed the shaping sequence. Finally, these effects were observed to generalize to novel conditions (a different trainer and a different trailer).

Abstract: The mare is seasonally polyestrus, having an anovulatory period during the short light days of late fall and early winter, and beginning to ovulate as the days become longer during the winter. The complete estrus cycle is typically about 3 weeks, with 5 to 7 days of estrus and approximately 2 weeks of diestrus. When a mare lives within the natural social structure of the horse, i.e. a family band with several adult mares and one or more stallions, estrus is characterized by repeatedly approaching the stallion, frequent urination, deviating the tail away from the perineum, and standing still with the hind limbs spread apart. Diestrus is characterized by avoidance of an approaching stallion, and aggression toward the stallion, such as squealing, striking, and kicking, if he persists in attempting to court the diestrus mare. However, mares and stallions with long-term social relationships will often rest together, graze together and groom each other, all without sexual interactions. Hormonally, estrous behavior in the mare is initiated by estradiol that is secreted by the follicle, while estrous behavior is suppressed by progesterone, secreted by the corpus luteum. Mares are unusual among the ungulates in that they periodically exhibit estrous behavior during the anovulatory period. This is probably due to the release of estrogenic steroids secreted by the adrenal cortex. The display of sexual behavior by the mare throughout the year is thought to facilitate maintenance of the horse's social structure, in which the male remains with a group of females year round, in contrast with most ungulates in which the females and males only come together during the mating season.

Abstract: Dominance has been assumed to be a quality of overwhelming social importance but satisfactory definitions and measures have not been devised. As an indication of predictability of outcome of interaction between animals, it can be explained in terms of ordinary learning processes previous to and during a specific relationship. Agonistic interactions are usually determined and often initiated by the subordinate's behavior, and subordinate behavior is correlated with physiological changes, so that a subordination hierarchy is probably a more useful concept than a dominance hierarchy. Hierarchies develop in stressful conditions, especially in captivity where animals with overresponsive adrenal cortices are at a selective disadvantage. In wild groups hierarchies are tenuous or absent and stress-responsive members are probably advantageous to a group. Group defense and leadership roles are not correlated with rank, but policing is characteristic of high-ranking animals in species where it occurs. There is no evidence that formation of a hierarchy reduces aggression--hierarchies are actually associated with high rates of aggression in primate groups. There is no conclusive evidence that high ranking males have greater overall reproductive success, and an alternative hypothesis that adult males are sexually active for a relatively short stage of their lives fits existing data equally well.

Abstract: The three-dimensional structure of schools of saithe (Pollachius virens) and the interactions between individuals over time were analyzed in 12,240 frames of videotape sampled at 2.7 Hz. Time series analyses of the interactions between identified individuals allowed testing of assumptions of anonymity vs. leadership in schools and investigation of the transfer of information between individuals by which collective decisions are made. Results include the following:1.Saithe match changes in both swimming direction and speed of their neighbors but correlations are greater for swimming speed. Average speed of the school does not greatly affect correlations between neighboring fish although the reaction latencies may be somewhat increased. As shown previously (Partridge et al. 1980) nearest neighbor distance (NND) decreases with increasing school velocity.2.Saithe simultaneously match the headings and swimming speeds of at least their first two nearest neighbors within the school (NN1 and NN2). Partialling out the correlation between a fish's neighbors demonstrates that a fish's correlation to his second nearest neighbor (NN2) is not simply a transitive function of mutual correlation between the NN1 and NN2.3.Several sources of individual variation in schooling performance were examined. In all respects except one, that of preferred positions within the school, saithe showed no individual differences, i.e., some were not “better schoolers” than others. Although fish in the school differed in length by up to a factor of 2.5, no size related effects in NND or nearest neighbor positioning were found.4.Single Linkage Cluster Analysis (SLCA) of the cross-correlations of fishs' swimming speeds and directions demonstrated quantitatively the existence of subgroups within schools if they contain more than 10-11 members. Subgroups acting more-or-less independently in terms of short term variations in speed and direction nonetheless remained within the school as a whole and were not often apparent to observers since members of one group interdigitated with those of another. How individuals know to which subgroup they belong remains unanswered.

Abstract: One well-known solution to the iterated Prisoner's Dilemma is the TIT FOR TAT strategy. This strategy has three “characteristics” associated with it. TIT FOR TAT is nice (cooperates on the first move of a game), retaliatory (plays defect against an individual that defected on the prior move), and forgiving (cooperates with an individual which has defected in the past but cooperates in the present). Predator inspection behavior in guppies (Poecilia reticulata) was examined in order to determine whether guppies displayed these three characteristics. Results indicate that while it can be quite difficult to translate the abstract concepts of niceness, retaliation, and forgiveness into measurable behaviors, the data support the hypothesis that guppies display the three characteristics associated with the TIT FOR TAT strategy.