calving and mating
Australian southern right whales calve and mate in near-shore coastal waters. A map below shows the winter aggregation areas around Australia (DSEWPaC 2012). Southern right whales are not monogamous and can mate with many partners. On average, female southern right whales calve every three to four years. The triennial calving cycle of southern right whales has resulted in cohort structured breeding groups in Australia, causing peaks in abundance of the primary breeding group every three years. Site fidelity is high and individual southern right whales are known to return to the same location year after year to breed.
Female southern right whales have a gestation period of 11-12 months. When born, calves are around 4-5 meters in length and 1 - 1.5 tonnes. They then grow rapidly from consuming the lipid rich milk of their mothers, gaining 100 kilograms a day. Mothers decrease in weight during the calving season as a result of their own fasting and feeding of their young. Females with calves have long residency periods, remaining in the aggregation area for up to several months.