Boobies, the Gannet, and other Farallon Highlights

September 4, 2017

The fall crew, who, “adorned in black or the latest fashion, listen to alternative rock from their observational posts”(Pyle- “The Farallon Islands: Sentinels of the Golden Gate”), have migrated their way out to Southeast Farallon Island for another roaring season of wildlife surveys. During the fall season, the main focus is on landbird migration, but volunteer interns, with their fearless leader Jim Tietz, will also be monitoring other migrants including sharks, pinnipeds, cetaceans, invertebrates, and bats.
On the boat out to the island, in the vicinity of the Sausalito harbor on the 19th of August, fellow intern Zach Mikalonis and I spotted an interesting bird flashing by along the port side: a massive, white seabird with black flight feathers. We ran down to the lower deck from the wheelhouse to get a better view and saw that it had a black face “mask” and a bright orange bill, the distinguishing field mark revealing it to be none other than a Nazca Booby! This species has been seen only a handful of times in California, and this was the first recorded individual this far north. The crew was elated and watched as it made several close passes by the boat near the Golden Gate and disappear into the bay towards San Francisco. Nazca Boobies breed in the eastern Pacific, as far south as Peru and as far north as central mainland Mexico. These warm water birds have been seen in California now six times since the first record in 2013, and the closely related Masked Booby (also seen in the Bay Area two weeks prior to this Nazca Booby and also a tropical breeder) has also been seen in California more in recent years. These species are closely related (formerly considered one species) and distinguished in the field by the bill color and tail coloration (Nazca have white at the base of the central tail feathers). Could the changing frequency of occurrence of these species be an indication of changing climate conditions?

Boobies and Gannets are in the family Sulidae, and occur in relatively low numbers in California. They are quite large, streamlined seabirds with massive bills that they use to hunt small fish and are primarily found in warm-water regions. The Blue-footed Booby and Brown Booby, two species that occur on the island with some regularity, both breed in the tropical Pacific with their closest breeding grounds off the coast of Baja and in the Gulf of California. Both of these species have a long history of occurring in California, with first records going back to the mid-late 1900s. The famous Northern Gannet was first seen on the Farallones in 2012, and has hung around off and on since. This was the first Northern Gannet seen in the Pacific Ocean let alone on this small island! This species breeds mostly in the North Atlantic, so this particular bird travelled a long way from home to join us. With one record of Masked booby from 1994, the Island has currently recorded five species of sulids, and we have high hopes for the Nazca to make its way over to make it six!
Upon arrival to the island, good conditions brought a fun wave of migrant landbirds, giving the first-timers on the island (like me) an incredible first few days. After getting lifted off the ocean and dropped onto shore by a crane, a wild experience in itself, we made our way up the cart path towards the houses and were immediately greeted by many landbirds. An adult male American Redstart flashed by in black and red to make way for the likes of Yellow, Hermit, Townsend’s, Black-throated Gray, and Wilson’s Warblers. Among the warblers, many other species were drawn to the few trees on the island, like vireos, orioles, finches, and flycatchers. Northern-rough Winged and Tree Swallows flew overhead and Lark and Chipping Sparrows were busily searching the terrace for food. All the while the Western Gulls are yelling and California Sea Lions are basking in the sun on the lower terrace. Most of the landbirds we see here are stopping at the island during their long journeys south, with the objective of eating as much as they can and getting some rest for the next leg of the voyage. Some are off course, like Tennessee Warbler, Northern Waterthrush, and Lark Bunting spotted during our first days, and some are just passing through, like the yellow, Townsend’s, Wilson’s, and Hermit Warblers. Not many places can you spot a bright male American Redstart, far from home, foraging among the deafening cacophony of Western Gulls and California Sea Lions. One quickly learns that anything is possible on this wild forgotten oasis, where many biological worlds collide. Never is there a day that is the same as the ones before it.

During our second day on the island, we were lucky enough to witness an early-season shark attack offshore, a highlight that many enjoyed observing! That evening, while scanning the waters off of East Landing, Jim spotted a very odd-looking loon. It was bulky and black-backed with extensive white on the face and breast. Due to the distance of the bird, we hoped to find it again when it happened to make its way closer to the island. We saw it a few more times always at quite a distance, until a week later Jim and Zack ventured out on the boat to get a better look at it. After reviewing photos, we determined it to be a Yellow-billed Loon! With a slightly upturned clearly dull-yellow and relatively bulky bill, whitish facial markings including around the eye and dusky coloration on the top of the head and down the nape, this bird appeared to be in first summer plumage. This is only the second record for the island, the first being in 1997. This young bird is molting heavily and has very limited flight feathers meaning that its current mode of transportation is reduced to swimming- no wonder we have been seeing it nearly every day in a similar spot!
The second record for Yellow-billed Loon for the island! Photo by Jim Tietz/Point Blue
After a few good days of weather the winds changed to the Northwest, which brought less than ideal conditions for several days. While unfortunate for bird arrivals, it allowed the crew to really settle in, study, and get nets prepared for the next wave of migrants!