Gestation period of the woodchuck Marmota monax [Période de gestation de la marmotte des bois Marmota monax].

Résumé

A pair of woodchucks were captured near Geneva, New York, as young from a single nest after the mother had been hit by a car in the spring of l948. The two young were first raised on a bottle and later fed dog biscuits and greens. They were kept in a divided cage on the unheated sunporch in Etna, New York. The two spent the winter in separate cages, only being allowed to come out for exercise when they awoke together throughout the winter. Usually one was asleep when the other was awake. On March 21, 1949, when the male had been awake for several weeks and active on warmer days and the female had been awake for only a week, the two met outside the cage and showed an interest in each other for the first time since fall. Each day for the following week the two woodchucks played with each other and romped around the sunporch always under close supervision. Not once throughout this time did the male attempt to mount the female. His testes were conspicuously descended by this time, not having been obvious when he first emerged from hibernation. The morning of March 29 when the woodchuck were let out for play they immediately entered each others cages and investigated them thoroughly. The male soon returned to his own cage where the female was still snuffling around in the shavings on the floor. Upon entrance of the male the female rose on her hind legs and the two "boxed" for a few seconds. The male immediately mounted the female, who assumed a position almost like her hibernating position, nose tucked down under her chest, eyes closed, but tail up. The male gripped her fur with his teeth about half way up her back. Copulation continued for about eight minutes, then they separated for a few minutes while they-preened a little, then he mounted again for five minutes. After another interruption of several minutes the male again mounted for three minutes after which they lost interest in each other and were placed in their respective cages. From this day on the two woodchucks were not allowed association with each other at all and only one was exercised at a time. The female became increasingly more fussy and by the 28th day after mating she was very difficult to handle. From this day on we simply furnished food and water and did not allow her out of the cage. The first young was born sometime between 7:00 and I0:00 P.M. on April 29, making the gestation period in this case 3l days and about I0 hours. Four young were born throughout the night, but due to the hot spell at the time none lived longer than five days. Within two days after the loss of the last young, the female was quite tractable, and permitted herself to be picked up without biting.