Nicole Teutschel at UC Santa Cruz Long Marine Lab, CA -- Their proper name is weanlings. But we call them weaners. They've finished nursing. Most have gained 150 to 300 pounds. Almost all of their moms have headed back into the ocean. And now, among the dunes, willows and nooks and crannies of the beaches, a couple of thousand weaners clump together, in twos to twenties, going through their month-long fast. And now that we've finished deploying the new set of satellite tags on 24 new females, the E-Seal team is weighing the sons and daughters of the set of previously tagged seals.

One of the reasons that elephant seal pups get so fat during their first month of life is because they need all this weight to sustain them during their fast. Mothers that are able to transfer lots of calories to their offspring produce large pups that become weaners weighing 250 pounds or more!

After the females wearing satellite tags returned to the beach in January, we removed their tags when their pups were five days old. At that time, we weighed the moms and the pups. This second weighing of the pups will tell us how successful the female was at fattening up her pup.

Coya, one of TOPPs featured elephant seals, with her 5-day-old pup. This pup weighed nearly 100 pounds when this photo was taken.

The first step in the weaner weighing is to find the weaner! Easier said than done….these little guys and gals move out of the harems to avoid being harrassed by other females and the large males. Many end up at the tops of sand dunes, in the bushes and puddles, in piles of dozens of weaners. Some undulate a quarter mile away from their harem! Here's a map of the elephant seal harems at Año Nuevo.One of the weaner piles! All these seals have been weaned from thier mothers and have gathered behind one of the harems back in the sand dunes.

Looking for the right weaner. In photo: Erin Pickett (left) and Nicole Teutschel (right).

Once we find the weaner that we’re looking for, identified by a flipper tag and/or a mark written on its fur, we carefully place it into a bag to be weighed. This specialized bag has a hole in the end, just enough for the muzzle to stick out so the weaner can have fresh air, and we can watch to make sure he or she is breathing regularly. The bag also has a pull string on one end to secure the seal in the bag so it won’t fall out when we weigh it.

That's me, securing the bag around the weaner.

After the weaner is in the bag, we connect the bag to a winch and crank it up off the ground using a large tripod. This part of the process is very similar to how we weigh the adult females.

This weaner helps the weighing process by lifting his flippers off the ground! In photo (from left), Erin Pickett, "WX4", Nicole Teutschel and Ben Cook.

This number is how much the weaner weighs -- in kilograms! So, this baby seal weighs 310 pounds!

Once we’ve recorded its weight, we crank the bag down and begin to release the little seal. When the seal is almost out of the bag, we measure its girth around its “flipper” pits (not arm pits!) and then measure its length.

Ben Cook measuring the length.

Almost done! Before we remove the bag, we place a new and second flipper tag that will also be used to identify the seal. Sometimes flipper tags fall off, so having two is better than one.

Successful attachment of the second green flipper tag. A few years from now, if we find this male on the beach, we'll know from his tag number that he was born here in February 2008.

We record the flipper tag number. In photo (from left): Nicole Teutschel and Erin Pickett.

Out of the bag! Some weaners can't wait to get away from us. Some don't care, and just stare at us, as if to ask, "What's next?" No matter what, they forget about us very quickly and go back to doing what weaners do: sleep, yell for no apparent reason, and scratch themselves while they're molting their dark fur coat off to become sleek, shiny seals.

This quick process gives us great data about how individual females allocate resources to their pups. By looking at many weight measurements over the years, we can see how the seal population is doing overall. That information gives us a baseline to work with as we compare this data with global climate change. And if there's a significant difference that appears, we can identify it, and begin to look for causes that might relate to some other human impact.