Aspects of reproduction in ruffed lemurs (Lemur variegatus).

Results of breeding of ruffed lemurs (Lemur variegatus) at the Duke Primate Facility provide information concerning estrous cycle, sexual behavior, age of first conception, gestation period, parturition, litter size. L. variegatus differs from other Lemur species in these respects.

The oestrous cycle of the brown lemur, Lemur fulvus.

Examination of vaginal smears and observations of the colour and tumescence of the genitalia and discharge of mucus of 9 brown lemurs indicated that the oestrous cycle lasted for 30 days and that cycles occurred between September and July. The timing of cycles of females housed in visual isolation differed from that of females able to see other lemurs, indicating that the oestrous cycle in this species can be influenced by different housing conditions.

The birth and early development of a captive sifaka, Propithecus verreauxi coquereli.

We report here our observations on parturition and infant development up to five months in a captive sifaka, Propithecus verreauxi coquereli. Comparisons are made with other reports of Propithecus. In describing the acquisition of developmental landmarks, a distinction is made between the first sighting of a behavior pattern and its regular occurrence in the infant's repertoire. We describe the development of locomotor abilities, grooming, feeding, play, and social interactions. In general, maturation of Propithecus is slow relative to species of the genus Lemur.

Isolation-induced aggression in newly hatched ducklings.

Newly hatched Khaki Campbell ducklings (Anas platyrhynchos domesticus) were initially housed in pairs and subsequently transferred to isolated housing conditions. Subjects living with another bird displayed filial behavior and little aggression upon encountering another duckling in a test arena. In contrast, ducklings housed in isolation exhibited aggressive pecking in addition to filial behavior when another duckling was subsequently encountered. In Experiment 2, ducklings were housed with an imprinting object (i.e., an object that elicits attachment behavior), but they were otherwise isolated from other birds. These subjects displayed little aggression when they were subsequently reunited with a conspecific, indicating that the aggression-precluding effects of social housing are not limited to the particular social stimulus with which the ducklings are housed. In Experiment 3, ducklings were again housed with an imprinting object, but this time the object was behind glass, thereby precluding tactile contact with it. Since these birds also exhibited little aggression when reunited with a conspecific, it is apparent that visual stimulation from an imprinting object is sufficient in itself to preclude subsequent aggression. These findings suggest that stimulation that elicits attachment behavior is the critical factor mediating isolation-induced aggression.