Farallon Islands

Island Debrief /  by Michael Johns

I’ve been back from the birds of Southeast Farallon Island for a little over a month now, and I’m just getting around to digging through some of the photos from this season. This was my 6th year on the island, and every year I seem to take a diminishing number of shots. Still, the following series sums up the season pretty well.

We're all getting older /  by Michael Johns

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There are approximately 500 wooden boxes (shown with a rock on top in the photo) scattered around on Southeast Farallon Island that are used as nesting habitat by Cassin’s auklets, the small seabird I’m holding in the photo. These boxes have been checked every year since 1982, where pairs of auklets using each box can be identified by a uniquely numbered metal band placed on the right leg. Some of the auklets that recruit into these boxes were banded as chicks, allowing us to track age-specific patterns of behavior, reproduction, and mortality. The bird in my hand is the oldest known-age individual currently breeding in the followed nest boxes, a female based on bill depth measurements with the band # 131319997. She received this band as a fledgling when I was still in high school back in 2001, first started breeding at age 3, and has produced 16 offspring with 3 different mates so far in her long life. We discovered her incubating a fresh new egg this year in box 212 with a new mate. At age 19, she is nearing the end of her life, and time will tell whether she manages to survive this winter to breed again next year.

This figure shows all of the known-age birds breeding in the boxed population this year. Dark grey squares at the top show the hatch year of each bird (band #’s along the x-axis), gaps are years where they were not detected, and colors show the type of breeding attempt numbered by how many chicks were fledged each year. Cassin’s auklets lay a single egg per clutch (blue squares), will relay if the initial attempt fails (yellow), and occasionally double brood (lay another egg) after they fledge their first chick (pink). Auklets can recruit as early as age 3 and live to be up to 23 years old. Most birds don’t live into old age, but a few like 131319997 surpass all expectations. Click HERE for a full resolution image.

It Takes A Village /  by Michael Johns

I’ve had the great opportunity to work with an incredibly detailed long-term dataset of known-age Cassin’s auklets from the Farallones, but I think it’s important to put into perspective how much effort is required to collect these types of data. Above is a reimagined figure depicting the tenure of the many devoted people involved in maintaining a continuous time series dataset from 1967 when the field station was first established until the present. Thanks to these committed folks, we now have a unique tool for tackling a range of demographic, evolutionary, ecological, and management questions for several seabird and marine mammal species. This summer will be my 6th season on the island, which is a small drop in the bucket compared to some current and past Farallon personnel. Apologies if your names are slightly misrepresented or some of the years are missing, I still need to finish my degree after all. Full resolution figure HERE.

Catching Fish /  by Michael Johns

Sometimes a net works best when catching fish. In this case, seabird interns on Southeast Farallon Island are extracting a rhinoceros auklet from a mist net, in order to identify and measure fish the bird is bringing back to its chick. Seabirds sample the marine environment for us, and provide insights into the types of fish available around the island and within the Gulf of the Farallones National Marine Sanctuary. This particular auklet was carrying a bill load of 2 northern anchovy, a common prey item for this location.

Family of Ancient Murrelet /  by Michael Johns

Every season on Southeast Farallon Island has its share of surprises. From the residency of a northern gannet in 2012, to the invasion of hundreds of fork-tailed storm-petrels in 2017. This year it’s a family group of ancient murrelets, a species of wing-propelled diving seabirds that breeds well north of the Farallones.

Seabirds generally seek out remote predator-free islands as a refuge to lay eggs and rear chicks. This strategy ties individuals to their respective breeding colonies, limiting the maximum distance parents can travel to search for provisions for their chicks. Possibly as a means to overcome this limitation, ancient murrelets have adopted a different strategy. Rather than bringing food back to their chicks, they bring their chicks out to the food. A mere 1-3 days after hatching, persistent calls from devoted parents compel their chicks (up to 2 in a clutch) to take a plunge into the cold North Pacific ocean and paddle out to sea. These chicks, nothing more than buoyant balls of down with legs, follow their parents into the productive waters of the Pacific, slowly growing off a diet of zooplankton until they are big enough to fly and forage on their own.

What makes this sighting of a family group unique and exciting for the Farallones, is the fact that ancient murrelets predominately breed hundreds of kilometers away on the Aleutian Islands and throughout Southeast Alaska. A sighting of a chick off the island, which was likely no more than 25 days old, means it must have hatched somewhere relatively nearby - a noteworthy observation considering Washington State is the furthest south they’ve ever been confirmed to breed.

One Of Many Thousands /  by Michael Johns

A single common murre perched above tens of thousands more. Although their nesting behavior and overall appearance resembles that of a penguin, these wing-propelled diving seabirds are actually more closely related to puffins. And unlike penguins, these birds have retained their ability to fly…but just barely.

Auklet Family Tree /  by Michael Johns

Part of the basic seabird monitoring work we do on the Farallones involves tracking the reproductive history and lifespan of Cassin’s auklets that were given uniquely marked metal leg bands as chicks. Just over 400 wooden nest boxes were installed across the island in 1983, which mimic the natural burrows used by the auklets, and birds quickly started breeding in them. Over the past 35 years, each box that contained a known-age pair was checked every 5 days to note when an egg was laid, whether or not that egg hatched, and whether or not the chick reached fledgling age. Some of these chicks from known parents recruited into their own nest boxes and started breeding, resulting in multiple generations of birds all within close proximately to each other. Above is a family tree created with the kinship2 package in R, showing the largest pedigree in the known-age dataset that spans 6 generations from 1987 up until 2018. Click HERE for a higher resolution version.

Bill Load of Fish /  by Michael Johns

This animation represents the total number of prey delivered by common murre parents to awaiting chicks during a 14-hour diet watch. Each red dot depicts a single breeding site in one of our followed study plots on Southeast Farallon Island. Circles appear when a fish is delivered, and intensify in color as more fish are brought in throughout the day. Common murres deliver a single item after each foraging trip, the size and species of which are identified by Point Blue field scientists as birds fly into their respective sites. On this particular day in 2016, foraging parents were bringing in predominately anchovy, followed by juvenile rockfish and a mix of less common items such as squid, smelt, flatfish, and juvenile salmon.

Seabird Sizes /  by Michael Johns

This figure depicts the relative sizes of seabirds that breed on the Farallon Islands. Larger circles mean more massive birds, smaller circles less massive. Species in the order Pelecaniformes, colored in shades of blue, are among the largest birds that breed on the island. The Ashy Storm-petrel in yellow, although a part of the order Procellariiformes which includes some of the largest seabirds like albatrosses, is small enough to fit inside the palm of your hand. The diverse order Charadriiformes in shades of red includes all of the gulls and auks, the latter of which contains all of the wing-propelled pursuit divers like puffins, murres, guillemots, and auklets. Mass information was gathered from the Sibley guide to birds. This plot was made almost entirely in R, with a few minor tweaks made in Photoshop. A full size image can be downloaded HERE.

Make It An Animation /  by Michael Johns

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Sometimes, an animated figure tells the story better than a static one. We have been tracking the non-breeding movement patterns of Cassin’s auklets from Southeast Farallon Island since 2015, in an effort to understand the environmental drivers of their winter dispersal. Part of the work I’m doing for my PhD is linking the movements of auklets to remotely sensed conditions relevant to their foraging ecology, in the case of this animation chlorophyll-a concentration (left) and sea surface temperature (right) from November 2017 through January 2018. Chlorophyll, the photosynthetically active molecule that gives plants, algae, and certain types of bacteria their green pigment, is used as a measure of the concentration of phytoplankton. Krill, which comprises much of the Cassin's auklet diet, graze on phytoplankton, so it’s reasonable to assume productive areas with high concentrations of chlorophyll-a likely contain greater densities of krill than areas of low chlorophyll-a. Similarly, lower sea surface temperatures are generally associated with nutrient rich cold water from depth, which help spark blooms of phytoplankton. One hypothesis, visualized with this animation, is that Cassin’s auklets are searching for colder regions of higher productivity during the winter months. The next step is to test this hypothesis with a series of competing models, to see which best explains the patterns observed in the data.

Visualizing Long-term Data /  by Michael Johns

Point Blue Conservation Science has amassed an impressive long-term dataset on the breeding histories of known-age Cassin's auklets on Southeast Farallon Island. These data are visualized in the figure above. The dedication to maintaining and checking 400+ artificial nest boxes every 5-days for the past 34 years has allowed researchers to reveal some unique patterns in the life history of this small seabird. For example, Cassin's auklets are the only member of the taxonomic Alcid family to attempt two complete broods in a single breeding season, known as double brooding. In a recent study published in the journal Proceedings of the Royal Society B, my colleagues and I used these data to examine how double brooding impacts future reproductive potential and survival for birds that attempt such a behavior multiple times over the course of their lives. It turns out that so called "repeat double brooders" represent a subset of high quality individuals that can offset the short-term costs of increased reproductive effort, living well into old age and producing more offspring than birds that never double brood. Visit the publisher’s website by clicking HERE. 

Listers /  by Michael Johns

The Farallon Islands are uniquely situated for people interested in the hobby of finding and identifying birds, otherwise known as "birding". The cluster of jagged rocks are located just far enough offshore to provide a stable platform for spotting rare pelagic species like the Cook's petrel, and close enough to the mainland to catch vagrant song birds and other terrestrial species lost in the fog at sea. Over the course of 50 years of research out on the Farallones, some biologists and staff have been keeping a detailed list of all of the different bird species they've encountered while out on the island, a record known as "The Faralist". This figure is a graphical interpretation of that list, modified from R code for a similar graphic depicting the number of days spent on island by various people over the years. Collectively, a total of 429 different species have been seen from the Farallones; not bad for a small collection of guano-covered rocks with only 3 trees.

Download a high resolution file of this figure HERE.  

Final Chicks of the Season /  by Michael Johns

Ashy storm-petrels are endemic to the California Current System, which means their entire population occurs in the offshore waters of the California coast. Half of the world's estimated 10,000 individuals breed on Southeast Farallon Island, their chattery calls a regular sound after the sun goes down in the summer. They are amazing swallow-sized seabirds that spend much of their lives exposed to harsh winds and rough seas, thriving on small planktonic items they pluck from the productive surface waters of the Pacific. These enigmatic relatives of the albatrosses have a more prolonged occupation on the Farallones compared to the other breeding seabird species, extending chick provisioning efforts well into early October. They are generally the last chicks to hatch on the island, small grey puff balls that can be viewed on occasion in shallow crevices if you look hard enough. 

Rabbit Cave /  by Michael Johns

We monitor the breeding population of Rhinoceros auklets on the Farallones by checking artificial wooden nest boxes distributed across the island. These boxes are visited on a regular basis to note which ones contain an active breeding pair, whether those pairs are successful at hatching an egg, and ultimately how many pairs end up fledging a chick; giving us an estimate of the annual breeding success for this species. In addition to the nest boxes, we also monitor breeding activity in Rabbit Cave, a large vestige of the islands geologic past that acts as a kind of massive burrow for Rhinoceros auklets. The entrance to Rabbit Cave starts out as a narrow crawl space that opens up into a cavernous amphitheatre at the back. 

Landscape of a Year /  by Michael Johns

Animals tend to be fairly predictable in their reproductive timing and migration patterns. The figure above depicts a series of density curves, with peaks and troughs corresponding to the average timing of key biological events for a select number of marine species that are monitored on or from Southeast Farallon Island.

Pinnipeds, a taxonomic group that includes seals and sea lions, are found hauled out on the island year round, with peak pupping events occurring in the summer. Northern fur seals, which have made an astounding recovery on the Farallones following the days of the Russian Fur Trade, remain at sea for several months of the year and are only seen in force from summer to late fall. Whales are also visible from the island year round. Gray whale numbers peak in January as they migrate south to their breeding grounds off Baja California Mexico, and again in March during a northward migration back to their feeding grounds in Alaska. Humpback and blue whales are most abundant in the productive summer months, where they are seen gorging themselves on krill and schooling fish. For seabirds, breeding occurs only in the summer months, with the exception of the ashy storm-petrel which extends chick rearing well into October. Three distinct peaks represent the timing of egg laying, hatching, and chick fledging. 

The study of seasonal life-history patterns is called phenology, and it can tell us a lot about the stability of a system. As I mentioned, animals tend to be fairly predictable in their phenology. Individuals cue in on environment and biological signals, so shifts in the timing of reproduction or migration can indicate changes in environmental condition, food availability, or the health of a population. For species found on the Farallones, the major cause for concern in the face of a warming ocean is the availability of key prey items, namely krill, which sustain the rich biodiversity in this region. A mismatch between the timing of krill and the timing of reproduction for seabirds can lead to major declines in breeding success, and subsequent declines in population numbers. 

Data courtesy of a partnership between Point Blue Conservation Science and the USFWS. The plot was created in R with the ggplot2 and ggridges packages. 

Sei Whales Off The Farallones /  by Michael Johns

In addition to daily opportunistic sightings, we conduct standard 1-hour whale watches from atop Lighthouse Hill to document the timing and abundance of Cetaceans around the Farallon Islands. These data are useful in particular for showing where whales are in relation to shipping lanes leading into San Francisco Bay, to better inform mitigation measures aimed at reducing the number of ship strikes.

On one particular whale watch, during an exceptionally calm day, I came across a feeding flock of 6 black-footed albatross and several dozen pink-footed shearwaters. I considered the possibility that this flock was associated with killer whales, since albatross have been known to scavenge on orca kills, and killer whales had been reported in recent days just south of us in Monterey Bay. Sure enough, after watching for a few minutes a tall black dorsal fin came into view, followed by two smaller fins. A pod of transient killer whales that were feeding on some unknown pinniped at the surface. After radioing the sighting to the rest of the crew, everyone made it up to the lighthouse for a look before they eventually departed to the west. 

After the killer whales had left we decided to keep looking around for other sightings. Within minutes a blue whale surfaced right next to the East Landing mooring ball, in water probably half as deep as the length of the animal itself. As if that wasn't good enough, someone pointed out a small pod of whales swimming toward the island. They were all dark baleen whales with a visible blow, six of them traveling in tight formation towards an islet we call Sugar Loaf. Initially, I assumed perhaps it was a group of minke whales, clumping together in response to a pod of their natural predators nearby. The shape of their rostrums, size, behavior, and blow were all wrong though, and as they got closer we couldn't see an signs of white patches indicative of minkes on their pec fins. They were too small to be fin or blue whales, too big to be minkes, and definitely not a toothed whale. The only other obvious possibility for this part of the world is the sei whale, a species of rorqual found in temperate waters worldwide, but generally seen much further offshore and rarely sighted off California. 

To put this sighting into context, only 17 sei whales have ever been seen on the Farallones since 1987, and generally the sightings consisted of a solitary individual. Not only did this group contain a Farallon record breaking 6 animals, but they swam close enough to the island for us to get excellent looks for a prolonged period of time, and even photos of the event (of which my favorite is of a western gull pondering whether it can eat one of the whales). Truly a rare and amazing sight. 

Photos taken through Point Blue Conservation Science | USFWS

Relative Size /  by Michael Johns

Probably the most important question in the conservation work that we do, and the most popular question people have about the Farallones, is the population size of the various seabird species on the island. The answer, such as roughly 250,000 murres, 20,000 auklets, and 500 puffins, may not be fully appreciated when taken at face value. The figure above is an attempt to put these numbers into context by representing each population as a collection of boxes, where the area of each box is scaled in proportion to the other boxes. With this visualization, you can see just how abundant Common Murres are in relation to Pigeon Guillemots or Tufted Puffins. With continued monitoring and management, hopefully all of these boxes will continue to grow in size.

Data courtesy of a partnership between Point Blue Conservation Science and the USFWS. The plot is called a "Treemap", created in R with the ggplot2 and treemapify packages.