It's October....Where Are The Birds??

It has been about two weeks since our last update from the Farallones, and although a few birds have come and gone, we are still awaiting (hotly anticipating) a Fall fallout. Strong Northwesterly winds and dense fog have conspired to keep birds away from our Island, but we remain hopeful that things will pick up as September ends and October begins.

In the two weeks since our last update, a few birds have managed to find the Island, despite the strong wind and dense fog, but in far lower numbers than are expected from this time of year. For example, while we expect to see greater than 100 Yellow Warblers in a given Fall season, we have only recorded ten individual Yellow Warblers so far in the 2009 Fall Season! The same is true for most of our other typical Fall migrants: 'Western' Flycatchers, Willow Flycatchers, Warbling Vireos, Black-headed Grosbeaks, Orange-crowned Warblers, Townsend's Warblers, Wilson's Warblers and Common Yellowthroats are all way, way down from their usually abundant numbers. It's still too early to be sure if later Fall arrivals, species like Hermit Thrush, Red-breasted Nuthatch, Ruby-crowned Kinglet, and Fox, Lincoln's, White-crowned , Golden-crowned and Savannah Sparrows will make a decent showing, but we still await our first Hermit Thrush, Red-breasted Nuthatch and Lincoln's Sparrow of the Fall.

As is usual for the Fall Season, a few rare vagrants have shown up this year. Some, such as Blackpoll Warbler, Tennessee Warbler and Clay-colored Sparrow show up every fall, generally in small numbers. This Fall has also been slow for these "usual vagrants", but representatives of many of them have made an appearance. Every year we also expect a few rarer birds to show up. This year some of the highlights have included a Connecticut Warbler (the first on the Island since five appeared in 2006) on September 18th , a Brown Booby observed on seawatch on the 19th, a dark-lored White-crowned Sparrow, of either the mountain race oriantha or the eastern subspecies leucophrys was observed, and on September 27th, a minor day of arrivals, a Prairie Warbler (the first since 2005), a Bay-breasted Warbler, and a Painted Bunting, one of fewer than 15 records for the Island, were all discovered. The Painted Bunting was a very disheveled-looking individual, that when caught and banded, was aged as a second-year bird. Painted Buntings are one of the very few species of North American birds that can be aged as second-year in the fall.

However, even such exciting birds as the Connecticut Warbler and Brown Booby pale in comparison to the star of the Fall (so far!), a Brown Shrike, discovered by interns Matt Brady and Ryan Terrill on September 24th. It was eventually captured and banded. This species, a very rare stray to North America from Asia, has only occurred two times before in California, and fewer than a dozen times for North America as a whole - mostly from western Alaska, but also one record from Nova Scotia. The two prior records from California were both from the mid 1980s: the first record was of a juvenile bird, caught and banded right here on Southeast Farallon Island in late September, 1984, almost exactly 25 years ago; the second record was of a juvenile bird discovered by Oregonian birders visiting Pt Reyes in late October, 1986. That bird spent the winter at Olema Marsh, near the town of Pt Reyes Station, and was last seen in March, 1987. Unlike both of those older records, this year's bird was determined to be an adult female. Although juvenile Brown Shrikes can be confused with juvenile Northern Shrikes, adults are unmistakable. This one, with a bright rufous tail and cap, and slightly darker back, was deemed to be of the nominate subspecies, which is what all other records from North America have been attributed to.

In addition to the birds, we have had some interesting insects as well. It seemed that even in the dense fog, a few Odonates and Butterflies were able to find the Island, and on most days a few were found and identified. Although both Painted and West Coast Ladies were seen most days, the big insect highlight of the fall occurred on September 22nd, when two Western Pygmy Blue butterflies were photographed. These were the first identified on SEFI since 1998! We have also had our first Monarch of the year, as well as good numbers of Familiar Bluets, and a few Variegated Meadowhawks and Black Saddlebags. Only one Green Darner has been seen, which is normally one of the more common Dragonflies for the Island

Continuing their strong showing from the Summer, Whales have maintained a constant presence around the Island. While Humpbacks have been the most abundant species, with up to 25 individuals on some days, a few Blues have been around, too. Our resident Gray, whom we have nicknamed Dorian, has been seen just about every day. Sometimes it will come so close to the Island that we can almost imagine reaching out and touching it!

On September 19th, Jordan Casey, our Seabird Season holdover, departed the Island. After she left the Island, she visited the Monterey Bay Aquarium, where she finally got to see a Great White Shark, then headed back to the East Coast. She'll be spending the winter doing seabird work on another set of rocky islands: the Galapagos! Cassin's Auklets are cool, but can they compare with Nazca Boobies? Jordan will have to keep us posted! We were joined by Mark Dettling and Kristie Nelson, two SEFI Fall Season veterans, on September 26th. With six birders on the Island, what astounding rarities will be found?? Stay tuned to find out!

Farallon Bird and Insect Update_15-Sept-09

The weather this fall has not cooperated much to bring migrants to Southeast Farallon Island. Typically in the fall, nocturnal migrants land on the island when there is a light east to southeast wind that pushes the birds offshore. If there is cloud cover over the coast (usually a marine layer or fog), then the birds do not realize that they are over the ocean until they descend through the clouds in the morning to find food. If the ceiling is high enough so that the visibility is 5-15 miles (Pt. Reyes is the nearest shoreline at 20 miles), then the birds can see the island, but not the coast. If the ceiling is too high, then birds with sufficient energy will fly back to the coast. If the ceiling is too low, then the birds cannot find the island. The weather this fall has alternated between dense fog and gusting northwest wind. Neither allows many birds to find the island.

Although many migrant songbirds probably flew right past the island without even knowing we exist, a few hours of good weather on 9 Sept brought some nice surprises such as the Canada Warbler that we eventually caught in the Heligoland mistnet. Other interesting birds seen this day were a pair of Purple Martins flying over the lighthouse, a Baltimore Oriole seen in a cave during an area search, and a Clay-colored Sparrow in Twitville.

The fog briefly dissipated today and brought a few more birds like this juvenile Orchard Oriole.

Thankfully, some birds that arrived earlier lingered in the bad weather while others that remained may decide to overwinter. While the Farallones has had many species of shorebirds migrate to the islands, only a few species of shorebirds overwinter. The ones that do overwinter usually are ones that can utilize the extensive rocky shoreline such as Whimbrel and Wandering Tattler. During high tide, PRBO biologists conduct a shorebird survey that attempts to locate high tide roosts where large numbers of these "rocky" shorebirds congregate. Other species such as Long-billed Dowitcher turn up at the few small ponds along the water's edge or on the Marine Terrace where there is soil for foraging.

One group of birds whose numbers do not seem to be too adversely affected by the poor weather are migrant gulls. During the early part of the fall, large numbers of California Gulls migrate away from their inland breeding locations to overwinter along the Pacific Coastline or out on the open ocean. Hundreds of these gulls roost on the island each night. We have suspected that a large number of these birds originate from the relatively close Mono Lake or the burgeoning colony in South San Francisco Bay. On 8 Sept, we photographed a 2nd-year California Gull roosting on the Marine Terrace that was wearing a band. Three of the digits on the band (575) were legible. I contacted Kristie Nelson, a PRBO biologist who bands California Gulls at Mono Lake, and asked her whether it could be one of her bands. She said that they finished banding in 2008 with band number 945-57575. So it likely that the band I read was one of the 75 birds that had 945-575XX.

Frequently when we have even semi-decent weather, we see a few migrant insects such as butterflies and dragonflies. These two "ladies" are superficially similar, but if you look closely at the outer part of a forewing you'll notice that Painted Lady has two white spots along the leading edge while West Coast Lady only has one white spot. Over the last few years, Painted Ladies have been far more abundant than West Coast Lady. Although we're seeing a typical number of Painteds (n = 9) over the past 3 weeks, we've had >6 times as many West Coast Ladies as Painteds. Clearly this is a good year for West Coast Ladies!

The Fall Season Begins

August 22nd marked the start of PRBO Conservation Science's Fall Season here on Southeast Farallon Island, when focus shifts from the spring and summer breeding seabird monitoring, to the Passerine migration and Great White Shark monitoring of the fall. PRBO Biologists that arrived on the Island yesterday were Jim Tietz, Ryan Terrill, Jill Gautreaux, and Matt Brady. One Seabird intern, Jordan Casey, will be staying with us to continue seabird breeding effort monitoring.

During this transitional time, several late-nesting seabird breeders linger on the island to feed their downy chicks. While others that either already fledged their young or failed at nesting, return to socialize and perhaps prospect for next year. Tufted Puffins are particulary abundant at this time of year and we frequently see them flying closeby the lighthouse and land around crevices in small groups and then appear to discuss its potential.



Although the weather over the last two weeks has not been condusive for many migrant to find the island, we have had a smattering of West Coast migrants and a handfull of vagrants from the East Coast. For the first few days after our arrival, we experienced decent weather with high cloud cover and light northwest winds. This allowed a few of the western birds to find the island such as a Dusky Flycatcher on Aug 23rd which is actually an unusual bird to the Farallones in the fall. In fact, there are fewer than 40 records of Dusky in the fall which is odd when you consider that we have over 100 records of Least Flycatcher - a very uncommon bird along the California Coast. It is believed that most Duskies fly along the inner mountain routes and mostly avoid the coastline.






During late August and September, we typically capture large numbers of Yellow Warblers and Townsend's Warblers in our mistnets. We then colorband them so that we can better determine the number of days that each individual is present and better estimate the number of each species on the island.









In addition to these birds, a few other western birds were present such as a Rufous Hummingbird, a couple Hermit Warblers, Black-throated Gray Warbler, and both Western and Eastern Kingbirds.

On the first of September, a few more migrants found the island including a Tennessee Warbler and a Virginia's Warbler – the Tennessee is a vagrant from the northeast while the Virginia’s is a vagrant from the desert southwest.


 
















In addition to birds we also collect data on sharks, insects, bats, whales, fur seals, and anything else of interest. We’ll give some information about these other taxa in future blogs.

There Be Whales Here!

With the arrival of August, we have seen the departure of many breeding seabirds. Most Cassin’s Auklets chicks have fledged, Common Murres are no longer present, and Western Gull fledglings are beginning to take flight. The fog has lifted most days, giving us excellent visibility for whale watching. While there has been a great reduction in forage fish populations like anchovy in the Gulf of the Farallones this year, krill is abundant. This food supply has likely led to recent increases in the numbers of Humpback and Blue Whales present near the island.

Humpback Whales near Middle Farallon

When feeding conditions are good, both of these species are drawn to the Gulf in the late summer and fall from their breeding areas further south along the coast of Mexico and Central America. Humpback whales are the acrobats, leaping out of the water and slapping the surface with their immense pectoral fins. You can often see massive splashes from the breaching miles away, even without binoculars.

Humpback Whale diving behind Saddle Rock

Blue whales are the largest animals to have ever lived, and while the North Pacific Blues are not as large as their Antarctic relatives, they are still an impressive sight up close. With a blow like a fire hydrant and a 70+ ft body, there is no mistaking a blue.

 

Blue Whale in Fisherman's Bay

While blues and humpbacks have arrived relatively recently, we have seen resident gray whales at the island almost every day this spring and summer. As we have observed for the past several decades, 2-3 Gray Whales feed at the island throughout the spring and summer months. This is unusual behavior, as most grays migrate from breeding areas in Mexico to feeding areas in the Bering Sea each year. It appears that a small number of whales decide not to make the full migration, and spend their summers part way along the route.

Gray Whale off East Landing

In addition to whales, there are many species of dolphins which are present as well. Recently we have seen Risso’s Dolphins (heavily scarred by squid and each other), Pacific White Sided Dolphins (high flyers), Northern Right Whale Dolphins (look ma, no dorsal fin…), and Dall’s Porpoise (kicking up a rooster tail with their rapid swimming).

Risso's Dolphins off Southeast Farallon

Throughout PRBO’s 40 year history on the Farallones, we have documented sightings of cetaceans (whales and dolphins) as part of our long term studies on this marine ecosystem. These data have shown the recovery of several species – including Gray, Humpback, and Blue whales. We will continue to chronicle these visitors to the island, and never lose that rush of excitement upon seeing these incredible creatures.

Mist Netting for Rhinos

Often when you hear about mist netting, it brings to mind images of delicate perching birds, like warblers and thrushes, hanging in mesh before being picked out by biologists.  We do our fair share of this on the Farallones as fall brings waves of vagrant land birds out to the islands.  However, as the seabird breeding season extends into July and rhinoceros auklet chicks need feeding, our mist netting takes on a completely different character.

Rhinoceros auklets, so named for the horn they sport on their bills during the breeding season, are not actually proper auklets.  Rhinos are much more closely related to puffins, as evidenced by their larger size and fierce bite.  They also carry fish back to their chicks in the classic puffin fashion, with rows of horizontally arranged fish hanging out of their bills.  Rhinos ferry these fish back to their chicks in burrows the adults excavated at the beginning of the breeding season.  These feedings take place at twilight throughout the month of July.  This is where the mist nets come in.

Rhinoceros auklet with fish 

Right after dinner, we place a net just in front of occupied rhino burrows, lie flat on our backs, and wait quietly for the birds to hit.  And, careening through the air at speeds up to 35 miles per hour, they really do hit the net.  Rather than flitting gently into the mesh, rhinos crash into (and sometimes through) it, like feathered meteors.  Upon impact, we jump up and race to grab the bird and whatever fish it’s brought with it.  If you wait too long, your quarry is liable to escape or inflict serious damage to the net.  With their scissor bills, strong wings, and powerful heft, rhinos can shred a net in no time.  These same qualities make them a challenge to handle and they have been known to draw blood from an errant finger now and again.

Extracting a rhino from the net

An intern with a handful of rhino

Mist net post-rhino

Still, the data we collect from these uniquely intense mist netting sessions are invaluable.  All the birds that we catch in our nets are banded as part of a long term mark/recapture study to investigate survival and population trends. All birds are also weighed and measured in order to determine their sex (males are slightly larger and have a deeper bill) and overall physical condition.  Some birds have been returning to our nets since 1988! 

Rhinoceros auklet in breeding plumage with horned bill

The fish collection serves as an indication of what prey species are common in the rhino chick diet in any given breeding season.  Fish are identified to species, weighed, and measured, which helps us determine how much prey chicks are getting fed.  We can also determine which prey species are correlated with successful breeding seasons where high proportions of our followed rhino chicks fledge.  These data can also tell us a lot about the populations of the fish themselves. The species that are common in the diet tend to be those that have healthy local populations. When one species that is normally common in the diet is suddenly absent, this lets us know that the populations of those fish may be declining.

Pacific saury with bill marks

Taking measurements on fish

Diet samples with squid, Pacific saury, and myctophids

Thus far, the northern anchovy, a perennial rhino favorite, has been largely absent.  However, the plethora of Pacific saury and squid we’ve been seeing this summer bode well for the current cohort of rhino chicks.  With any luck, they’ll gain enough weight to fledge by early August and turn up throughout the Gulf of the Farallones National Marine Sanctuary and beyond this coming fall and winter.  In the meantime though, we’ll be staying up late to catch rhinos and document their diet.