Hormone levels and overt social behaviors,including signed output,in a captive lowland gorilla

An investigation into the relationship between a 10-yr-old captive female gorilla's hormonal fluctuations and her overt behaviors was conducted for a 6-mo period during daily, 30-min, midday sample sessions. During each session a urine sample was collected from the gorilla and a total immunoreactive estrogen assay (E_t) was performed to obtain combined levels of estrone, estradiol, and estriol. Additionally, 38 behavioral variables were recorded on check sheets. Nearly 50% of these variables were significantly (P ≤ .05) correlated with the ape's hormone levels, thus suggesting that non-sexual overt behaviors may act as indicators of an ape's reproductive status.