An unusually high number of female humpbacks living in the Southern Ocean around the Western Antarctic Peninsula have gotten pregnant in recent years. Humpback whales usually give birth every couple of years and have pregnancies that last for around 11 months, according to the National Oceanic and Atmospheric Administration. Once the baby is born, the mother is very "protective" and "affectionate" toward its young.
The researchers collected skin and blubber samples between 2010 and 2016 from 268 unsuspecting females. They tested the samples for progesterone — a hormone that regulates the reproductive system and pregnancy in most mammals, including humans. If the progesterone levels matched those found previously in pregnant female humpbacks, the researchers could indicate if these giants were "expecting."
They found that pregnancy rates varied greatly from year to year, from 36 percent in 2010 to 86 percent in 2014. But across all the tissue samples, on average, 63.5 percent of the females were pregnant. This is up from 48 percent of pregnant females identified between 1950 and 1956 in Antarctic whaling areas.