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Breeding Habits of Captive Long-Tailed Weasels (Mustela frenata)

1948; University of Notre Dame; Volume: 39; Issue: 2 Linguagem: Inglês

10.2307/2421588

1938-4238

Philip L. Wright,

Reproductive Biology and Fertility

Hamilton (1933) was the first American worker to maintain a number of weasels in captivity in order to study their life history. He kept several animals of two species (Mustela frenata and M. erminea) and obtained considerable information on the molt to white in the fall and the molt back to brown againi irthe spring. He raised litters of both species, born in captivity, and presented extensive data on the growth and development of the young. He obtained no matings but he did show that the gestation period in M. frenata is longer than the 42 days stated by earlier works to be the length of the period, since he had a female which produced a litter after being isolated for 70 days. Hail (1938) had a female frenata that produced a litter after 131 days without access to a male. In Europe Mallner (1931), Mathis and Psenner (1938), and Grigoriev (1938) presented evdience that the European stoat, Mustela erminea, had a long gestation period and in 1940 Watzka published an extensive paper on the stoat showing that the usual mating time was in June or July and that the young were born the following spring after a gestation period of 8 or 9 months. The first live female of M. frenata which I obtained was taken in Minnesota in October 1937. This animal was caged alone after that time, and it produced a litter in the spring of 1938. The gestation period in this case was at least 130 days. In the summer of 1940 an adult male of M. frenata was caged with a female from July 20 until September 1 and on May 1, 1941 a litter was born. Thus the gestation period was at least 242 days. This record together with morphological data on the structure of the unimplanted blastocysts characteristic of the long period during which time the embryos are inactive was published the following year (Wright, 1942A). Lloyd McDowell, a student caring for my animals in my absence, observed copulation between two pairs of weasels on July 2, 1941. From this time on numerous animals have been bred each summer in my colony and it is the purpose of this paper to summarize the data so obtained. The animals were maintained as previously described (Wright, 42B).