URINARY CORTISOL PROFILES THROUGHOUT DEVELOPMENT IN MALE MARMOSETS
J. A. French, K. T. Phillips, and B. J. Proskocil
Nebraska Behavioral Biology Group and Psychology Department, University
of Nebraska at Omaha, Omaha NE 68182-0274.
While a good deal is known about changes in gonadal hormone
production throughout development and its modification by social factors
in callitrichid primates, less is known about maturational changes in adrenal
steroid hormone production. We present data on profiles of glucocorticoids
in male marmosets to address this shortcoming. Urine samples were
collected noninvasively from males residing in their natal family groups
(n = 24) at ages varying from 1.2 to 35 months. For reference purposes
we also measured urinary cortisol concentrations in a sample of breeding
adult male marmosets. A cross-sectional sampling strategy was utilized,
so not all males contributed samples at all age-points. Urinary free
cortisol was measured via EIA. Levels of cortisol were higher in
young infants (less than 3 months of age; > 40 mg Cortisol/mg Cr) than
in any other age class, including adult males. After 3 months of
age, levels drop to low concentrations (~ 10 – 15 mg/mg Cr) and remain
low thereafter. While urinary testosterone peaks in sons at 12 months
of age, there were no corresponding changes in cortisol excretion.
Compared to sons in family groups, breeding adult males had significantly
higher concentrations of urinary cortisol. As is the case in daughters,
then, reduced gonadal function in sons is not associated with elevated
cortisol, and must be mediated by mechanisms other than the HPA axis.
Supported by NSF (IBN 97-23842).
GROUP NEST COUNTS IN WESTERN LOWLAND GORILLAS (GORILLA GORILLA GORILLA),
MONDIKA RESEARCH CENTER, CENTRAL AFRICAN REPUBLIC
P.T. Mehlman and D. Doran
Department of Anthropology, Stony Brook SUNY, Stony Brook, NY 11794.
Observations of 432 nighttime group nest sites (3309 individual
nests) were made between 1995-1998 in a 502 km site in the Dzanga-Ndoki
National Park, CAR. With the aid of Ba’Aka trackers, fresh nest sites (<2
days) were located while tracking groups leaving trail in the rainforest.
Nests were classified as adult silverback male versus all others (adult
females, blackbacks, juveniles) on the basis of dung size and absence/presence
of silverback hairs. Infant dung was not reliably found in all nest sites
that included known infants, but was scored when found near mothers’ nests
(approximately 10% of sites). For nest sites in which number of silverbacks
and nonsilverbacks could be identified (317), mean number of silverbacks
nests per site was 1.2+0.4; 81% of these group sites contained only one
silverback (n=256) and 19% contained two silverback nests (61). Mean minimum
number of nonsilverback nests per group site was between 5.6+3.3 (minimum)
and 6.5+3.5 (maximum). Minimum number of total nests per site (with
dung near each nest) was 6.8+3.4. Maximum number of nests (with and without
dung) was 7.7+3.6. Nest site counts ranged in size between 2 and 20 weaned
individuals (single male nests excluded). These results indicate mean group
size in this lowland gorilla population is 7-8 weaned individuals. Supported
by National Science Foundation (SBR-9422438) and SUNY, Stony Brook.
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