The only Northern Gannet in the Pacific Basin has called the Farallon Islands his home for the past four years.
He looks a little lost here, surrounded by Pacific seabirds – Common Murres and Brandt’s Cormorants.
The only Northern Gannet in the Pacific Basin has called the Farallon Islands his home for the past four years.
He looks a little lost here, surrounded by Pacific seabirds – Common Murres and Brandt’s Cormorants.
The Western Gull (Larus occidentalis) is the”typical” large, white-headed gull of the west coast of the US. Seen at most beaches, but rarely inland (except at the Salton Sea), this is more of an obligate “sea” gull than other gulls. They breed on offshore islands during the summer, and the Farallones constitute an important breeding location for them. They are the most obvious island resident due to their numbers and their character. Here, a brilliant quote from one of California’s earliest naturalists – William Leon Dawson.
Much that is good and all that is evil has gathered itself up into the Western Gull. He is rather the handsomest of the blue-mantled Laridae, for the depth of color in the mantle, in sharp contrast with the snowy plumage of back and breast, gives him an appearance of sturdiness and quality which is not easily dispelled by subsequent knowledge of the black heart within. As a scavanger, the Western Gull is impeccable. Wielding the besom of hunger, he and his kind sweep the beaches clean and purge the water-front of all pollution. But a scavanger is not necessarily a good citizen. Call him a ghoul, rather, for the Western Gull is cruel of beak and bottomless of maw. Pity, with him, is a thing unknown; and when one of their own comrades dies, these feathered jackals fall upon him without compunction, a veritable Leichnamveranderungsgebrauchsgesellschaft. If he thus mistreats his own kind, be assured that this gull asks only two questions of any other living thing: First, ‘Am I hungry?’ (Ans., ‘Yes,’) Second, ‘Can I get away with it?’ (Ans., ‘I’ll try.’)
[…]Nothing in the life of the Farallons [sic] is more striking than the rapacity of the gulls and their determination to profit by any excitement which will frighten the peasantry.
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.
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.
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.
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…
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.
—– Written for (and cross-posted from) the excellent Point Blue Conservation Science Blog – Los Farallones —–
My internship at the Farallones involved many different fascinating studies, but one of my favorite studies were the seabird diets, as they really tie in the oceanographic aspect of marine ornithology. We are lucky to be able to live on this incredible, rugged island surrounded by the Pacific ocean and work with the birds that call it home, but sometimes it can be easy to take for granted just how strong the connection is that these birds have to the marine environment. By incorporating the feeding ecology of the seabirds, we are also considering vast topics like oceanic health, fisheries ecology, and climate change, much of which is still poorly understood. Taking part in studies that delve into this mysterious, watery realm is pretty exciting. Brandt’s cormorants also happen to be one of my favorite birds on the island – how could you not love the silky black birds that look like Muppets with long necks and giant feet, and whose eyes are a vibrant, deep turquoise?
One of the most charismatic, yet underappreciated birds on the planet has got to be the Crested Auklet (Aethia cristatella). Crested auklets are ridiculously goofy-looking birds during their summer breeding season.
Most species of seabirds are pretty unassuming in appearance, with a standard palette of blacks, greys, white, and browns, and the sexes are frequently similar. -Part of the reason for this contrast with much showier avian groups like parrots and songbirds is because of the parental investment that seabirds engage in. Most species are long-lived and only raise one or two chicks a year. In Crested Auklets, both parents engage in parental care, often sharing incubation and feeding duties – although at least one study showed that CRAU males tended to brood and defend chicks more often, while females tended to forage and bring food back for the chicks more often. This serial monogamy means that there is no pay-off for the male bird to copulate with as many females as possible, as they all already have a mate, a brood, and it takes a lot of work to care for and raise the single chick.
2013 was pretty great with Asian birds. Got back into the US just in time to start the new year, so 2014 starts with California birds and then the glories of birding the Aleutian Islands!
With a dual interest in the seemingly distantly related fields of marine biology and ornithology, seabird ecology emerges as a definitive choice of study for me personally. As the synthesis of my two favorite areas of science, it also has the potential to extend into other fascinating fields of study involving conservation biology, resources management, island ecology, biogeography, fisheries, oceanography, evolution, and behavioral ecology – all of which are topics of import on their own, but framed through the lens of seabird ecology, present expansive research opportunities.
I find myself most engaged by topics that address the interplay between components of ecological systems. In many ecosystems, seabirds play a vital role of connecting the biomass of the oceans with those on land. They act as conduits of nutrient transport, therefore playing vital roles in the ecosystems they are part of. On many oceanic islands, terrestrial life would not be sustained without the activity of nesting seabirds. Since many oceanic islands (especially in the Pacific) are volcanic in origin, they were never close enough or connected to land masses from which mammals, crawling insects, reptiles, etc could colonize. This made them blank canvases for birds who could simply fly across vast watery moats – and in so many cases, avian life dominated many remote islands and through the raw power of evolution, adapted to fill a wide variety of niches. With the lack of land predators, there were many instances where birds simply lost their ability to fly. Of course, as humans came to dominate the planet and expand across it, many islands were discovered by sea-faring groups. This was unequivocally bad news for the islands’ bird species, especially those flightless ones. Many avian species were extirpated within a short period of time after human discovery, falling as easy prey. Another important issue that came later was the introduction of other species to islands – goats, pigs, cattle, cats, mice, and especially…rats. Invasive rats have been inadvertently introduced through human activities to about 90 percent of the world’s islands. This statistic is almost unbelievable. Even more scary is the result of these invasions: they are responsible for approximately 50% of all island bird and reptile extinctions. Thus it is not surprising that Norway rats present a serious and ongoing threat to seabirds in the Aleutian Islands. They have invaded entire islands, introduced through human shipping activities. Currently there are about a dozen islands where rat populations are established, and consequently bird populations on those islands have been decimated. The first invasion event in the Aleutians was likely a Japanese shipwreck in 1780, where everyone but the rats perished. Rats are especially harmful because they breed quickly, can eat pretty much anything, and do so opportunistically – including seabirds, their chicks, and their eggs. On many islands this was catastrophic, wiping out a significant portion of crevice- and burrow-nesting seabirds like auklets, storm-petrels, and puffins during their short summer breeding season. The worst thing the rats would do is not just killing to feed, but indiscriminately killing dozens of birds and eggs in one haul.
In fact, the group of Aleutian islands immediately to the east of Buldir are called the Rat Islands because of their overwhelming domination. Buldir itself has been kept rat-free thanks to its isolation and distance from any nearby islands where rats might colonize from. Buldir sits in the middle of a shipping lane between Russia and Asia. We would frequently see massive container ships pass by on the horizon. Just from the frequency of passes, the risk for rat invasion is relatively high. Weather in the Bering Sea is notoriously challenging, and an average of two ship incidents happen a year. Rats are certainly inhabitants on almost all of these vessels, and they know when to leave a sinking ship. Fish and Wildlife appropriately has a “rat spill” team that responds to sinking ships, attempting to prevent any swimming rats from reaching shore using floating barriers. The communities on the populated Pribilof islands of St. Paul and St. George proactively maintain an island defense network against rat invasion. The native Tribes offer rat prevention kits to fishing vessels that visit harbor, and local fish processing businesses are required to have rat prevention systems in place. Rat traps are deployed and maintained in harbors and dumps – and in over 15 years, they have caught 6 rats this way, meaning that there is indeed movement of rats from ships in harbor onto the islands.
A bit of good news: the Rat Islands have been the site of a successful rat eradication campaign that resulted in the declaration of one of the islands (now re-named Hawadax, Aleut for “those two over there”) completely rat-free in 2009. This was the result of a tremendous cooperative and costly effort between the US Fish and Wildlife, The Nature Conservancy, and Island Conservation. The entire island was basically heavily treated with poisoned rat bait…and it seemed to have worked.
Human effects, both direct and indirect, are having consequences on seabird populations around the world. Few people come into direct contact with seabirds, and yet through various activities (seafood consumption, plastic use/abuse, climate change, invasive/introduced plants and animals, pollution, oil spills), most species are suffering from consequences exerted by humanity. Seabirds can seem to be so far removed from human activity that some people are baffled at even the idea of a “seabird”.