Abstract # 114:

Scheduled for Friday, August 19, 2005 11:15 AM-11:30 AM: Session 8 (Mayfair Room) Oral Presentation

Functional significance of urine washing in captive tufted capuchins (Cebus apella)

K. Laszlo, K. E. Miller and S. J. Suomi
NICHD/NIH, Laboratory of Comparative Ethology, National Institute of Child Health and Human Development, NICHD, NIH Animal Center, PO Box 529, Poolesville, Maryland 20837, USA
     The function of urine washing, a behavior prevalent among prosimians and New World monkeys, remains unknown for numerous species, including Cebus apella. Results from our previous study (June 2003-April 2004) indicated that urine washing did not serve as a thermoregulation mechanism or in communication related to sexual encounters. Therefore, in the present study, we collected focal data on 26 individuals in a social group (October 2004-January 2005, 80.3 visible hrs) to examine additional hypothesized functions of urine washing, including communication related to intragroup aggression and territorial advertisement. We tested for correlations between urine washing rates and aggression and compared urine washing rates at peripheral vs. nonperipheral enclosure locations. We found a positive correlation between frequencies of aggression given and urine washing, for high and low ranking animals (Spearman rank correlation, high (n = 9), r = 0.85, P = 0.01; low (n = 15), r = 0.57, P = 0.03). We also found a positive correlation between frequencies of aggression received and urine washing for low ranking animals, but not for high ranking animals (low (n = 15), r = 0.64, P = 0.01; high (n = 9), r = 0.13, P = 0.74). In preliminary analyses, urine washing rates did not significantly differ at peripheral vs. nonperipheral locations (Wilcoxcon matched-pairs, N = 26, average (peripheral) = 0.41, average (nonperipheral) = 0.49, T = 103.0, P = 0.07). Capuchins did not concentrate urine washing at “territory boundaries,” indicating that urine washing is unlikely to advertise territoriality. Urine washing rates were related to aggression, indicating that urine washing may serve in communication during intragroup aggression.