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Next Contents Vol 9 1. Abstract The gestation period in the humpback whale is of almost 12 months' duration, most conceptions occurring early in August with parturition at the beginning of the following August.
View Dimensions. Subscriber Login Username: Password:. On July 26 , they announced that a killer whale identified as L72 was pregnant. Soon after, they delivered news that Tahlequah, whose traumatic journey with her dead calf captured international attention two years ago, is also expecting.
The world erupted in celebration. Adding newborn whales to the endangered southern resident population, which has dwindled to 73 animals, would be a big deal, and Fearnbach says she can now confirm there are pregnancies in all three pods that make up the population.
But Fearnbach, marine mammal research director of Sealife Response, Rehabilitation and Research, and many whale researchers like her hesitate to celebrate. Scientists usually avoid announcing pregnancies at all, but Fearnbach and Durban felt the announcement could reinforce their call to give whales more space and inspire more formal requests from management agencies.
Knowing about an orca pregnancy means holding your breath. Orcas having one of the longest gestation periods of any mammal, and the southern residents have very low birth rates. There have been only two births in the three southern resident pods since Tahlequah lost her calf. Dawn Noren , a physiological ecologist and a research fishery biologist with the National Oceanic and Atmospheric Administration.
Each stage of early orca motherhood comes with physical and emotional hurdles, and negative human impacts on Puget Sound make things even dicier. Expectant orcas gestate for 18 months, with six-month trimesters. Most knowledge of pregnancy comes from the veterinary study of captive orcas. Detecting early pregnancy requires blood- and urine-based hormone tests on animals in captivity, or taking breath or fecal hormone samples in the field from 6, to 8,pound females.
As she lowered her flukes to a horizontal position, the calf's snout was seen to be emerging from her belly. The mother shifted to a belly-up position, just at the surface, as the calf continued emerging; then the mother submerged, and the calf popped up to the surface, separate from its mother. Bottlenose dolphins are thought to usually deliver their calves tail-first, but head-first deliveries have been observed in captivity. In a captive situation, the dolphin mother typically uses her tail and rostrum beak to guide the baby to the surface for its first breath of air.
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