This is the trip report for Sunday May 21, 2017. Thirty-four passengers and seven leaders meet on a bright clear morning with a quarter moon and a beautiful sunrise.
The trip leaders were Tom Blackman, Matthew Binns, Peter Ginsburg, Paul Lehman, Guy McCaskie, Dave Povey, and Bruce Rideout. As the day broke we got all hands organized. Paul did an orientation and we cast off for the ocean. We got a nice mixture of terns on our way out with Caspian, Royal, Elegant and Forster's Terns seen. We even got good looks at a couple of Heermann's Gulls on the way down the channel. Heermann's Gulls are prototypical San Diego beach birds most of the year, but are largely absent for the late spring and early summer. They breed on islands in the Sea of Cortez, and then disperse to the northwest as far as southern Canada.
We did a slow cruise by Ballast Point, the sight of a cobble beach known historically for its rocks being used as ballast in old sailing ships. This was also the location for the Spanish Fort Guijarros (little stones), and later an early lighthouse. Today only the U.S. Coast Guard and a lone Whimbrel and Killdeer occupied the point.
The weather offshore was different than what we'd just experienced in the bay – an ominous fog bank hung just off Point Loma, and a cool breeze and swell on a fairly short interval set in. Often this is the most uncomfortable portion of the ride and so it was today. To clear the shallows and attending kelp beds, we have to proceed south for a couple of miles before turning west and taking the swell and wind wave head on. The swell interval then lengthens and one can get the feel for a steady fore and aft rise and fall, instead of the disconcerting side roll we had in the ship channel. Even before we cleared the kelp beds a Brown Booby was called out, follow by a second. Brown Booby was once quite rare here, with only a single record for California prior to 1983. Then in the 90's the number of records accelerated. Brown Boobies were seen in numbers around the Coronado Islands just below the Mexican Border, and by 2006 we were seeing boobies on most of our trips. Now we count Brown Booby as regular here and would feel slighted if we missed it. Brown Boobies have nested and raised young on the Coronado Islands each year, likely starting around the year 2000, and in recent years have traveled well north of us into Central and Northern California. Brown Booby is certainly an amazing story with the unseen changes in the ocean environment locally. We counted seventeen today, a very nice number, but certainly within the norm.
The next species seen was Black-vented Shearwater, another regular and expected local specialty. Like the Heermann's Gull, its numbers are at low point here during the breeding season. They nest on islands well below the Mexican border on the Pacific Coast of Baja. We saw the first few at distance, and that can be frustrating, but as the chummed flock of gulls behind the boat is irresistible to them, we soon got much better looks. This small fast moving shearwater is dark above and has a white breast and belly. The plumage pattern is somewhat variable, but the flight style is pretty consistent. The burst of rapid wing flaps followed by a short glide is pretty distinctive, and once keyed in on, helps separate it from other shearwaters. We had fair numbers of Black-vented Shearwaters today (24), perhaps a bit higher than one would expect for late May. Hopefully this is not a sign of problems for the Black-vents breeding this year.
Further offshore we added sightings of Sooty Shearwater. This is a dark-bellied shearwater and equally fast moving. Unfortunately they are much less likely to check out our chummed gull flock, but their numbers gave us some closer looks by chance. This is a southern hemisphere breeder, spending their winter up here during our summer. Many are in wing feather molt, so the unusual light areas on their wings correspond to uncovered feather shafts. Sooty shearwaters will complete their wing molt before returning to breeding areas off South America and New Zealand. The next species also showed no interest in our chummed gull flock, in fact they would prefer to avoid boats and gulls. These were Black Storm-Petrels. Again, looks can be frustrating and distant. Black Storm-Petrels are all dark, and although small, are actually on the larger end of the scale for a storm-petrel. The wing beat is distinctive; in straight line flight they raise their wings quite high and take a deep wing stroke downward. They may actually do short glides, almost shearwater-like. They breed locally on the Coronado Islands, and on one of the islands further to the north of us. They are common in the summer months here, at times numbering in the thousands.
The last shearwater seen today was Pink-footed Shearwater, which are most often found outside the Nine Mile Bank, only rarely closer to shore. These guys love the gull flocks and are often the photographer’s best friend. They return to the flock over and over, giving everyone great close-in looks. Sooty Shearwaters, on the other hand, often make one pass and are gone. We certainly saw plenty of Pink-foot Shearwaters today and this can be an easy species to over count. Pink-footed Shearwaters are also southern hemisphere breeders, from the islands off of Chile. Like the Sooty Shearwater, most are currently in wing molt, often giving the upper wing a patterned look.
The breeze and sea conditions made it tough to find small alcids today. Two species were seen. The best looks were at a couple of pairs of Scripps's Murrelets. This species has recently split from the old Xantus' Murrelet. This is another local specialty that breeds on nearby islands, and is a species with a rather small world population. I have seen estimates of the total number of Xantus' Murrelet, now broken into Scripps's and Guadalupe Murrelets, at no more than 10-12 thousand birds. No matter the number of each species, the total is a very small number indeed. A third and very similar species is the more southerly Craveri's Murrelet. They may in some years show up here in late spring into the summer and fall. This is a highly sought species for birders and can be difficult to get in the U.S. Interestingly, its population, although small, is actually larger than the old Xantus' complex, at 13-15 thousand total birds. Only Scripps's were found today, as would be expected. While we were looking at the first pair of Scripps's Murrelets, we had a Wilson's Warbler fly in and circle the boat at no more than arms length, even landing on my head briefly. It’s not that unusual to have migrating land birds drop down through the clouds at daybreak and find themselves out over the ocean. They then often see the boat as the only solid thing to land on. We had several land birds this morning, but this and a Yellow Warbler were the only two to approach close enough to I.D.
The only other species of alcid was Cassin's Auklet. These are dumpy, small, gray, no-necked-looking, rather plain auklets, which are terrified by the boat and the gull flock. Most flee well out of the range of a normal birder’s vision, but occasionally may allow us to approach to within a moderate distance. They are food specialists, concentrating on the tiny euphausiids we call krill. Cassin's Auklets are one of the most abundant alcids along the west coast of North America. Their population can be highly variable from point to point depending on food source abundance and availability near the surface. We saw less than 20 today, so it’s probably safe to say there are not a lot of krill available for them right now. This seems to be a down spring for Elegant Terns locally. Word is that they abandoned their nest colony in the salt works on San Diego Bay this year. We counted about 50 today, and they were seen at all distances from the beach out to the Thirty Mile Bank. Last year's May 21st trip had 1400, and nesting at the salt works was a great success that year.
We also got distant looks at two rather late Sabine's Gulls. These must be stragglers, as most Sabine's Gulls passed up the coast on their way to their arctic breeding grounds more than a month ago. Common Terns may also have moved through earlier. Their spring migration is still a bit of a puzzle. We had birds as early as February this year, so the 8 seen today may be nonbreeders or stragglers. Common Terns are not common here, but when we see them it is more often in late summer and fall. Their numbers have fallen from historic records.
This next bird could have been a trip stopper, and almost got away entirely. It was a well photographed though distant COOK'S PETREL. As happens on these long 12hr trips, the afternoons on the return are warm, the ride smoother, and with the early wake-up, all hands are a bit worn out. Some are sleeping, others getting a bite of lunch, some lost in conversation. The few actively birding are on the bow, and the wheelhouse crew is concentrating forward, so for something good to sneak through way off the stern is not a surprise. Jimmy McMorran was alert enough to see a distant flash off the stern and got a few quick shots, and then it was gone. Only when the photos were enlarged was it clear what he had. Would-a, could-a, should-a, but no way to go back by then. Every single birder on the boat would have had a county bird, some a life bird. The Cook's Petrel is a really nice bird, and we are all envious. This is only the second record for the species in San Diego County waters. This bird was about 26 nm west of La Jolla, over the outer portion of the San Diego Trough. The other record was June 13, 1997 at 16 miles. Cook's Petrel is another southern hemisphere breeder (islands off New Zealand) and is likely rare but regular in spring and early summer well offshore (>100 nm) near San Diego. Although this bird was gone before anyone else could have gotten on it, it is a reminder for all of us to call out any unusual birds we see – no one will care if it's false alarm. Then, if it is that life bird, you're a hero!
The return back to, and then down, the Nine Mile Bank was uneventful. We did get better looks at Black Storm-Petrels and even the smaller Ashy Storm-Petrel, lots of Sooties, a few Pink-foots and Black-vents, and even a few Least Terns. The best show of the day was a feeding pod of Common Dolphin south of Point Loma, which yielded a nice mix of inshore species, including Brown Pelicans, Brandt's Cormorants, Elegant Terns, and some eight Brown Boobies of all ages and sexes as a nice end-of-trip bonus. The west Mexico subspecies of Brown Booby is brewsteri; the adult males show a frosted white head, unlike males of other Brown Boobies subspecies. The adult females have a uniformly dark brown head and neck. Both were present and gave lots of photographers excellent shots. A fun finish as we headed into the harbor, with a quick look at Zuniga Jetty, and the bait docks for a few last photos of the regulars there. Sea surface temps were clearly cooler this spring. Today those temps were 62-67 degrees F.
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