Changing of the Guard: Week One of the Fall Season

August 23, 2015

   Breeding seabird numbers are declining on Southeast Farallon Island (SEFI) as fledgling cormorants, guillemots, and puffins head to sea to ply their trades.  Western Gull chicks are still numerous, but many have fledged and total numbers are slowly decreasing.  As seabirds depart, landbird migrants are arriving in greater numbers as we move into peak migration periods for many regular migrants and rarer species from eastern North America and (we hope) further afield.

An adult Pigeon Guillemot at a nest cavity–some young are still being fed and many fledglings are visible around the island.  Photograph by Jim Tietz

   Saturday the 15th of August saw the annual transition from the summer seabird to the fall migration crew. The sailing vessel Another Girl, captained by Jim Bewley, picked up Pete Warzybok, Liz Kain, and Daniel Johnston and headed for the mainland, while Eva Gruber remained to finish remaining seabird studies and assist the fall team for the next three weeks.  Jim Tietz, Boo Curry, and Adam Searcy arrived to begin songbird migration studies and other fall research.  They were joined by Colter Cook and Jonathan Shore, who worked on invasive plant removal and then essential maintenance duties after Cook’s departure and the arrival of Ed Van Til on Outer Limits on 17 Aug.

Cassin’s Auklet chick–a face that any mother should love.  Photograph by Eva Gruber

   Migration on the island was slow for the first several days, thankfully, as the fall crew was busy reviewing East and North Landing boat launch procedures, safety and awareness training, and other essential tasks required to get the fall research program up and running.  Many thanks to Jonathan and Ed who provided much help and support until their departure on 20 August aboard the U.S. Coast Guard Cutter Sockeye.

   Immediately noted by the arriving crew were the number of California sea lions on the island.  During a survey conducted on 20 August, Jim and Boo counted over 5,000 on SEFI and just over 300 on West End Island, their usual territory.  Why have they moved?  We have no idea!  Jim also counted over 800 northern fur seals including 300+ pups, an excellent count documenting the continued population increase of this species that is still recovering from a long history of fur hunting. Tufted Puffins are another species that is increasing with ~100 active potential nest sites documented this year and an impressive tally this week of 190 individuals representing the record high count for California (to the best of our knowledge).

One of our omnipresent sea lion companions.  Photograph by Adam Searcy

A Tufted Puffin from Lighthouse Hill.  Photograph by Adam Searcy

Food for Western Gull chicks became the fate for many Pigeon Guillemots and other alcids as the ocean warmed up late in the summer and became less productive. Thankfully most chicks fledged before this aquatic heat wave began.  Photograph by Jim Tietz

   Some of the first land bird migrants encountered upon the fall crew’s arrival were two Eurasian Collared-Doves, a Blue-gray Gnatcatcher, Western Tanager, and Bullock’s Oriole.  The Oriole stayed on the island until at least the 20th while the Gnatcatcher and Tanager departed within two days. The doves were joined by another pair, and an island record high-count of 20 Mourning Doves was counted the beginning of week two.  One of the resident Peregrine Falcons immediately went for the dove flock, so their stay on the island might be a brief one.

These two Eurasian Collared-Doves have been hanging out for a week–one with typical plumage and the other showing some abnormally white (leucistic) plumage. Photograph by Jim Tietz

   Migration began to pick up on the 17th through the 21st with decent numbers of newly arrived migrants and good diversity.  Birds seen included a Rufous/Allen’s Hummingbird, Hermit, Black-throated Gray, MacGillavray’s, Townsend’s, Wilson’s, Yellow, and Orange-crowned Warblers, Least, Pacific-slope, and Willow Flycatchers, Western Kingbird, Ash-throated Flycatcher, an early Black Phoebe, Western Tanager, Bullock’s Oriole, Northern Mockingbird, Pacific Wren, House Wren, Blue Grosbeak, Lazuli
Bunting, and Red-breasted Nuthatch, to name a few.

An Ash-throated Flycatcher at the lighthouse.  Photograph by Jim Tietz.

Rufous/Allen’s Hummingbird (most likely the former) investigating the MLB Memorial Mallow Preserve.  Photograph by Adam Searcy

A lovely Hermit Warbler at the Lighthouse.  Photographed by Jim Tietz

This rotund Pacific Wren was found beneath the water tank.  Photograph by Jim Tietz

One of three Red-breasted Nuthatches seen this week.  Photograph by Jim Tietz

Black-throated Gray Warbler at the Lighthouse.  Photograph by Jim Tietz

   Also continuing for its third year is the famous Northern Gannet–joined by a Blue-footed Booby and as many as 10 Brown Boobies.  The presence of the latter species may be explained by the continuing warm water ‘blob’ that is persisting for its second year in the Eastern Pacific.  Numbers of Brown Boobies are also very high on islands to the south with nearly 20 having been recorded off Santa Barbara Island in early July.

   The unquestionable highlight of this migrant wave on 21 August was an Upland Sandpiper found walking about on the marine terrace near dusk, representing the 7th record for SEFI and the first since 2002 and the 31st record of this species for California. Adam Searcy was conducting an area search for migrants, when he and the sandpiper stumbled into one another.

Upland or Bartramian Sandpiper on the marine terrace.  Photograph by Adam Searcy.

   Thankfully, the rest of the crew was nearby (after chasing a misidentified Least Sandpiper) on the cart path, and everyone was able to see this stately bird. Upland Sandpipers breed broadly through the plains states of the US and Canada and into the Northeastern states as well as northwestern Canada and eastern Alaska. Their normal migratory pathway is through the Midwest and eastern states heading south to wintering grounds in central and southern South America, only rarely straying west to be detected in California.

   Weather forecasts for the next few days are good for migration, and we hope to have many more sightings to report in the near future. To better keep up with what we’re seeing each day, please check out our eBird checklists and the Farallonia Flickr account.

Happy birding,
The Fall Crew