Birth of Adders in Captivity

Abstract

THE adder (Vipera Berus) has her young about the end of August and the first week in September. The gestation period is 4½ months. It is unusual for a herpetologist to have a captured snake giving birth to young immediately after being caught, but such has been my experience on two occasions, the first on Aug. 29, 1905, and the second quite recently, on Oct. 1, 1928, the latter birth being on a later date than normal. The adder in this case was a healthy specimen measuring 23 inches in length. On being caught I noticed that it was a bit sluggish and lethargic in its movements, making very little effort to escape. There was nothing in its contour to suggest pregnancy beyond being slightly corpulent, and I was certainly very much surprised to find on opening its cage one morning eight days after capture a brood of eight young adders. They measured 4½ inches in length and six are females and two males.