Hello Sea Birders, this is the trip report for the August 21, 2016 Buena Vista Audubon Pelagic trip on the Grande. Forty-two birders and 5 leaders meet at the Point Loma Sportfishing Landing, and the place was as crazy hectic as a fishing landing can ever be. We were all quite happy to board Grande and get away from dock and all the craziness there. Captain James McDaniels gave a quick safety talk and I did a brief orientation to birding offshore as we motored down the channel. Leaders were Peter Ginsburg, Jimmy McMorran, Gary Nunn, Bruce Rideout, and me, Dave Povey.
We did leave a few birds in our wake, such as an Osprey, a Caspian Tern, a few Mallards and the like. We headed straight to the bait dock area, as there had been a photo passed around of an albino cormorant there. The bait docks held the usual pelicans, cormorants, egrets, herons, gulls and the like, but no albino cormorant. We next headed to Ballast Point, passing the submarine base. Then the call went out: the albino cormorant was on the security fence, among the other Brandt’s Cormorants roosting there. We stopped and got photos of the very odd creature. Likely a full albino, with not only white feathers but a pink bill, odd eye color, and light colored legs. Nice find. Our thanks for the heads up from the birder who took the photo last week.
We then moved down the line of channel buoys to the open sea. I’d hoped to find a Brown Booby on one or more of the buoys, but all were empty today. We did have an inside-the-Point Black-vented Shearwater come through our chummed gull flock. Black-vented Shearwater is an inshore species, but usually outside the bay channel. Turns out Black-vented Shearwater was the most abundant species of seabird on the day – hundreds on the Nine Mile Bank, dozens over the San Diego Trough, and even a few equally out-of-place Black-vents on the Thirty Mile Bank. Then as we approached the San Diego “whistle” buoy, a Brown Booby did come in from behind, made a pass at the gulls, and sailed down the right side of the boat to have all hands scrambling to have a look at this speedster.
Offshore we found conditions a little tough. The NOAA weather forecast had said we’d face a steep wind wave and they were right. Not a big swell, not even much wind early, just that uncomfortable quick roll and snap that even a big stable boat like Grande feels. It took all of us awhile to get the pattern down, and as usual the worst was right around the shallows of the harbor mouth. That never seemed fair to my thinking.
We proceeded southwest toward the Mexican border and the inner edge of the Nine Mile Bank. The bank is neither nine miles out nor nine miles long, but on nautical charts the shallowest contour (100 fathoms) is exactly nine nautical miles long, and the inner edge is very close to nine nautical miles out (8.75 nm or so). So your guess about the origin of the name is as good as mine. By the way, a fathom is 6 ft. and a nautical mile is about 1.12 statute miles.
Regardless of its name, correct or otherwise, we found birds as we approached the Nine Mile Bank, and in good numbers. Pink-footed Shearwaters, a few Sooty Shearwaters, and lots of Black-vented Shearwaters, including a fair number in bright fresh plumaged. I take these to be young birds of the year, as most of the others were well worn and vaguely dirty looking. After all, they are a burrow nester, on islands some 230 nm to our south. We also had a few Black Storm-Petrels in this area. They often seem to shift inshore in the dark and move offshore as daylight arrives. We also picked a few Common Terns out of the numerous Elegant Terns. An Ashy Storm-Petrel here was a surprise, as were two Leach’s Storm-Petrels. These species are much more likely to be seen farther offshore, so these were much closer to shore than we normal expect. Perhaps this was due to a week of 20 kt west winds over these waters. Ashy Storm-Petrels are smaller than the more numerous Black Storm-Petrels, and shorter-winged, longer-tailed, and lighter overall in coloration. They also have a shallow rapid wing beat.
Leach’s Storm Petrels here are often dark-rumped, or show some smudgy white on the sides of the rump. These are our local breeders of the chapmani subspecies. These birds were not separated out as a species from nominate Leach’s Storm-Petrels in the recent A.O.U. split that removed Townsend’s and Ainley’s Storm-Petrels from the Leach’s complex. Chapman’s Leach’s have the same bounding erratic flight of nominate Leach’s, a deeply forked tail, often a pale rump or a few light feathers in the rump if well seen, and occasionally a nearly completely white rump. All three species nest on the local Islas Coronados (Coronado Islands), just across the border in Mexico. Black Storm-Petrels breed there in the thousands, Chapman’s Leach’s in the hundreds, and Ashy no more than a few dozen. All the island-breeding species seem to have benefited from the removal of feral cats from those and other islands off western Mexico.
We then picked up Brown Booby number two, which is also now a local breeder on the Coronados. The Nine Mile Bank also gave us the first of very few Cassin’s Auklets. This ubiquitous small acid is almost always expected, rarely cooperative for close study, and a specialist in its prey, choosing krill (or euphausiids, a tiny shrimp like creature) as its primary food. There is one other creature here that specializes in krill – the Blue Whale. Both Cassin’s Auklets and Blue Whales have been scarce this summer, so the best guess is that their food source has been scarce as well.
Another small alcid was a target species for many of the passengers: Craveri’s Murrelet, a Mexican breeder seen here in some years and absent or very hard to get in other years. This has been a fairly good summer for Craveri’s. Unfortunately, the sea surface conditions today were not helping us find them. We stumbled on a few and got fleeting glimpses from the bow of quickly departing pairs. Then we got lucky when one pair flew a short distance and splashed back down. When we approached the spot where they’d landed, we came in from upwind, a bird’s preferred direction for takeoff, so they dove instead. Then as luck would have it, they popped up right next to the boat. One bird sitting on the water drifted down the side of the boat only 50 ft. away – perfect! Couldn’t have asked for better. The sun and glare were behind us. This confused bird was busy looking for its partner. Lots of photos, and everyone got as good a look as we could have hoped for considering the sea conditions.
Craveri’s Murrelets breed far down the Baja Peninsula and in the Sea of Cortez. Like some other western Mexico species, they disperse out to sea to the northwest after breeding each year – some years far enough to reach our area, other years as far up the coast as Monterey Bay. But as previously mentioned, some years they are missed on this side of the border altogether. The world’s population of Craveri’s Murrelets is actually larger than the population of the Xantus’s Murrelets complex, now split into Guadalupe and Scripps’s Murrelets, which also disperse to the northwest of their breeding areas. Scripps’s Murrelets breed off northern Baja California, Mexico, and off Southern California, and are common here in the spring. Guadalupe Murrelets breed along the central Pacific coast of Baja California and are the toughest “regular” seabird species to get off California. Their dispersal area is usually well offshore, where few pelagic birding trips venture.
We left the Nine Mile Bank behind and headed for the Thirty Mile Bank. Crossing the San Diego Trough we got an escort of Common Dolphins for part of the way. The Thirty Mile Bank was pretty quiet. We did pick up Brown Booby number 3, and for a short time we had a nice mix of Chapman’s Leach’s Storm-Petrels. Some observers were excited by the few white-rumped Leach’s in hopes of getting the newly split Townsend’s Storm-Petrel. Townsend’s are easily mistaken for a Wilson’s Storm-Petrel, but are smaller, darker, more stubby-winged, have less fork in the tail, a bright white rump patch that does not wrap under the tail, and shorter legs, so the feet don’t extend beyond the tip of the tail. They are best identified by photo, but Townsend’s does have a distantly different “feel”. Anyway, looking through many photos, nothing could be definitively separated out as a for-sure Townsend’s Storm-Petrel. This species is a breeder on a couple of islets off Guadalupe Island, Mexico.
We turned south east to return to the Nine Mile Bank. The north end of the bank certainly had more life than the waters to the west – enough that we stopped and put out an oil slick. We did get a Black Storm-Petrel and yet another Leach’s Storm-Petrel to come in, but our persistent gull flock keep other stormies a away. We did add to the Craveri’s Murrelet count here by two and had our 4th and last Brown Booby on the day.
So an interesting day. Not the best sea conditions, but manageable. Maybe a little disappointing in numbers of species, with the absence of any hint of a Least Storm-Petrel among the negatives, but with good looks at most species and quite a few lifers for many of the participants.
Species list for the day
(* species seen only in San Diego Bay):
Mallard*
Western Grebe*
Pink-footed Shearwater
Sooty Shearwater
Black-vented Shearwater
Leach’s Storm-Petrel
Ashy Storm-Petrel
Black Storm-Petrel
Brown Booby
Brandt’s Cormorant
Double-crested Cormorant
Brown Pelican
Great Blue Heron*
Great Egret*
Snowy Egret*
Osprey*
Red-necked Phalarope
Craveri’s Murrelet
Cassin’s Auklet
Heermann’s Gull
Western Gull
Caspian Tern*
Common Tern
Forster’s Tern*
Royal Tern*
Elegant Tern
Rock Pigeon*
Barn Swallow*
Marine Mammals:
Common Dolphin
California Sea Lion
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