SUMMARYSucking behaviour and age of weaning were investigated in a herd of East African zebu cattle in which all calves born had been retained for several years. Suckling rates were compared at different periods of the 24 h cycle and found to be less at night than during any day-time period. The highest rates of suckling took place in the early morning and in the late afternoon. The early morning suckling was triggered by the dawn. During both night and day, suckling was irregular and bouts were presumably due to sympathetic induction because a high proportion of the calves was suckled on each occasion. The total sucking time and the number of bouts varied significantly in inverse relation to age of the calf but the duration of a sucking bout was constant at 8 min and independent of age. There was an average of 4·8 sucking bouts within 24 h giving a total duration of 38 min. Sucking behaviour did not exhibit sex-specific differences. The average age of natural weaning was 10 months but there was a marked sex difference. Female calves were prevented by their mothers from sucking after an average age of 8·8 months but male calves continued to be suckled for a further 2·5 months and were weaned at an average age of 11·3 months.

Cohesive relationships were studied in a semi-wild cattle herd and traced over periods of three to five years. It became evident that mother cows prefer their female and male progeny over non-related calves as grooming and as grazing partners. These associations could always be verified during the first three years and often during the fourth and fifth year as well, the descendants already being sexually fully mature. Comparable personal attachments also existing between siblings, the ensuing family units were strikingly stable and cohesive. Interindividual associations lasting for several years could also be found between non-related descendants of the herd but also between non-related cows. The analytical data led to the conclusion that in natural cattle herds the social structure is based on matriarchal families which in their turn are interconnected by means of friendship relationships between non-kin partners.

Hair pulling and eating has not yet received attention in the nonhuman primate literature. Hair pulling and eating was recorded 388 times in two heterogeneous troops of healthy rhesus monkeys that were kept according to modern management practices. The behavior in question consists of the following sequence: (1) pulling with the fingers (1/3 of cases) or with the teeth (2/3 of cases) tufts of hair from one’s own or from a partner’s coat; (2) chewing the hair and finally swallowing it; the undigested material is excreted in the feces. Hair pulling was almost exclusively (378/388) partner-directed. It was observed 364 times between animals whose dominance relationships were known; it was performed in 96% (349/364) of observations by a dominant but only in 4% (15/364) of observations by a subordinate monkey. The recipient of hair pulling showed typical fear and/or avoidance reactions. In both troops young animals (2–8 years of age) engaged in hair pulling and eating significantly more often than old animals (10–26 years of age). There was no evidence that nutritional, toxicological or climatic factors were responsible for the manifestation of this behavior. It was concluded that, similar to trichotillomania in man, wool pulling and eating in sheep and muskox, and feather picking in poultry, hair pulling and eating is an aggressive behavioral disorder in rhesus monkeys reflecting adjustment problems to a stressful environment.

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