By Terry Hunefeld
(San Diego) Saturday’s Buena Vista Audubon Society pelagic trip to the Thirty Mile Bank re-found the storm-petrel flocks seen there the previous two weekends. Once again we located the swarm just over the “Lister-County-Line” in L.A. county by following Least and Black Storm-Petrels to the mother lode. Saturday’s flock was larger, estimated at 10,000 total birds, with Least once again outnumbering Blacks 70/30. Also seen were Sabine’s Gull, Common Tern, 19 individuals of three species of jaeger and Xantus’s Murrelet.
We motored out of San Diego harbor at 6:00 a.m. before sunrise. As soon as we emerged from the harbor we encountered Black-vented Shearwaters (750 for the day – a ten-fold increase over last weekend). Other Shearwaters in San Diego included Pink-footed and Sooty. A flock of Common Terns flew by, headed south. We saw our first 8 Pom and Parasitic Jaegers between the harbor and the Nine Mile Bank.
Black, Least and Ashy Storm-Petrels were seen in both San Diego and Los Angeles Counties including 15 Leasts at or near the Nine Mile Bank.
Crossing the San Diego Trough between the Nine and Thirty Mile Banks we had dozens of Long-beaked Common Dolphins come to Grande and ride the shock wave of the bow. Arriving at the Thirty Mile Bank we saw a late-migrating Long-tailed Jaeger near the L.A. county line. Storm-petrels were more plentiful now, and 95% of them (including a few San Diego Ashies) were flying north, so we followed them about two miles “over the line” into “L.A. county” and found a swarm of storm-petrels estimated to be 10,000 of Least and Black, with Leasts outnumbering Blacks by 70/30.
Shortly after Dave Povey laid an oil, beef fat & popcorn slick, a white rumped storm-petrel came racing up the slick, snatched a piece beef fat and went flew directly away, never to be seen again, despite nearly two hours searching.
It wasn’t the Wedge-rumped we saw the weekend before because the Wedge-rumped was fresh-plumaged, this bird was in heavy wing and tail molt. In the photo it appears to be a Leach’s which is usually easily diagnosable in the field by flight style, but this bird had so much wing molt it was flying differently. Photos, while not 100% conclusive, lean toward the Guadalupe breeding Townsend’s subspecies of Leach’s (socorroensis) rather than the nominate (northern) Leach’s.
We alternately motored and drifted through the swarm of storm-petrels as it spit into multiple rafts, forming, dispersing, then reforming like an early Windows screensaver. When we were downwind of a raft, their musky smell was powerful – compared by some to “Grandma’s musty basement.” The call “Sabine’s Gull!” went up as our only one of the day flew over a raft.
Crossing back into San Diego County we motored along the Thirty Mile getting good looks at a Fin Whale and flushing a Xantus’s Murrelet. We spotted a distant Elephant Seal. Upon entering San Diego harbor we checked the Zuniga Jetty for shorebirds finding a Black and an American Oystercatcher.
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