Elephants Elephants - Wildpro - Twycross Zoo

day. If water is short elephants may dig holes in dry stream beds to get atsub-soil water.2.8 ReproductionSEXUAL MATURITY AND GESTATIONIn the wild, first conception can occurs between 10-12 years and calvingintervals range from three to nine years, with an average of four years (Lee1991a). It is suggested (Laws and Parker 1968) from work in Murchison Fallsthat female elephants are ready to ovulate at 11 years on average but that fullfollicular maturation and ovulation can be inhibited by physiological,nutritive or social stresses. Work in Sri Lanka suggests that first parturitiontakes place at and around 10 years, making females mature at 8 years (Kurt1974). From work in south India (Sukumar 1992) concludes that the earliestage of calving is between 12-13 but that the mean age at first calving isbetween 15–20 years. Basically reproductive rates are affected by severalfactors; quality and quantity of food supply (see next section), the presenceand sex of a suckling calf and the age of the cow. A study in south Indiasuggested a mean interval of 4.7 years with a range of 3-6.5 years (Sukumar1992) and data from Amboseli on African elephants show a mean interval of 5years (Moss 1983). However, captive elephants can commence reproductivecycles at younger ages (see Section 3.6).Gestation is 20–22 months after which a single calf is born (Estes 1991). Thereis a low rate of twinning, around 2% (Douglas-Hamilton and Douglas-Hamilton 1975). For information on gestation periods in captive elephants seeSection 3.6. Elephants are known to produce calves up to an advanced agebut cows are reputed to exhibit menopause at the age of circa 55 years (Lee1991a).In the wild, bulls mature between 12-14 years. However puberty varies withenvironmental resources (Eltringham 1982) and whereas females producetheir first calf some two or three years after their first ovulation males takesome years to reach social maturity. Work on African elephants has shownthat males are not able to compete successfully with oestrus females untilabout 25 years old (Poole 1989b).SEASONALITYThe breeding season of elephants is not easily defined and months ofconception vary from year to year. Elephants are not physiologically forced tobreed seasonally. It appears that the better the rains the more likely cows areto conceive (Douglas-Hamilton and Douglas-Hamilton 1975). In bothMurchison Falls and Tsavo conceptions were more likely to occur in wetterperiods (Laws and Parker 1968). Most research in Asia has been carried out inSri Lanka and south India where this observation has not been made (Nowak1991) (Sukumar 1992) (McKay 1973) (Eisenberg and Lockhart 1972). Howeverhigher quality foods, usually available after rains, result in improved body26