Birth Sex Ratio and Determinants of Fecundity in Female Timber Elephants of Myanmar

I assessed the reproductive patterns of captive-born and wild-caught Asian elephants managed by the Myanmar Timber Enterprise. Calving among all female elephants was seasonal with higher births in cool months (October to February) and late monsoon (September). Captive-born mothers have significantly higher fecundity rates with lower inter-birth intervals than wild-caught mothers, likely due to harsh capture and breaking procedures, and inadequate nutrition due to unfamiliarity of foraging grounds and fettering during night foraging. Fecundity peaks between 22 and 25 years, levels out between 25 and 39 years and gradually declines after 40 years in both wild-caught and captive-born females. Complete reproductive cessation is not observed until age 60 in wild-caught mothers and at least age 49 in captive-born mothers, suggesting reproductive senescence is not likely in either captive-born or wild-caught females. Offspring sex ratio is not different from unity and not influenced by birth order of calves, mother’s birth origin or age.