Communicative contexts of the LEN facial expression of pigtailed macaques (Macaca nemestrina).

We have investigated the contexts of the LEN (lips forward-ears back-neck extended) or pucker, a species-specific facial expression of Macaca nemestrina, in four breeding groups. Using the behavior sampling method we recorded all LENs, associated behavior, and the identities of the individuals involved. Of 401 LENs initiated, 62% were directed to the observer, who never responded to them in any way. Infants and dams directed more LENs to the observer than did sires or other females. The average intraspecific LEN rate was 0.82 per monkey-hour, including LENs given in reciprocation. Excluding LENs given in reciprocation, sires LENned significantly more often to females and dams than to infants, and significantly more than females and dams LENned to them. Of LENs directed to conspecifics, 21% were reciprocated, 34% were followed by distance reduction, and 16% led to both. Reciprocating LEN responses occurred more often to LENs initiated by sires. Although primarily affiliative, some LENs occurred in agonistic contexts, suggesting a possible appeasing function or rejection of a LEN's social invitation. Aggression preceded 8% of conspecific LENs, and 15% of LENs were responded to by visual aggression. No response followed 47% of LENs. Affirming the conclusions of others, LENs are often directed by males to females before mating. LENs directed at cradled infants suggest that maternal LENs serve more than a summoning function. LENs directed to people by M. nemestrina usually seem to be inviting interaction or attention, but LENs by dams seem to reflect concerns over their infants. We speculate that at the most basic level the LEN emphasizes that the sender's gaze is fixed on the receiver. We propose that the LEN may have evolved in this quiet rainforest species to facilitate coordination of social activity when silence or stealth is advantageous.

Pair housing for female longtailed and rhesus macaques in the laboratory: behavior in protected contact versus full contact.

Pair housing for caged macaques in the laboratory generally allows unrestricted tactile contact but, less commonly, may involve limited contact via grooming-contact bars or perforated panels. The purpose of using this protected contact housing, which prevents entry into pair-mates' cages, typically is to accommodate research and management requirements. The study used behavioral data collected on 12 pairs of female longtailed macaques (Macaca fascicularis) at the Washington National Primate Research Center and 7 pairs of female rhesus macaques (Macaca mulatta) housed at the Tulane National Primate Research Center to assess the relative benefits of protected versus full protected contact. The study collected data in stable pairs housed first in protected contact followed by full contact. Species combined, the study found the presence of the panel was associated with lower levels of social grooming and higher levels of self-grooming, abnormal behavior, and tension-related behavior. Within species, only the protected- versus full-contact contrasts for abnormal and tension were statistically significant-and only for rhesus macaques. Results suggest that for female rhesus macaques, potential disadvantages or inconveniences of full contact should be balanced against the improved behavioral profile in comparison to protected contact. The use of protected contact among female longtailed macaques does not appear to require the same cost-benefit analysis.