2013

Specifics of Forest Fauna Gestation

The continuation of species begins with the mating season and conception and is followed by gestation. The duration of the embryonic period varies from species to species. For example, the smallest of predatory animals – weasels give birth to their offspring after five weeks of gestation. For the largest of the ermine – badgers, around nine months are needed to conceive and give birth to offspring. Young badgers are born at the end of February or in May. After two or three months, their mothers are ready for another gestation period. These cubs will be born at the end of winter. Badgers gestate around nine months because their embryos do not grow or develop in wombs during a considerable amount of time in autumn and winter – the so-called long latent period. Therefore the overall duration of badgers' gestation does not match the actual duration of their embryo development.

The same goes for martens – their latent period sets in shortly after conception. The breeding season starts at the end of June or in July. Their embryos, however, begin to develop only at the end of February or the beginning of April. Young martens are born next March or April.

Latvia’s canine predators do not have a latent period. These three species have similar gestation periods. Wolves gestate 62 to 64 days, raccoon dogs – 58 to 63 days, foxes – 49 to 58 days. Lynxes gestate around 70 days.

Despite being the smallest representatives of their order in Latvia, roe deer have the longest gestation period among Latvia’s even-toed ungulates – ten months. Compared to several larger species of the same order, it is a long period, since roe deer embryos develop longer than the duration of roe deer gestation. Their latent period lasts from conception (summer) until October or November. Red deer or elk do not have breaks in embryonic development – their gestation lasts eight months.

Wild boars have to wait less – their gestation averages to three months, three weeks and three days. European hares have acquired special adaptation skills from nature – they can mate while their young ones from previous partners are still in their wombs. Sometimes, their wombs simultaneously contain nearly fully-developed embryos and those only beginning to develop. Thus hares are capable of giving birth two to three times per year. Their gestation lasts approximately six weeks.

Squirrels give birth to offspring only once per season. When their young leave, they mate again. Squirrels gestate 38 days on the average. Both species of hedgehogs also tend to gestate once per season. However, if conditions are particularly favourable, some hedgehogs give birth two times per season. Hedgehogs gestate around one and a half month.

Several species of bats have peculiar methods of taking care of their genes. For example, long-eared bats give birth to their only offspring in June – three months after conception, which takes place in April. It may seem like no big deal, but it is necessary to take into account that these animals mate in autumn or winter. Sometimes, male bats mate with hibernating females. This means that insemination takes place in autumn or winter, fertilization – in spring. Spermatozoa, which ripen in male bats’ gonads, become dormant after entering female bats’ genitals. In spring, when ovules ripen and ovulation takes place, gametes combine.

Northern birch mice are just as interesting. Their gestation lasts four to five weeks, which is uncharacteristic of small rodents. In comparison, young dormice are born after 25 days of gestation.