Observations of the common vampire bat (Desmodus rotundus) and the hairy-Legged vampire bat (Diphylla ecaudata) in captivity

We investigated roosting patterns, reproduction, morphometry, and ontogeny of a group of common vampire bats (Desmodus rotundus) and a group of the hairy-legged vampire bats (Diphylla ecaudata) both maintained for > 3 years in captivity. The basic social structure observed in Desmodus was of a principal colony or harem composed of females and their offspring and a few adult males, termed resident mates and a separate group of the other males, termed non-resident males. The roosting patterns of Diphylla differed little from those observed in Desmodus, but the hierarchical segregation of non-resident males appeared to be Less strict. In both species the non-resident males are accepted into the principal colony when the ambient temperature lowers. This behavior suggests social thermoregulation. Parturition of both species occurred once a year, and most of the births took place in spring or summer. The average duration of palpable pregnancy and lactation was Longer in Desmodus than in Diphylla. In both species some Lactating females that had Lost their young continued suckling the babies of other females. Desmodus is larger in size than Diphylla. This may be related to the size and type of prey; Desmodus preys principally on large mammals and Diphylla preys on birds. We observed female biased sexual dimorphism in Desmodus and isometrical sexes in Diphylla. This may be related to the differential duration of lactation and maternal care periods, as the breeding cycle in Desmodus is longer than in Diphylla. The average time of reaching maturity: epiphysis closure of wing bones, adult weight, scrotal testes, and first pregnancy, as well as the first flight time and the time when mates begin to roost apart from the principal colony, were later in Desmodus than in Diphylla. The variation between the two genera for duration of ontogeny and maternal care periods may be related to the learning needs for predation on different types of prey.