Although intraspecies cohesiveness or flocking behavior in some breeds of adult sheep is well recognized (Hunter,1960), age effects and numbers of sheep within and among ages independent of maternal attachment is not clear. Young ewe lambs from our New Mexico flock just weaned from their dams refused to stay with a group of adult ewes bonded to cattle (flerd). In contrast, a group of yearling ewes tenaciously stayed close to peer yearling ewes bonded to cattle (Anderson et al.,1988). In attempts to increase the numbers of young bonded lambs in flerds we observed that when group size approached or exceeded 12, lambs frequently became independent of cattle and formed small independent lamb groups. However, when the original small confinement groups were maintained as separate units until the lambs were 6 months or more of age, the small flerd could be combined into larger groups and would maintain close affinity quite consistently (Hulet,1989). Bonded older lambs, yearlings and mature ewes have been maintained in large groups (>80) with cattle with consistent close affinity of the sheep to cattle over long periods of time (>3 years). These contrasting behaviors raised the question as to the age at which the flocking instinct, independent of maternal attachment, expresses itself.