Wednesday, December 21, 2005

First Cow adopts Schnitzel's abandoned pup

First Cow (-20) is an old and experienced mother. Schnitzel is not. Schnitzel abandoned her pup one day after it was born, the same as she did last year, but last year she had a large wound that gave her some rationale in our eyes for the abandonment. Last year, her pup perished, as it is impossible for a pup to exist without a mother to defend and feed it. This year, First Cow adopted the abandoned pup and began nursing it as well as her own. One of the interesting features of elephant seal society is the pup adoption phenomenon. Pups are often separated from their mothers, abandoned, or crushed in the confusion of the crowded colony, but cows that have lost their pups are very eager to adopt newly motherless pups. We have found that younger cows are more likely to lose their pup, due to their inexperience and low social rank. However, cows that have lost their pups are very eager to adopt a new pup, sometimes even trying to steal pups from their rightful mom. It is a rare event that a cow with her own pup will accept another and suckle it as her own, but that is what First Cow is doing. Normally, the energetic demands of raising one pup is enough to tax a cow's fat stores. It appears that this is a very good year in terms of cow energy supplies. The pups that have been born this year are 10% heavier than pups born last year, indicating that the cows had plenty of rich food to eat while they were at sea putting on blubber and gestating these pups. Apparently, First Cow felt fat enough this year to raise two pups instead of the ususal one, indicating that the past year was great in terms of e-seal food supplies.

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, Beachmaster of Sandflat, Deposed by Nero

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

Earliest elephant seal pup ever recorded on Farallones

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

Elephant Seal Biology 101

Elephant seals are the biggest seals on the planet. The northern hemisphere species breeds from Mexico to northern California, but their feeding range reaches far offshore and north to Alaska. Males are significantly larger than females and also have a large, dangling proboscis (nose) that gives them their name. Adult males can weigh up to 2 tons at a lenth of 12-15 feet, and females can range between 800 to 1500 pounds at a length of about 9 feet. Elephant seals spend most of their lives in the water and are the deepest diving seals.
Here's a picture where you can see the size differences between a cow and her pup and a bull.
During the breeding season these animals haul out on land and fast the entire time. So all the energy they need to sustain themselves and give milk to their pups, plus all neccessary water for a month is provided entirely by their body fat. Cows give birth to a single pup a few days after hauling out on a rookery and nurse it an average of 28 days. In that time they manage to increase the weight of the pup from 80 pounds at birth to 200 pounds at weaning.

Mother and newborn pup

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

What's it like...

...out there on the Farallones? Well, not many of the former buildings remain. Except for two former lighthouse-keeper's residences, a powerhouse and a carpenter shop, the rest were knocked down to allow the tens of thousands of sea birds more space for breeding.

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.
Posted by: Danny

Monday, December 05, 2005

How did we get here in the first place?

Yesterday, 3 enduring biologists boarded a sailboat in San Francisco Bay to bring out needed supplies and personel to a tiny island in the stormy Pacific. The name of the island: Southeast Farallon Island, barely 1/2 square mile in size and only 28 miles west of the Golden Gate Bridge. So close, that the island is actually within city limits and is easily seen from the Golden Gate Bridge, Twin Peaks, or Marin Headlands on clear days.
What was the reason for this trip? To switch over from the shark/migratory landbird season (fall) to the elephant seal season (winter), so PRBO Conservation Science can continue the 35-year ongoing study of the Farallon seal colony. This season starts, when the big elephant seal bulls come back to the island in early December and ends in mid-March when the last of the breeding females (referred to as cows) depart.
These supply runs are provided by sail and motor boat skippers of the Farallon Patrol, men and woman who volunteer their time and (beautiful) boats to maintain the ongoing research on the island. Without their ceaseless efforts PRBO's Farallon research wouldn't be possible!

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

What are we doing here?

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.