Gifts from the Easterlies

April 21, 2022

Spring weather on the Farallones is deceptive. While the mainland begins to wake up from the dormant stage of winter, the temperature on the islands becomes cooler. The trademark northwesterly winds of spring that creates rich upwelling zones within the California Current rips through the lonesome rock, sometimes reaching gusts up to 40 knots. After a week of work in chilling conditions, we were given a sweet, warm reprieve in the form of an easterly wind.

The day started when Island Biologist Amanda Spears reported from her weather survey that a heatwave from the mainland combined with an eastern wind was blowing hot air our way. It felt like a summer’s morning, when you can feel the night’s residual coolness quickly evaporating with each hour. It was 8 am and already 16.5 degrees Celsius. Research Assistant Tatjana Beck announced from her walk down the cart path, “I heard lots of chipping and tweeting by the carp shop”.

Amanda’s eyes lit up, “Oh?”

Readers, what we see in this moment, is a birder trying to keep their cool. But we know, the chase is on.

Our morning work as research assistants consists of monitoring Brandt’s Cormorants at their breeding colonies on the northwest side of the island. From covert blinds, we resight returning known-age cormorants by their color and metal leg bands. We have Wi-Fi on the island, but watching the trials and tribulations of cormorant courtship and nest building has been our own version of “Love Island”.

The research assistants arrived back at the PRBO house to find Amanda posted up by the house tree armed with the house camera and 10×42 binoculars.

Warbler town. Standing by the house tree, we were treated to a display of warblers, sparrows, and other welcomed songbirds.

Before we get into the birds spotted, let’s discuss how weather conditions caused this migration event:

We could simply say that the songbird fallout could be attributed to the alignment of favorable weather conditions and time of year. According to “Rare Birds of North America” by Steve Howell, Ian Lewington, and Will Russell, “Most species prefer to migrate in clear conditions and with a light tailwind.” When birds migrating over land encounter adverse conditions, like headwinds or rain, they stop traveling and land. However, songbirds over open ocean don’t have that option. In the case of spring flights across the Gulf of Mexico, birds that have drifted offshore may reorient to land. In our case, the morning of April 7th had only 10 miles of visibility and a light easterly wind of 8 knots. Warblers, migrating back north after their winter spent in Central America, most likely got caught in the offshore drift, and with poor visibility of the mainland while they were over open ocean, made their way to the island to recuperate. We double checked that night with the Cornell Lab run bird forecast project, BirdCast, and saw that the 7th was the peak of songbird migration so far for the month of April!

Back to birds. Amanda, revealing her passerine-study origins, listed off species with a casual ease. That day we counted 10 warbler species, four sparrow species, a vireo, kinglet, thrush, and flycatcher; along with many shorebirds, seabirds and gulls spotted in the good weather. Highlights included a Nashville warbler, hermit warbler, Wilson’s warblers, and many black-throated gray warblers.  That day was a rare experience to get a prolonged look at similar warbler species up close. Both sexes of Audubon’s warblers and myrtle warblers foraged beside each other, showing their distinctions clearly like the book of Sibley come to life.

During the afternoon, a male rufous hummingbird even made an appearance! We were mesmerized by the hummingbird’s small quick form, displaying brilliant flashes of its orange breeding plumage as it flitted between the mallow plants. The research assistants took full advantage of the day, spending time in between surveys looking for songbirds and savoring the warm weather. One research assistant even wore shorts! It was glorious.

Of course, a respite is but a short period of rest, and as quickly as the easterlies had come, they had left, along with most of the songbirds. While there were stray Audubon’s and myrtle warblers that remained for a few days after, it was best that our visitors had made a quick exit. For the next two days after, the northwesterly winds picked up their tyrannical bluster at a consistent 20 knots.

By Sarayu Ramnath

 

Follow Farallon Islands on Ebird for a daily bird count!

4/7/22

Surf Scoter x 27

Red-breasted Merganser x 1

Eared Grebe x 80

Rufous Hummingbird x 1

Whimbrel x 2

Black Turnstone x 3

Thayer’s Gull x 1

Glaucous-winged Gull x 10

Pacific Loon x 5

Brown Booby x 2

Northern Gannet x 1

Brown Pelican x 4

Peregrine Falcon x 3

“Western” Flycatcher x 1

Warbling Vireo x 1

Ruby-crowned Kinglet x 2

Hermit Thrush x 1

Chipping Sparrow x 1

“Sooty” Fox Sparrow x 1

“Oregon” Dark-eyed Junco x 2

White-crowned Sparrow x 16

Lincoln’s Sparrow x 5

Orange-crowned Warbler x 1

Nashville Warbler x 1

Common Yellowthroat x3

Myrtle Warbler x 5

“Audubon’s” Warbler x 11

Black-throated Gray Warbler x 10

Townsend’s Warbler x 5

Hermit Warbler x 1

Wilson’s Warbler x 2