Wednesday, December 21, 2005
PRBO has had the priveledge of working on the Farallones since 1965. We have observed the many species of seabird and marine mammal that breed here for 40 years. These datasets are some of the longest runs of biological data in the world, and they allow us to see how the ocean has changed over that time period through changes in the animals. The scientific research we conduct informs the managers at the US Fish and Wildlife Service, National Oceanic and Atmospheric Administration, and other agencies around the country, and the world so the rich biological treasures of the Farallones and elsewhere can be preserved for future generations. We increase our understanding of how the ecosystems of this planet function through science, and long-term data such as we collect at the Farallones offer rare insight into how ecosystems change through time.
Sunday, December 18, 2005
JD, previously undefeated beachmaster of Sandflat harem for the last two years and sire of perhaps 180 pups, was soundly defeated and deposed today by a young bull named Nero from the Point Reyes colony. Nero held a small harem of eight cows last year on the Marine Terrace, but has definitely moved up in the world with the outcome of today's bout. Cow elephant seals can only mother a single pup each year during a breeding lifespan of 10-15 years, but in two years JD probably fathered ten times more progeny than any cow possibly could. But that fecundity has a price, a short brutal life of ceaseless battling for dominance. This sort of breeding system is what produces such secondary sexual characteristic oddities as the Elephant Seal nose, Elk antlers, and male Fur Seals that are 5 times larger than females, the biggest difference between the sexes of any mammal.
Thursday, December 08, 2005
Today saw the birth of the first elephant seal pup of the year. Born to the female named Giovanna, her pup is the earliest recorded birth in the 35 years of this colony's existence. Here is a video of the newborn crying to her mother, while JD, the alpha bull and probable father looks on. Giovanna will now nurse her pup for about 28 days on the richest milk of any mammal, swelling the pup from 60 pounds at birth, to over 300 pounds at weaning. During that time the mother will shrink, as she mobilizes her blubber to give to her pup.
Back at the end of the 1800s, Elephant seals were hunted for their blubber to the point where they were believed extinct. Only 50-100 animals remained on the planet, hidden on Isle de Guadalupe in Mexico. The Mexican Government protected the seal from further hunting, and their numbers grew until in 1971, the first pup was born at the newly-recolonized Farallon Islands. The Farallones and Point Reyes are now the northernmost breeding colonies for this species, although the adults range much farther north, even to Alaska, to feed themselves between visits to the Farallones. Similar to Gray Whales, the elephant seal migrates to Alaskan waters to gorge themselves on the rich feeding grounds there, then comes south to give birth in Mexico and California (Gray Whales used to calve in San Diego's Mission Bay). However, the whales migrate up and down once a year, while the elephant seal makes this migration twice a year! This makes them the mammal with the longest migratory distance travelled each year, over 13,000 miles for some males!
Conserving these amazing long-distance migrants requires the cooperation of 3 national governments, 8 state/provincial governments, and the many agencies and NGOs that look after our ocean and coastal resources along that route. PRBO Conservation Science, the US Fish and Wildlife Service, and Gulf of the Farallones National Marine Sanctuary are the local partners who have an interest in the Farallones and their magnificent elephant seals.
Wednesday, December 07, 2005
Then the cows return to sea, leaving their now weaned pups behind. Male elephant seals will stay on land not just a month, but the entire breeding season of about 100 days, fasting all this time. It is no wonder that this physiological stress, combined with their ferocious fighting for mating privileges, restricts a male life span to only 10 - 12 years. Females on the other hand, can live to over 20 years of age, generally producing a single pup each year, starting to breed between age 3-6. Elephant seals are physiological marvels, fasting twice a year during the breeding and molting haulouts, migrating vast distances twice each year between these haul outs, and diving to depths where steel is crushed.
A healthy weanling
The weanlings left behind molt their long black lanugo fur to a short silver coat soon after their mothers depart. They remain for a month or so, learning to swim in tidepools and shallow coves at night. When their hunger finally triggers their departure, they swim along the bottom. These behaviors are thought to be adaptations to shark predation pressure. White sharks are daytime ambush predators that strike prey near the surface suddenly from below. The weanlings will return to the Farallones in the fall to molt again, and that is when you will learn about the sharks and their seal prey in realtime.
Posted by: Danny
This is a map of the Southeast Farallon Island and West End, the adjacent island that is separated from SEFI by a 15-foot gap called the Jordan Channel. All the island's 'hot spots' for elephant seals are highlighted in pink. The main colony is found on Sandflat, Mirounga Beach and the Marine Terrace above Sandflat, a convenient 2 minute walk from our residence. As you can see there are also elephant seals on West End. Because of the fragile nature of West End ecology (many Common Murres and the endangered Steller sea lions can be found there) we keep the visits to this place to a minimum, only going there once every 10 days.
These two houses are the living quarters for PRBO and Fish & Wildlife personel. Although they were built in the 1870's they have since been remodeled and now offer all the comforts of the modern world such as hot showers, indoor plumbing (including our very own sewage system) and internet access.
And then of course on top of Lighthouse Hill (elevation 330 feet) is the Farallon lighthouse, the first lighthouse to be errected in California because the Farallones proved to be such a hazard to shipping traffic.
Here's a view from the lighthouse towards West End showing the residences at the bottom of Lighthouse Hill.
When this picture was taken in early December the rainy season had just started and the vegetation was just starting to recover from the drought of summer and fall. When we post more pictures of the island during the season you will notice the Farallon flora exploding with life.
This is one of my favourite spots on the island, Fisherman's Bay with it's impressive rock arch (incidently called 'Arch Rock') and the so called 'Sugar Loaf' on the right. You can also see one of the more recent island improvements, the newly errected North Landing crane, our back-up plan should the conditions at East Landing not allow a landing there.
Monday, December 05, 2005
After a smooth 4 hour sailing cruise due west, the island finally was in sight, our new home for the next 3 1/2 months.
Thursday, December 01, 2005
Southeast Farallon Island Studies
The goal of PRBO's Farallon Island project is to understand, protect and conserve the island ecosystem and its globally significant marine bird and mammal populations.For over 30 years PRBO scientists have provided year-round stewardship to wildlife on these islands through a cooperative agreement with the U.S. Fish and Wildlife Service. PRBO's intensive research has produced the longest data set on seabirds and marine mammals in North America and hundreds of scientific publications, reports and popular articles. This information lays the foundation for understanding, protecting, and conserving this vital component of the California Current marine ecosystem.
Southeast Farallon Island-"Galapagos" of the U.S. :
The Farallon Islands are home to the largest seabird and marine mammal colonies in the continental United States south of Alaska. Established as a National Wildlife Refuge (NWR) in 1909, the Farallones and surrounding ocean environment have been recognized by the United Nations and governmental agencies as a site of hemispheric biological importance and have been designated as an International Biosphere Reserve, a National Marine Sanctuary, and a State Ecological Reserve. For more information, maps, and images of the Farallon National Wildlife Refuge, download a copy of US Fish & Wildlife Service's Farallon NWR brochure. To read more about the Farallon NWR and PRBO's science, visit our In the News page.