Evaluating the Utility of an Accelerometer and Urinary Hormone Analysis as Indicators of Estrus in a Zoo-housed Koala (Phascolarctos cinereus)
Maressa Takahashi,1 Jennifer R. Tobey,1 Corinne Bacon Pisacane,1 and Chris Hamlin Andrus2
1Center for Conservation and Research for Endangered Species, Zoological Society of San Diego, Escondido, California
2Collections, Husbandry and Science Department, San Diego Zoo, San Diego, California
Induced ovulators, such as the koala, do not always have overt signs of estrus, which makes pairing these animals for breeding purposes difficult to achieve in a zoo setting. This study examined the possibility of using alternative methods to behavioral sampling and weight fluctuations for monitoring estrus in a female koala of reproductive age. We attempt to gain an improved understanding of koala estrus and enhance our ability to detect it by combining a noninvasive technique for hormone analysis with a newer method for recording activity level. The findings suggest that activity levels were accurately measured using an accelerometer and increased activity was associated with one estrus behavior, bellowing. Weekly weight declines occur with increases in activity registered from the accelerometer. We also validated an assay to detect progesterone and estradiol in female koala urine in an attempt to detect an estrus spike. However, neither urinary concentrations of estradiol nor progesterone was associated with behavioral cues of estrus in our subject. We suggest that increased female activity, bellowing, and weight loss all indicate a pro-estrus state that requires proper male stimulation in order to achieve a full estrus display.