Reproductive strategies of a warm temperate vespertilionid, the large-footed myotis, Myotis moluccarum (Microchiroptera : Vespertilionidae)

A population of M. moluccarum, which is known to be polyoestrous and monoto cous, giving birth to two consecutive offspring annually, was investigated to determine the female reproductive cycle. The population was visited, and observations recorded, at approximately 5-week intervals from July 1994 to February 1995. At each visit, 2-4 females were collected and their reprodu ctive tracts were removed, fixed and processed for light microscopy. During visits conducted after parturition periods, the age of the offspring was e stimated in order to determine the duration of parturition. The two gestation periods of the breeding season were of approximately equa l duration (11.5-12 weeks) despite the initial pregnancy occurring over muc h cooler months. While some copulations take place Drier to ovulation, sper m storage is not a necessity, and copulation can occur until the time of ov ulation. First ovulations of the season take place in early August and alth ough several follicles may mature only one is ovulated. Analysis of climati c variables indicates that females undergo the first ovulation and pregnanc y of the season during the cooler part of the year whereas lactation occurs during the warmer, wetter months. A post-partum oestrus occurs soon after parturition and adult males leave the population before the birth of the se cond offspring. Individual variation in the time before the post-partum oes trus may account for the reduced synchrony noted in the second parturition period. Monthly changes in the corpus luteum and ovaries are documented. The reproductive cycle of M. moluccarum resembles most closely that of trop ical and sub-tropical vespertilionids; however, pre-ovulatory copulation, a short period of sperm storage and the development of typical over-winterin g follicles (aspects of reproduction seen in species from cooler climates) remain inherent in the large-footed myotis.