University of South Florida St. Petersburg Student Research Journal, Vol. 1, Issue 1, article 5 : Geometric Probability of Mating Success for the Greater Short-nosed Fruit Bat, Cynopterus sphinx

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Student Research Journal (USFSP)

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Publication Date


Date Issued

February 2012

Date Available

February 2012




In the bat Cynopterus sphinx, the random probability of mating success was calculated to be 4%. A combination of several adaptations dramatically increases their mating success to nearly 100%. First, the male and female hang upside down in a front-to-back mount. From behind, the male positions his penis dorsoventral toward the female's genitalia. The male maintains a tight hold on the female by biting the scruff on her neck and by holding her wings with his thumbs, allowing the pair to move forwards and backwards uninterruptedly and rhythmically. The male inserts the glans of his penis while the female bends upward, guiding his shaft to her vaginal opening.


Also includes poster presented at the USFSP Undergraduate Research Symposium, April 19, 2012.


University of South Florida St. Petersburg


Mentored by Dr. Leon Hardy and Dr. Deby Cassill

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