Tuesday, October 13, 2015

Zalophus Invade the Farallones

Before the early 1800's the Farallon Islands were home to hundreds of thousands of Northern Fur Seals (Callorhinus ursinus). The Northern Fur Seal's coat boasts an impressive 9,000 hairs per square inch. Their precious pelts attracted Russian and Bostonian fur traders, who ruthlessly hunted them until none were left on the islands. Little is known about the population sizes of other species of pinnipeds (seals and sea-lions) during that time. But after Northern Fur Seals were extirpated from the Farallones, the California Sea-Lion, AKA Zalophus californianus, has likely been the most abundant pinniped on the island.

The relatively thin fur of Zalophus coats were not as sought after as Northern Fur Seal coats.

Over the last several years during pinniped censuses we typically count approximately 3-4 thousand Zalophus between August and November. When the Point Blue Fall crew arrived on the Farallones this August, we found that the number of Zalophus using the island was over 8 thousand! 

This huge increase has caused the Sea-Lions to push further up onto the island than usual. Most of the Marine Terrace, where we normally walk transects looking for migrant landbirds and shorebirds, is now occupied by about 5,000 barking Sea-Lions. Because of their tendency to stampede straight into the ocean whenever they spot a human, we have to tread very lightly and avoid certain portions of the island so that we don't cause any unnecessary disturbance.

We are now observing some of the highest counts of Zalophus ever recorded on the Farallones since we began the census in 1970.

They have even disrupted communications between our weather station and house! Usually, we can monitor the wind speed and direction from the comfort of the living room, but the connection was lost when the herds of Zalophus started crawling around the weather station. Most likely, a wire has been ripped loose from the base of the tower by all of the jostling furry bodies.

Part of the Marine Terrace Zalophus Horde next to our weather station (seen in the upper left corner).

View from the front steps of our house.

Aerial view of the Marine Terrace herds. Usually the Zalophus stay down near the shoreline, but here you can see hundreds of them hauled out all around the helo pad.

This year, California has seen an enormous number of Sea-Lions being stranded on its beaches. Wildlife rehabilitation centers have been overrun with sick and starving Sea-Lions that have washed up and been brought in for treatment. The phenomenon is extensive enough that it has been picked up by many mainstream news agencies:

High numbers of strandings are thought to be an indicator of an impending El Niño, as hungry and starving individuals flee the overly warm and food poor waters to the south. During the last event in 1998, California saw 2,500 malnourished Zalophus wash ashore, and what followed was the most extreme El Niño event ever recorded.

We may be in store for many more Zalophus invasions in the coming years. Global climate change is predicted to increase the frequency and intensity of El Niño events, as explained by a study discussed in this article:

A stranded Zalophus pup and concerned human bystanders on a Port Hueneme beach in Southern CA.
A marked individual from San Miguel Island, which likely made its way here to the Farallones in search of food. We have been resighting a lot of marked Zalophus from San Miguel this year.
So, in the meantime, as we sit here surrounded by these noisy, furry harbingers of El Niño, you can enjoy some Zalophus portraiture from around Southeast Farallon Island:

Zalophus pup near the Sea-Lion Cove blind.

A seemingly smiling adult male at North Landing.

An adult male at East Landing, showing a bit of Zalophus drool.

Friday, October 09, 2015

Mono Lake Gulls on the Farallones

Most falls since 2001 I have undertaken a migration of sorts: one that takes me from Mono Lake, in eastern California where I live, to Southeast Farallon Island. This island has an in incredible draw for me – the birds, the wildlife, the magic, I keep coming back to satisfy my soul. It seems an unusual route to travel – from Sagebrush, Pinyon Pines and Clark’s Nutcrackers to crashing waves, ocean breeze, sharks and seabirds. Surprisingly, I am not alone on this voyage. Each year, large numbers of California Gulls make the same exact journey.

California Gulls hold a special place in my heart – and not just because of this commonality. Since 2005 I have run Point Blue’s Mono Lake California Gull research project, which measures the colony’s annual population size and chick production. Initiated in 1983, this is one of Point Blue’s longest continually run research projects. Back then, the future of the Mono Lake gull colony was perilously threatened by human-caused water diversions. These diversions lowered the lake level to a point where the gulls’ formally safe nesting islands became connected to the mainland, making them vulnerable to Coyotes and other land-based predators. Fortunately, due to the hard work of dedicated scientists and others, in 1994 the lake was court-mandated to be managed, through reductions in water diversions, to rise to a target surface elevation of 6392’. This elevation would keep the gull nesting areas protected and the lake ecology thriving.

Mono Lake is a terminal lake, meaning water entering through its tributary creeks can only exit via evaporation. Over time the lake became hyper-saline, much like Utah’s Great Salt Lake. In summer and fall, its briny waters contain alkali flies, trillions of brine shrimp, and the lake is home to one of the largest breeding colonies of California Gulls in the world.   

Breeding California Gulls at Mono Lake. Note the snow-capped volcanoes in the back-ground (the Mono Craters). Some of the gulls from Mono Lake migrate to Southeast Farallon Island. Photo by Justin Hite
But in fall, the California Gulls leave Mono Lake and cross the Sierra Nevada in one high-altitude flight. Most winter coastally, often traveling relatively far offshore to forage. On pelagic sea-birding trips you may continue to see California Gulls at distances further out at sea than their Western or Glaucous-winged cousins. The flexibility of California Gulls to transition from foraging on alkali flies and brine shrimp on Mono’s shores - to riding oceanic waves with shearwaters, keying in to pelagic food resources, and following oceanic upwellings in their winter pelagic transiency, I find absolutely astonishing. This Great Basin to coastal transition is especially impressive for the juveniles; as many have only gained independence from their parents and learned to forage independently at Mono Lake just a few weeks before migrating to the coast and the Farallon Islands, where they must learn a whole new set of foraging and survival skills.

California Gull chicks at Mono Lake about to be banded in temporary corrals. The structure in the background is a fake half volcano from a 1952 movie set that now serves as basecamp for Point Blue gull banding volunteers. Photo by Teague Scott
The fact that many Mono Lake California Gulls use the Farallones became apparent starting in 2009, when we began color-banding the Mono Lake gull chicks. On a single day that fall,  I had a high-count of 6 color-banded Mono Lake gulls! That translates into almost 1% of all the California Gull juveniles produced at Mono Lake that year roosting on a few acres of little Southeast Farallon Island that day!

Each year since, fall biologists and interns have detected color-banded Mono Lake gulls, although numbers fluctuate greatly each year. Considering that we only band 3 -4 % of Mono Lake’s gull chicks each year, these detections make it clear that the Gulf of the Farallones and its surrounding waters are an important stop-over for a significant proportion of Mono Lake’s California Gulls. 

Fall California Gull data from SEFI show some really interesting trends. Starting about 10 years ago, shortly after a standardized protocol for counting migrant gulls was initiated in 2006 (they were counted opportunistically before), annual numbers of migrant California Gulls visiting Southeast Farallon climbed tremendously. Their numbers peaked in 2008, and then dropped back to where they were before the climb. It’s difficult to interpret what caused this, but I suspect it relates to local food abundance. When feeding is hot around the Farallon Islands, the California Gulls will come, if it’s better elsewhere, they will move elsewhere. Color band resights and band recoveries of Mono Lake California Gulls on fall migration have also been difficult to interpret as well: some birds have been resighted north as far as Oregon, while others go south (southern California or Baja) – even within the same fall. Much is unknown about California Gull fall and winter movement patterns: where they go, how much they wander, what they eat, and their habitat requirements. But, hands-down, the single place where by far the largest number of Mono Lake color-banded gulls have been resighted is right here on Southeast Farallon.

Color banded juvenile California Gulls banded at Mono Lake, photographed on Southeast Farallon. The red coded bands are great – easy to detect, frequently reported by observers, but also very expensive. At Mono Lake, some chicks get the red, coded bands (as many as we can afford) that allow us to quantify and track individuals, but most get a simple color band, like the green one below. Photos Jim Tietz

Hopefully fall biologists and interns continue to document many color-banded Mono Lake gulls on the Farallones. Yet drought and climate change are bringing back the same predation threat caused by low lake levels we thought was resolved following the State Water Board’s 1994 decision to “save” Mono Lake. Despite reduced water diversions, it is currently about 14 vertical feet below the targeted 6392’, and dropping. Just one more dry winter could result in large parts of the gull colony becoming accessible to coyotes, which would be devastating. This was not supposed to happen. But data and models used to generate allowable water diversion rates back then did not include climate science as we know it today. There are measures in place to reduce or eliminate water diversions from Mono Lake if it continues to drop, but there’s a chance these rules are not fully adequate to protect the gulls in a hot, dry climate.  Hopefully we don’t need to resort to desperate measures to protect Mono Lake gulls, like erecting an electric fence to prevent coyotes from crossing a land bridge if the lake continues dropping. And hopefully this drought ends and Mono Lake starts a steady climb in surface elevation. But if not, science may need to step in again, as it did decades ago, to reevaluate how best to keep Mono Lake and its gulls protected.
The fog is lifting, I think I’ll take the scope out and check the roosting gulls in hopes of finding a color banded friend from Mono Lake.  

Photo from Mono Lake gull banding basecamp, overlooking Mono Lake, Paoha Island, and the Sierra Nevada. Islands of Mono Lake are home to one of the largest breeding colonies of California Gulls in the world. Photo by Ryan Spaulding
Mono Lake never ceases to amaze me. Many of the California Gulls that visit SEFI in fall were hatched here. Photo by Robert Di Paolo.
Posted by Kristie Nelson, Mono Lake California Gull Project Manager

Thursday, October 08, 2015

24th Annual Farallonathon

We just completed our week long 24th annual Farallonathon and despite our relatively slow September, we made a respectable final score compared to the other years. For all of those who are new to this, the Farallonathon is the Southeast Farallon Island's version of Point Blue's Bird-a-thon fundraiser. The Farallonathon was started in 1992 by Peter Pyle in order to highlight the uniqueness of the island and the diversity of the species it attracts. That being said, we do things slightly differently: our count lasts an entire week instead of just 24 hours, and we count all species including mammals, dragonflies, butterflies, sharks, and of course, birds. Each species gets one point, unless it needs to be reviewed by the California Bird Records Committee (CBRC), then it gets five points. For first island records of a species we are awarded ten points, and for each shark attack we get an additional five points.

Day 1 - We started off with typical Fall weather—fairly clear skies, visibility almost to the mainland, a light wind out of the NW. We had our usual 3 species of sulids: Northern Gannet, Brown Booby (15 individuals!), and a Blue-footed Booby for a total of 15 points, since they're all CBRC birds. On the evening sea watch, two of our birders saw a Manx Shearwater fly by, yet another CBRC bird.

A few other noteworthy birds were the two Dickcissels, one of which we banded, 

 a Sharp-shinned Hawk,

 a Magnolia Warbler,

and two Rock Pigeons, which may seem rather mundane but this introduced species rarely shows up on SEFI in the fall.

There were also a host of other birds that we see here more commonly such as Lesser Goldfinches, Fox Sparrows, Golden-crowned Sparrows, Black Phoebes, an Anna's Hummingbird, Audubon's Warblers, Western Wood-Pewee and several Burrowing Owls.

We also had our only non-marine mammal for the entire week, a red bat which had been hanging around for a few days in a bush (see previous blog entry) and a Black Saddlebags. All this gave us 90 points for our first day!

Day 2 – The weather stayed the same, but we had a few more birds find their way to the island. Two Eared Grebes were seen floating near the island early in the morning and a Black-footed Albatross graced us with it's presence (though far off) on an afternoon seawatch. On land we had a few new species including three Swainson's Thrushes, a Chestnut-sided Warbler, a Clay-colored Sparrow and a Lapland Longspur.

We also saw two shark attacks from the lighthouse giving us an extra ten points, bringing our total to 110.

Day 3 – The winds continued to be light from the northwest with visibility to the mainland. We had a few different species of warblers show up as well as two more shark attacks. For warblers, we found Townsend's, Western Palm, Blackpoll, a Common Yellowthroat and banded a Nashville.

In addition, we found a Say's Phoebe, a Pine Siskin and a Northern Harrier that was spotted flying over the terrace. From the lighthouse we spotted two Blue Whales and a pod of 30 Common Dolphins adding two more points for a total of 133.

Day 4 – Today was a bit slower than the rest due mostly to the wind picking up to 15kts (17mph). The only points we scored were for the 8 new birds that turned up: Pacific Loon, American Wigeon and South Polar Skua on sea watches and a Mourning Dove, Northern Flickers (yellow-shafted and intergrade), two Western Meadowlarks and two Brewer's Blackbirds on land. With the additional eight points we were up to 141 at the end of day 4.

Day 5 – With a gale in the forecast for later in the day and our attention focused on a boat landing in the morning, we did not expect to find many birds or other species around the island. The winds peaked around 40kts (46 mph) and the swell got up to 15 feet or more. That didn't discourage us from finding a few new birds. A Grasshopper Sparrow was found taking shelter from the wind in a rock pile and a Short-eared Owl was found doing the same under a bush of tree mallow (Lavatera arborea) and later in a Pigeon Guillemot crevice.

During the evening seawatch one of our interns spotted a Red-breasted Merganser flying close past the island which is one of the earliest records for this species.

Day 6 – The winds calmed down to almost nothing from the night before and began to shift direction from the usual NW to a more favorable migrant bird forecast of S to SW. The morning started off with a Swamp Sparrow at our bird bath outside the living room window

which inspired us to start searching immediately. Early in the day we heard a Wood Peewee call that was not quite right for Western. We caught it and measured it out as an Eastern and upon release it started making the perfect Eastern Wood Peewee call making it a five point CBRC bird.

A group of 16 Elegant Terns were heard and then seen foraging off East Landing for the majority of the day; a Belted Kingfisher was found over at North Landing; and a Cackling Goose made it's way into Garbage Gulch.

All that plus a shark sighting and two new dragonflies (a variegated meadowhawk and a 12-spotted skimmer)  put our total at 171 points on our second to last day.

Day 7 – The weather forecast predicted the wind to continue out of the south, and for a high overcast (optimal migration conditions for the Farallones), so all of us  prepared for a big wave of birds to arrive. Although the mega-wave did not materialize, we did have a few new arrivals. Highlights for the day included the Brewer's Sparrow we found in one of our mist nets,

a Flesh-footed Shearwater flyby, two Parasitic Jaegers, the first Mew Gull of the season two Farallon Arboreal Salamanders found under a maintenance panel, and a single Painted Lady bringing our total for the week to 179 points.

We had an exciting and eclectic mix of birds this year and a good amount of shark action (4 sightings and 4 attacks) which really helped our score. For a little bit of reference we finished just above the 174 point average this year, putting us in 10th place overall since the beginning in 1992. The highest scoring year was 2001 with 240 points and the lowest was 2008 with only 129 points.

If you enjoy reading our blog and would like to contribute money to our Farallonathon to support current and future research projects, please click on the link to contribute: