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What are Weddell Seals?
Weddell seals are the southernmost breeding mammal on the planet. They are found only in Antarctica, and are located all around the coast of the Antarctic continent. They are true seals, of the family Phocidae. Weddell seals are one of only four species of seals that spend their entire lives in Antarctica--the other three species being the leopard seal, crabeater seal, and the Ross seal.
Found in association with "fast ice"--ice that is attached to the coastline of the Antarctic continent and islands--Weddell seals actually spend most of their time in the ocean or resting on ice flows at sea. However, every Antarctic Spring most of the Weddell seals gather in pupping colonies along the tidal and glacial cracks where the fast ice meets the sea ice. The females come in to give birth, rear their pups, and breed.
They are great divers, and can make dives over an hour long--although shorter dives are far more common. Their excellent diving capabilities allow them to travel far under the sea ice where they access the surface through tidal and glacial cracks and holes to haul out and give birth on the surface of the ice. Here, no natural predators can reach them during the Antarctic Spring, so their vulnerable new pups are safe from predation.
Weddell females begin breeding and giving birth at around 5 to 7 years of age, and live an average of 15 to 17 years old. Although, there are many females that live and give birth into their 20s, and rarely some females that live and have pups into their 30s. On average, Weddell females have around 1 pup every 2 to 3 years over their breeding lifetimes.
The Weddell moms spend around 45 days or so nursing and nurturing their pups, and teaching them how to swim. Weddell moms are frequently seen raking holes in the ice with their teeth to make ramps that will assist their pups learning to get in and out of the water as they learn to swim. Weddell moms may also be teaching their pups valuable behavioral skills that will serve the pups well as adults. Weddell males spend much of their time vying for breeding territories beneath the ice, where mating occurs after the pups are weaned and left on their own to fend for themselves. Males do not contribute toward the raising of the pups.
Here is a podcast about Weddell seals that was created by Mary Lynn Price for the Weddell Population Study, and was released by the award-winning DiveFilm HD Video Podcast.
- Mary Lynn Price
Adapted and Expanded Blog Post, 22 October 2010
About Those Weddell Seal Pups...
When it comes right down to it, the Weddell seal population study involves a lot of time focusing on Weddell seal pups. How many Weddell seal pups are born in the Erebus Bay Antarctica study area each year, how much some of those pups weigh at birth and weigh when they are weaned, how much time is spent by Weddell pups swimming in the water during the nursing period, and how many pups survive and return to have pups of their own, are all vital data gathered by the Weddell seal population study research field team.
During the nursing period Weddell pups, like the one in the photo below by Weddell seal field team researcher Jesse DeVoe, are frequently visible on top of the sea ice and are accessible to the researchers. This accessibility makes it possible for population researchers to tag the seal pups soon after birth with small identifying tags, and determine how many pups are born each year in the Erebus Bay study area.
And this year has been a great one for Weddell seal births. So far in the Erebus Bay Weddell seal population study area, "the population produced over 580 pups this year making it another in a series of high-production years," says Montana State University ecologist Jay Rotella. Jay Rotella and Bob Garrott, professors at Montana State University, and Don Siniff, professor emeritus at the University of Minnesota, are the lead scientists on this National Science Foundation funded Weddell seal population study project.
Weddell pups are born on top of the sea ice. At birth they are covered with a soft lanugo coat that does not provide adequate insulation in the cold Antarctic sea water. The pup in the photo below by Weddell seal field team researcher Jessica Farrer is very young and still wearing its lanugo.
Over the next several days after birth, the pup's lanugo coat will be replaced by a coat that is better suited to life in cold water, as with this pup in the photo below by Weddell seal field team researcher Darren Roberts.
Usually when the pups are one to two weeks old they will begin to swim with the encouragement and assistance of their moms. To ready their pups for life in the ocean world, Weddell moms spend a lot of time in the water with their pups as the Weddell pups begin to swim.
In this wonderful underwater video, Antarctic diver, imager, and musician Henry Kaiser, working with Weddell seal project B-470, captures the playful behavior of a Weddell pup swimming with its mom beneath the surface of the sea ice.
Over the remaining week or two of the 2012 pupping season in the Erebus Bay study area, the Weddell seal population study research field team will continue to look for new pups in the study area.
The B-009 research field team members will complete surveys of the entire population of Weddell seals in the Erebus Bay study area, and take final weights on a limited number of pups, before the pups are weaned and left by their mothers to fend for themselves as the sea ice begins to melt with the approaching Antarctic Summer.