The entire field team, now including lead Principal Investigator Dr. Jay Rotella and Co-Principal Investigator Dr. Bob Garrott, is working long hours on the ice to keep up with the numerous new pups that are being born every day. "We are in camp with a team of 8 and the pups are starting to be born at a pretty rapid clip--we’ve tagged about 160 pups so far and are putting out lots of swim tags, and weighing lots of pups and moms," Jay Rotella says. That's a whole lot of work with so many new pups!
The Weddell seal pupping season is now well underway, and will continue through most of November. Weddell moms give birth at different times during the pupping season. To be born early or late in the pupping season presents a number of challenges. If a pup is born very early in the season the outdoor temperatures are lower, and the weather is often more inclement. If a pup is born very late in the season, the ice may begin to break up and disrupt the nursing period. With the breakup of the ice comes Weddell seal predators such as Orca and leopard seals--a very dangerous situation for pups. This season the sea ice edge is quite a bit closer to the pupping areas. This may mean that the sea ice will begin to break up and melt off earlier than usual. Keep an eye on this blog to find out how this all plays out this season.
In the photo above, field team members get ready to head out from the remote sea ice camp to the various pupping colonies scattered around Erebus Bay. On the right in the photo, you can see the kitchen hut where meals are prepared and served, and computer work done on the day's collected data. Mt. Erebus is in the background, its rim sporting a bit of cloud cover. Snowmobiles are used to get to the colonies to look for new pups to tag and weigh, as well as to replace missing or broken tags on some of the adult seals. The field team also travels around to all the colonies to do regular pup and entire Weddell population surveys to determine the total number of pups and all seals in the study area. Some of the team will also be taking series of photos from different angles of some of the moms for 3D processing to determine moms' weight. Genetic samples will be collected from known age seals; and the Weddell population scientists are looking forward to future assessment of these genetic samples.
The photos above and below are of field team members in action preparing to tag a pup and enter data about the seal into a small handheld field computer. The field computer will let the researchers enter data on when the pup was born, who its mother is, the location of birth, the pup's gender, and its weight at three different points during the nursing period. For many pups, whether they received a small temperature/time recording tag will also be entered. With this information added to the project's extensive multidecade database the researchers will be able follow each seal throughout its lifetime, and use powerful statistical methods to make new discoveries about what environmental factors and seal characteristics matter more than others in seal survival and "recruitment" (meaning, whether the pup survives to adulthood and returns to a colony to give birth to a pup, itself). The entire project database covers many generations of Weddell seals. Extensive maternal genealogies can be determined for many pups born into the study area. All of this from tagging all the pups at the time of their birth!
The photo above is of the first South Polar Skua seen by the field team this season. Skuas are very bold gull-like birds that are often seen flying over or walking about in the pupping colonies looking for seal birth placenta to make a meal of or squabble over.
- Mary Lynn Price