Figure 3. Incidence of superfetation in the captive colony.

In 68 pregnancies, superfetation was possible because of the presence of a fertile male with a late-pregnant female between days 36 and 41 of pregnancy. In 36 of these pregnancies and in 13 out of 25 females, a second pregnancy developed (superfetation) (light grey bars); in the other 32 pregnancies in 19 different females (dark grey bars), no further pregnancy developed. Of those females in which the opportunity for superfetation arose more than once, 7 out of 9 females (77.8%) had at least one pregnancy successfully conceived by superfetation.