Theses and Dissertations

Date of Award


Document Type


Degree Name

Master of Arts (MA)



First Advisor

Dr. Mario Gil

Second Advisor

Dr. Valerie James-Aldridge

Third Advisor

Dr. Lucia Carreon Martinez


In May of 2015, an attempt to introduce a new silverback (adult male) to an established group of six western lowland gorillas (Gorilla gorilla gorilla) housed at Gladys Porter Zoo failed. The introduction process was halted and only protected contact among the gorillas was allowed. On May 1, 2018 another introduction was initiated to three adult females.Twelve months of behavioral data were compared across three time periods and two environments. We predicted that an increase in agonistic and affiliative behaviors would occur while anxious behaviors would decrease. We observed a significant increase in affiliative behavior and a significant decrease in anxious behavior outdoors. Significant decreases in locomotion, manipulation and stationary behaviors were also observed. In contrast to other reports, levels of agonism were low in all conditions. This second introduction attempt is judged successful. The prolonged period of protected contact and reduced group size may have facilitated group formation.


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