Luke Passey has seen 4500 Black-vented Shearwaters
Sighting
Observation Details: (we estimated another 4500 Black-vented Shearwaters in at least two large flocks seen during our trip across the channel, with at least three leucistic birds photographed among the many birds in these flocks)
Checklist Comments: This report represents the eighth in a set of nine lists for the fall pelagic trip from Dana Point Harbor out to Crespi Knoll and the waters of the Catalina Channel northwest toward Catalina Island, from which we cut back east across the Lausen Sea Mount on our return to Dana Point. This trip, sponsored by the Sea and Sage Audubon Society, had as the leaders Jon Dunn, Tom Benson, Curtis Marantz, Brittany O'Connor, and Robert McNab, and our captain Brittany Loust on the R/V Sea Explorer out of the Ocean Institute. The seventh, and last, offshore leg of the trip took us from the Lausen Sea Mount, beginning after we descended to the floor of the channel 19¾ kilometers west-southwest of Dana Point (33° 23' 18" N, 117° 54' 30" W), back to the waters just off the mouth of the harbor, ending 1.7 kilometers southwest of the tip of the outer breakwater (33° 26' 41" N, 117° 42' 21" W). This leg took us east-northeast about 20 kilometers along a slightly meandering path across the deeper water of the channel in waters that ranged mostly 570-660 meters in depth until we reached the escarpment, at which the inshore waters quickly became rather shallow. This leg of the trip was dominated by moderate numbers of gulls in the wake and large flocks of mostly Black-vented Shearwaters, but also moderate numbers of Pink-footed Shearwaters and one Sooty Shearwater. We also saw two more phalaropes, multiple jaegers (with several each Pomarine and Parasitic), moderate numbers of Western Gulls, more Heermann's Gulls than we had been seeing, several more California Gulls, and one last Sabine's Gull, along with one each Forster's and Elegant Terns. We also began seeing again Brandt's Cormorants and Brown Pelicans, with the latter present in moderate numbers during this period. Associated with the shearwater flocks were two Humpback Whales, one Fin Whale, and a pod of about 100 feeding Common Dolphins. Despite our carefully checking the large flocks of shearwaters, we were unable to find anything truly unexpected. The eBird app on Marantz’s phone tracked our total distance at 20.74 kilometers, which is a relatively accurate, one-way distance despite some meandering. It was partly cloudy, with a 30% cover of high clouds throughout this period, seemingly light winds, and a swell of 1-2 feet, apparently from the southwest, and a surface that ranged from rippled at the beginning of this leg to rather choppy by the time we reached the harbor. Weather data taken from the NOAA website for buoy data from the San Pedro South waverider buoy, located at 33° 34' 33" N, 118° 10' 53" W, and thus approximately 33 kilometers northwest of where we began this leg of the tip, represented during this period a wave height of 0.6-0.7 meters [= 2.0-2.3 feet] with a dominant period of 13-14 seconds from the south to the southwest, and an average period ranging 8.0-9.3 seconds; water temperature during this period dropped from 21.4º C to 20.9º C [= 70.5-69.6º F]. Data from this same period from the Oceanside Offshore waverider buoy, located at 33° 10' 40" N, 117° 28' 20" W, and thus about 37 kilometers southeast of where we ended this leg of the trip, represented a wave height ranging 0.7 meters [= 2.3 feet] with a dominant period of 14-15 seconds from the south-southwest, and an average period ranging 9.4-10.0 seconds; water temperature during this period ranged 21.4-21.6º C [= 70.5-70.9º F]. 1:50-3:15 pm. Humpback Whale - 2 (two whales seen by some during this period were identified as Humpback Whales); Fin Whale - 1 (others also reported another Fin Whale during this period); Common Dolphin - 100 (the whales and shearwater flocks were associated with another large pod of an estimated 100 dolphins). The track for the day is shown below, with the yellow pins denoting the locations where we began each new list, and the cyan pins showing the locations of the more interesting species seen. We traveled along this path in a clockwise direction. <a href="https://www.flickr.com/photos/cmarantz/53258123857/in/dateposted-public/" title="GPS track for Dana Point pelagic trip - 7 Oct 2023"><img src="https://live.staticflickr.com/65535/53258123857_fd6423326b_o.jpg" alt="GPS track for Dana Point pelagic trip - 7 Oct 2023" /></a>
Protocol: eBird - Traveling Count
Duration (minutes): 85
Number of Observers: 42
Distance Traveled (km): 20.74
Black-vented Shearwater
07 Oct 2023 - 1:50pm
United States