Hello Seabirders, this is the Sept. 25, 2016 Buena Vista Audubon pelagic trip report aboard the Grande. We had forty-one passengers and 4 leaders today. This trip’s leaders were Peter Ginsburg, Jimmy McMorran, Justyn Stahl, and myself. We did a quick orientation and Capt. James did a safety talk and we were underway. The first stop was at the bait docks for the usual cormorants, pelicans, herons, egrets, and gulls. The next stop, Ballast Point, caused us to back down to take a better look at four Black Oystercatchers loafing there. Always a nice bird near the southern extreme of its range. We cruised down the buoy line but came up dry on our search for a Brown Booby. That species has become a local specialty in recent years. This summer things have changed and it's been tougher to count on that species. In fact today we would not come up with a Brown Booby until our return trip in the evening, and those were an adult female on these same buoys, and one other Brown Booby on a distant buoy further up the channel. We did get a nice adult Parasitic Jaeger showing it's aerial ability by an extended chase of an Elegant Tern. Lots of nice photos with the broad side of Point Loma as a backdrop. We did have a second jaeger called out back in the glare in the same area.
Offshore the birds of note were good numbers of small flocks of Red-necked Phalaropes. These birds attracted to the break and scum lines formed by the outgoing tides. Easy to tell were those lines are with phalaropes around as they often sit right along them. The outer edge of the Nine Mile Bank held most of the Black-vented Shearwaters seen today. Maybe a little further offshore than we'd expect this normally inshore species. No shortage of food out here, and most of the Black-vented Shearwaters here appeared to be full. A few even having trouble taking the air to flee the approaching boat. I saw more than one disgorge its food to lighten the load. I think all the photogs got the fill of Black-vents here. Black-vented Shearwater is our regular shearwater, present most of the year, and breeding on a few islands (mostly one) a short three hundred miles to our south. Here on the outer edge of the Nine Mile Bank we came on a pod of Common Dolphin, nothing unusual about that, but a short distance away was a dead Common Dolphin that had been bitten in half. The bite line just behind the abdominal cavity and the entire tail stalk was gone. I don't know whether the bite was postmortem or while the animal was alive, but it was certainly a very large bite mark!
We worked our way up the bank from one raft of Black-vents to the next. We did pick up a lone Pink-footed Shearwater or two here and there. That very similar-looking shearwater to the Black-vents is larger, has a bi-colored bill, pink legs and feet, and a slower more relaxed flight style. Pink-footed Shearwaters are southern hemisphere breeders, but relatively common in our summer here. Locally their numbers are well down this year – odd as forage is as abundant as any year I'd ever seen. Perhaps they are just more widely scattered elsewhere in their non-breeding range, or the particular forage (mostly Northern Anchovy) is not suitable in some way. Near the north end of the Nine Mile Bank we found several hundred Black Storm-Petrels; not sure whether they were attempting to raft up, but they scattered as we came into the area. Then the call came in of a white-rumped storm-petrel among them. It had a short winged look, with a fluttery fight, so we felt we had something good. Photos showed a short square-ish tail with the bright white wrapping under the tail, and feet sticking out behind the tip of the tail – a Wilson's Storm-Petrel – a rare bird off the California coast, although somewhat regular off the northern and central coast. They are relatively few records here, so local San Diego county birders were happy. My guess is that most of the birders onboard were hoping for the very similar and recently split Townsend's Storm-Petrel. Formerly that bird was regarded as a race of Leach's Storm-Petrel. Townsend's have the same stubby-winged fluttery flight, mostly but not always a bright white rump (and the white doesn't wrap under the tail), the tail is a little longer, and the legs do not extend beyond the tip of the tail. So far in our limited experience with Townsend's Storm-Petrels they are found well offshore here, mostly out in the areas outside San Clemente Island and further west. My best guess is that in our area they would be best expected over and around the Thirty-Mile Bank.
The Thirty Mile Bank did turn up a small raft of storm-petrels – mostly Black Storm-Petrels, but a small number of Least Storm-Petrels were mixed in. Captain James found this raft the day before, so today and we drove right to it. Unfortunately, the raft was not terribly cooperative and scattered on our approach. Past experience shows that the Least Storm-Petrels are the first to disappear as these rafts split and reform, so we stopped and put out an oil slick then pulled away a short distance. That got us a little action, with maybe 15-20 Blacks and one lone Least Strom-Petrel, for decent but somewhat distant looks. We did swing back through the remaining raft a couple more times, but little by little the Least Storm-Petrels faded from the scene. Our trip down the Thirty-Mile Bank was punctuated by a sudden stop as a pair of murrelets flushed ahead of the boat. Not great looks, and photos could not positively confirm Craveri's Murrelets. I talked to a few observers on the bow and some were certain that's what they'd seen. One passenger had even seen a second pair just before we'd flushed these two. Craveri's Murrelet is certainly the likely candidate, but one can't exclude the possibility of Guadalupe Murrelets.
The return to The Nine Mile Bank crossed a good-sized area of ripped-loose floating kelp. The captain thought this was from the recent tropical storm that came up the Baja coast. We did find a few Red Phalaropes and Common Terns scattered here. We discussed the lack of some expected but missed species when first a Pomarine Jaeger came in behind the boat, then a little later a Sabine's Gull, then, as I mentioned at the top of this report, the two Brown Boobies on the San Diego Bay Buoys. Talk about last minute pulled-out-of-the hat additions to an otherwise slow day in species numbers! Bright sun with some haze, winds light from the east early switching to 3-10kts from the west later; 2-4 ft. swell; warm sea surface temps 67-70 degrees F.
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