Abstract: Abstract and Summary: Since the adaptive significance of social organization is emphasized diversely in both anti-predator behaviour and food searching of birds, measures and comparisons of observational learning capacity of various species are needed. Four different experimental situations were built up for juvenile and adult individuals of tits (Parus major, P. caeruleus, P. palustris) and thrushes (Turdus merula, T. philo-melos). The birds learn more easily from conspecifics and learn easily when they already know a previous problem solving situation. The capacity of observational learning of the adult great tits surpasses that of adult blue tits and marsh tits, and that of the adult blackbirds exceeds that of the adult songthrushes. The higher performance of the great tit and blackbird can be related to their greater hemispheric index. The differences in the learning capacity of the naive individuals of the three tit species and that of the two thrush species were not significant. It is suggested, that the higher observational learning of the great tit and blackbird is evolved through maturational processes and can be reflected by their greater adaptability. Zusammenfassung: Lernen durch Nachahmung wurde in vier verschiedenen Situationen mit jungen und alten Individuen von Meisen- (Parus major, P. caeruleus, P. palustris) und Drosselarten (Turdus merula, T. philomelos) untersucht. Die Vögel lernten besser von Artgenossen und lernten leicht, wenn sie vorher bereits eine Problemlösungssituation kannten. Die Lernfähigkeit (durch Nachahmung) alter Kohlmeisen übertraf die alter Blau- und Sumpfmeisen; die Lernfähigkeit alter Amseln übertraf die alter Singdrosseln. Die höhere Leistung der Kohlmeisen und Amseln hängt mit ihrem höheren Hemisphären-Index zusammen. Naive Individuen der Meisen- und Drosselarten zeigten keine signifikanten Unterschiede in ihrer Lernfähigkeit. Es ist anzunehmen, daß die höhere Lernfähigkeit der Kohlmeise und der Amsel im Laufe der Entwicklung durch Reifungsprozesse zustande kommt und sich in ihrer höheren Anpassungsfähig-keit widerspiegelt.

Abstract: The feeding and drinking behavior of 11 mares and 15 foals living on pasture with free access to water was recorded during 2,340 15-min focal samples taken over 2 yr. Lactating mares on pasture spent about 70% of the day feeding. Foals began feeding on their first day of life. As they grew older, they spent progressively more time feeding, but still spent only 47 +/- 6% of the time feeding by 21 wk of age. Foals fed primarily during the early morning and evening. While grass formed the major proportion of the diet of both foals and mares, they also ate clay, humus, feces, bark, leaves and twigs. Almost all feeding by foals was done while their mothers were feeding. Movement to water sources was frequently, but not invariably, carried out by an entire herd. Frequency (P = .005) but not duration (P greater than .05) of drinking bouts by mares increased as the temperature increased. Frequency was greatest at 30 to 35 C, at which temperature mares drank once every 1.8 h. Frequency of drinking varied with the time of day (P less than .01), being rarest during the early morning (0500 to 0900 h eastern daylight time) and most frequent during the afternoon (1300 to 1700 h). Drinking by foals was very rare. The youngest age at which a foal was observed to drink was 3 wk, and 8 of 15 foals were never observed to drink before weaning.