Weaner pod staying out of harm’s way up on Omega Terrace

Play-fighting

Rusty with cow and pup

We’ve seen a few success stories too. Several of the Sand Flat weaners have been washed out from the area during high swells, and a couple have fallen into Breaker Cove at the edge of the territory. We considered them as good as gone, but surprisingly, we’ve been finding the ‘lost’ weaners all around the island. One ended up on West End, a couple on Weather Service Peninsula between West End and Sand Flat, and some in gulches on the East and North sides of SEFI. Some have disappeared from Sand Flat and reappeared at other places on the island, returning to their natal beach several days later. While they may not be strong or experienced enough yet to undertake their first long trip to sea, they apparently have the capacity to remain afloat and even to swim back home after getting washed up on other beaches. We keep wondering how they get to where they end up, and imagine them setting ‘sail’ around the island.

‘Missing’ weaner with subadult male on Weather Service Peninsula

We have been tagging each of the pups as soon they wean, as well as measuring their length and girth to gain an estimate of nursing and weaning success. The measurements have been fairly consistent between the animals, ranging from 140 cm to 160 cm for length and 127 cm and 147 cm for girth. Similarly to previous years, we’ve found tha
t the weaners born on Marine Terrace are larger than those born on the crowded sand flat. With the weaners being almost as large around as they are long, they will have to lose some of their ‘baby fat’ before they can navigate the water.  Some weaners, however, are not always ready to start losing weight once they lose their mother. One of the weaners in Mirounga Beach had found a surrogate mother and suckled for an additional 19 days from its second mom. It became what we call a ‘superweaner, or ‘double mother suckler.’

Superweaner

 We have had some extraordinarily warm and sunny weather this winter, brought on by a La Nina ENSO event which causes dry and mild winter weather along the Pacific coast. One of the highs so far has been 19.5 degrees Celsius (67 degrees F). Although the humans have enjoyed the weather, the blubbery Northern elephant seals found it hard to bear. To prevent overheating on sunny days, elephant seals will often throw flipperfuls of damp sand on their backs to cool down. You will often see this on sandy rookeries such as those at Point Reyes or Ano Nuevo. With little sand or loose dirt available on Sand Flat (the sands which originally covered the area were washed away over several decades by rough storms), the elephant seals at SEFI have not been able to cool down in the same way. Instead, they were trampling each other in the mad dash for the last remaining droplets of the rain and swell puddles at the edges of Sand Flat, or for the tiny bit of shade in a narrow alley between two rock terraces.

Seals vying for the last remains of a cooling rain puddle

Cooling off in the puddle

Several of the males that are subordinate to the alphas Rusty and MC Hammer spent the warm days waiting in the alley for cows to come seeking shade. There, they were able to mate with the females without being chased off by a dominant bull. As more cows became sexually receptive, the competition between males for access to them had intensified. At the height of the season, Rusty was unable to hold down the entirety of the Sand Flat territory, and many other subordinate males were able to sneak into the periphery and copulate with females leaving the colony to return to sea. After mating with the alpha male, the cows were often ambushed by at least one other male on the way back to the water. Several of the younger subadult males, often emboldened by the older guys’ pursuits, unsuccessfully tried to sneak into the colony. We often found them later in the day resting on the terrace overlooking Sand Flat with large gashes and puncture wounds on the backs, being unable to do anything other than watch and long for the rocky, cow-filled pastures below. They’ll have to wait a few more years before they can square off with the major game players. For (a lot) more photos of the elephant seals and a personal account of an intern’s experience on the Farallons, you can check out smellephantisland.

Subadult male on Marine Terrace

 
 The winter season is almost at an end, with the elephant seal crew getting ready to leave the island in a week and a half.  Like the elephant seals, the winter biologist and interns must return to their true homes. Everyone is quite wistful about leaving, but are enjoying their last days with the seals and each other. It has been a great experience for everyone new to the island, and most of us hope to return here again soon.