In Batu Caves, in Peninsular Malaysia. Beck and Lim observed that there was no evidence that E. spelaea had a regular reproductive pattern. More than 50% of the adult females were pregnant or lactating every month during the study period 1966 to 1968. Peak pregnancy rates occurred in May - June and October - November in 1966 and in April - May and September 1967. Parturition and lactation periods occurred during heavy and low rainfalls. High rates of parturition were recorded in June and November 1966 and June and September 1967. The weaning period finished approximately eight weeks after birth. Gestation period was estimated between 6 to 6.5 months in Malaysia and three to four months in India . By using four months gestation, Heideman projected that parturition in Negros occurred in January, May, July, September, November and December. In north-east India, Bhat et al. estimated that E. spelaea lactate for five to eight weeks. On Leyte Island, the Philippines, females carrying neonates or juveniles suggested a seasonal and synchronous pattern of reproduction . Kitchener et al. reported that two pregnant females and 60% juveniles were collected on Lombok Island in October. In May, seven individuals were pregnant and one was a juvenile. Their data indicated that birthings for the species occurred before the on-set of the rainy season in October and most immatures from the recent parturient season were flying.
E. spelaea usually roosts in large colonies in caves . The bat flies long distances in search of flowering trees; feeds on pollen and nectar . Ecologically, the cave nectar bat is found to be a major pollinator of many forest trees including the commercially important durians (Durio) in Malaysia ; . An adult female (B0213; forearm length 67.0 mm, weight 53.5 g) from Gading was netted with a Ficus species fruit weighing 13 g.