Ocean Research Voyage

My time on the Farallon Islands ended with an exciting excursion to West End.  The entire team geared up for one of the few annual trips to West End, officially known as Maintop Island.

To cross the channel separating the two islands we used a bosun chair.

It is separated from the main Southeast Farallon Island by a narrow gorge.  The majority of the year West End is not visited due to the high concentration of breeding birds and mammals.  A few times a year however, biologists visit West End, especially now that we are in the peak of the elephant seal breeding season.  There are two elephant seal colonies that we need to check on.

California sea lions rule West End.  I have never seen so many sea lions in my life.  They are packed into every inch of space.  We scramble high along the cliffs to avoid disturbing them, but they are even on rock outcroppings high above our heads.  While heading to the elephant seal colony we try and collect as much sea lion data as we can, counting animals and reading brands and tags.

We pass several thousand California sea lions.

The most exciting part of the trip for me was to see Northern fur seals up close, because they had virtually disappeared from the islands for more than 150 years.

Although I have seen fur seals from boats, it was refreshing to see them at home (all 8!) on the islands.

In the 1800’s, sealers slaughtered hundreds of thousands of them for their thick fur, driving them the islands.  Now the Farallons have become a refuge for this vulnerable species.  In 1996, Northern fur seals started breeding again on the Farallons and the population is rebounding.

It was hard to leave the Farallon Islands.  I feel lucky to have spent time at such an amazing, thoroughly wild place, one of the last places on Earth where humans are just visitors.

My parting look at my home for the past 3 weeks.

The Farallon Islands are home to the largest concentration of breeding seabirds in the lower 48 states.  Although it is not currently seabird breeding season, it is already hard to sleep at night with the cacophony of screeching Western Gulls and creaking Cassin’s Auklets.  Seabird breeding season starts in April, but birds are already arriving on the island “prospecting” – searching out nesting sites and mates and claiming their territory.  The island is covered with markers designating nesting sites, some are natural burrows and some are man-made nest boxes.

Western Gulls will return to the same mate and nest each year. This marker indicates a nest from a mated pair, one was born in 1994 and one in 2003.

Three times a week we survey the island for Burrowing Owls, part of a study to determine the owl’s impact on Ashy Storm-Petrels, one of the island’s most important breeding seabirds.

The Burrowing Owl at Corm Blind Hill.

Ashy Storm-Petrel numbers are declining, and the majority of the world’s population breeds on the Farallons.  There are currently eight Burrowing Owls on the island, which predate Ashy Storm-Petrels. It is thought that they over winter on the islands due to the introduced mouse population.  Owls are banded and/or tagged with radio transmitters to determine if the same owls are year-round residents or are migrating through.

At the elephant seal colony, the pups are getting fatter.  Pups nurse for about 30 days, gaining almost 10 pounds a day from their mother’s milk.  As the pups grow bigger we watch the cows get smaller and smaller – she fasts the entire time she is at the colony.   Once the pups are big enough, the cow will return to sea and leave her pup to fend for itself.  Before she leaves she will mate with the alpha bull.  Once the cow leaves the pup is officially called a weaner.

It is amazing how big the weaners are compared to the newborn pups.

We now have two weaners at the Sand Flat colony.  They will stay at the colony for two months, learning to swim and forage before they set out for a life at sea.

The weaners are tagged with flipper tags so biologists can identify individuals.