There are five species of pinnipeds that breed on the Farallones – a high concentration of diversity for the region.
The Farallones consitute prime habitat for these marine mammals, perched near the edge of the continental shelf and thus an important upwelling zone that supports a wide web of marine life – life that in turn feeds and supports other life. The Farallones (also known as “California’s Galapagos”) is only the tip of the iceberg in this expansive marine trophic web, and one that is readily available for biological study and monitoring of the surrounding marine ecosystem. The rich concentration of life on these granite outcroppings 26 miles from the Golden Gate Bridge is unmatched anywhere else in the contiguous United States.
While I spent my time on the Farallones during the “seabird season” which takes place from March to August, and our primary focus was on the seabirds, we kept an eye on the abundance and habits of the pinnipeds on the island.
California Sea Lion (Zalophus californianus)
These charismatic sea lions are a constant presence experienced throughout the island – whether by sight, smell, or sound. They are entertaining to watch, although they are incredibly flighty and our movements around the island were often limited by avoiding hauled out groups which, when disturbed, can make a panicked stampede towards the water, with the possibility of hurting themselves and others, as well as causing undue stress. We recorded all of these instances in our nightly journal as part of the federal permit to conduct research on the island.
resting California Sea Lion
Little is known about the historical numbers of Zalophus that resided on the Farallones before human exploitation of fur seals opened up much of the island for them. Without a doubt, they now are the dominant pinniped species on the island, although they may be starting to be slowly pushed out of certain areas by the rebounding Fur Seal population.
Numbers this year were at an shocking high – literally hundreds more animals present – and it is probably due to the El Nino conditions making food resources hard for them to find, and thus they may be converging from different areas on the traditionally food-rich waters around the Farallones. In addition to the increased numbers around the Farallones, this year saw a huge increase in the number of strandings around the California coast. Marine mammal rescue groups around the state were overwhelmed with the numbers they were trying to rehab (and subsequently release back into food-poor waters). Check out this post for more information.
Observations on the Zalophus was limited for us seabirders to reporting tags and brands, as well as any animals with entanglements.
Steller’s Sea Lion (Eumetopias jubatus)
These largest of eared seals (Otariidae) are named after the German naturalist and explorer Georg Wilhelm Steller, who first described them in 1741 while on Russian Captain Vitus Bering’s ill-fated Second Kamchatka Expedition. Prior to Russian “discovery”, these animals were often food items for Native American populations. However, after Russian exploration of the Aleutians and Pacific NW coast, exploitation followed – Steller’s were no exception, and their population plummeted. Fortunately, they never went extinct (unlike Steller’s sea cow) and in 1972 they gained protection under the Marine Mammal Protection Act and the Endangered Species Act. In the 1980s and 1990s their numbers plummeted once again, from around 300,000 individuals, and no one was able to figure out why although fishery depletion is the likely culprit. They remain federally threatened, with current global population numbers around 75,000-80,000 individuals.
Steller’s are the largest sea lion species in the world (and fourth largest pinniped after N and S elephant seals and walrus), with females growing larger than male Zalophus, and males growing up to three times the size of females at 3 meters long and 700 kg. The Farallones constitutes one of the most important Critical Habitats (haul out sites and rookeries) for this species.
The above picture was one of the first times I saw these animals for their size – look at the nearby California sea lions for scale (!!!).
They are social beasts and fraternize frequently with Zalophus on the Farallones.
male Steller’s chasing a female California sea lion
They are opportunistic, mostly piscivorous and target salmon, cod, herring, and other fishes, which they will hunt for up to 600 feet deep on a single breath they can hold up to five minutes. Their breeding season takes place in the late spring and summer, and females give birth to pups around February. They stay with and nurse their pups for around a year.
Most opportunities to see these spectacular animals were from afar, although once in a while I would be pleasantly surprised to see one hauled out with the California sea lions at North Landing. At first glance it can be hard to tell younger Steller’s apart from California sea lions, but features like a shorter (bear-like versus Zalophus’ dog-like) snout, wider forehead, and overall bulk stood out after some time.
Northern Elephant Seal (Mirounga angustirostris)
Elephant seals are probably one of the most interesting marine mammals on the planet. They make one of the longest migrations of any marine mammal, 11,000 miles for females and 13,000 miles for males, semi-annually. They only come on land to molt and to breed. They spend up to 90% of their lives underwater, up to 5,000 miles offshore, and are rarely seen at sea because they are constantly diving for food (mesopelagic fish, squid, rays, sharks, rockfish). They are able to dive to depths of up to 2,500 feet, holding their breath for up to 20-30 minutes at a time. Their dive intervals are incredibly short, often only 3-5 minutes to re-oxygenate before they make another deep dive – doing this over and over in the course of a day. The physiology of their diving behavior is a topic of intense study, and it is SO. COOL.
tagged E-seal pup
There are two species of elephant seal – Northern and Southern (residing around sub-Antarctic islands). They are the largest pinnipeds on the planet, with Northern being slightly larger than Southern. Males can grow to be up to 15 ft large, weighing up to 4,500 lbs. The females grow up to 10 ft long and 1,500 lbs – a third of the mass of males – this is the most pronounced sexual dimorphism in the mammalian world. Their name, referring in part to their mass, also refers to the proboscis of the adult male, with which he attracts females and intimidates other males, inflating it and making a variety of sounds.
On the Farallones, elephant seals are primarily studied during the winter pinniped season taking place from December to March. However, during the rest of the year, elephant seal surveys take place every three days, where biologists search the usual e-seal haul-out sites at low tide for tagged seals. At the beginning of the seabird season, from March to May, there were many more e-seals present and the survey sometimes took a couple of hours to complete. This was mostly due to waiting for a tagged seal to move in a way that revealed the precise tag number and location. The numbers on the tags were often completely faded away, but often a second method of identification existed – a pattern of drilled holes corresponded to the individual’s unique alphanumeric code, although this was only true for seals tagged at certain locales.
The e-seals were by far the least shy pinniped on the island. They seem to be completely fearless of humans. Our presence only warranted a lifted head, wide-eyed gaze (whose wet, dark, seemingly pupil-less eyes sometimes seemed to bore into your soul) and a few grunts, groans, and squeals. At Sewer Gulch we could walk down to the edge of the small cliff and be only a few feet away from them – great for reading tags (and for feeling at one with the beasts). This behavior meant they were (literally) almost hunted to extinction in the 19th century for their oil-rich blubber. There remained only a small population of 50-100 individuals in the Guadalupe Islands off Baja California before the US protected them around 1920.
During my time on the Farallones, I saw only one bull from a distance. This was one of the first days that I arrived in March, and after that I never got to see another adult male. This was because during this time, the males had returned to the open ocean to forage and feed, and wouldn’t return to land again until late in the fall to set up territories and breed. While the females and young are on a different molt/feed schedule (one of the mammalogists told me it was like the males and females are two different species with such different natural histories) and were present on-island the whole time I was there (although in changing number). Males are intensely competitive and aggressive towards eachother, and a single successful dominant male (“beachmaster”) will mate with up to 50 females on his stretch of beach.
These animals are truly fascinating, one of my favorite “weirdos” out there.
Their use of the Farallones attracts the presence of another animal – one that preys on these huge, blubber (read: energy) filled animals – the white shark. But thats another story…
Great White Shark – photo via Creative Commons
Northern Fur Seal (Callorhinus ursinus)
The story of the Fur Seal on the Farallones is a story of near-extinction, but with a happy ending currently playing out in a rapidly rebounding population.
The species likely once dominated the Farallones but due to relentless hunting (by the fur industry) cause the population to all but disappear in the early 19th century.
Fur seals are actually eared seals, in the same family as sea lions. They evolved such dense fur (up to 300,000 furs per square inch) as they lack a thick blubber layer to keep them warm in the chilly waters of the Pacific. This allows them to spend most of their lives at sea apart from their breeding/pupping season. It was this dense fur the American fur hunters targeted during hunting efforts starting in 1807. Up to 150,000 fur seals were killed in a five-year period, and this was later compounded as Russian hunters got in on the action. For 150 years, fur seals were completely absent from the Farallones. In 1911, some protection was afforded them by the International North Pacific Fur Seal Treaty, and their population was allowed some growth. It wasn’t until 1966 that the first fur seal (since the 19th century) was pupped on the Farallones. Today fur seals are classified as “Vulnerable” and populations remain smaller than historic levels, from the Pribilof Islands of the Bering Sea (Alaska) all the way to their southernmost extent in the Farallon Islands of California.
On the Farallones, fur seals haul out on West End, the part of the island furthest away from the main section of the island. This season I was able to take part in the yearly fur seal survey which took place in late August. This was a treat because I was able to access this part of the island which is normally off-limits, and see some fur seals up close. It also involved a fun crossing involving a fixed rope and tethered harness across a watery channel. We counted hundreds of fur seals – much more than expected and a new record for the Farallones. They appear to be doing extremely well, and are starting to displace California sea lions from some of their traditional haul-out sites.
Harbor Seal (Phoca vitulina)
Harbor seal is an abundant and common seal species often seen throughout the region. In fact, they are the most widely distributed pinniped species, and can be found both in the Pacific and in the Atlantic, from the Arctic to temperate zones.
They are incredibly shy and vulnerable to disturbance. While we wouldn’t come across them too often, it was always a treat as their coats were incredibly variable and they looked so content hauled out. Towards the end of my stay, late summer, the females were pupping and I got to see a few young pups. The pups are covered in a silky down called inugo, and amazingly, they can swim within hours of birth.
I don’t really know what else to say about this charismatic species, except that they are undoubtedly, incredibly cute.
For over a century, human presence and exploitation seriously limited the abundance and health of pinniped populations of the Farallones. However, through the research-based conservation efforts of Point Blue and the US Fish & Wildlife Service, these populations have rebounded and are nearing historic levels.