The trip began under beautiful clear skies and with a lot of anticipation. We had not been to the Brown Booby colony on the Coronado Islands in several years. Recent reports indicated there could be several hundred boobies now roosting there, and with the extreme El Niño event, who knew what else might be there. In addition to the warm water pattern in the equatorial Pacific from the El Niño, we have an associated warm water anomaly in our area, which can cause unpredictable patterns of seabird distribution. And we certainly seemed to experience some of that today.
As we motored out through San Diego Bay, we had several ELEGANT TERNS, which are getting late now, as most of them head off to their wintering grounds in Central and South America by late October and early November. As we passed Ballast Point, a sharp observer picked out a half-dozen BLACK OYSTERCATCHERS in the cobbles along the beach, so we slowed and moved in closer for better views and photographs. As we continued on, hundreds of BRANDT's CORMORANTS were streaming out of the bay to feeding areas further offshore.
Almost as soon as we were out of the bay, we had our first BLACK-VENTED SHEARWATER and the first of many BROWN BOOBIES for the day. Several boobies put on a nice show flying around the boat as we motored out, while others were roosting on the channel buoys. Not long after, we began to encounter our first BONAPARTE's GULLS, which continued in small groups throughout the day. One of our astute passengers noted later in her photographs that she had a gull on the water she initially identified as a Bonaparte's, but her photograph showed red coloration along the base of the bill, which is more consistent with a Black-headed Gull – a rare bird for our area. Unfortunately, she only has a few photos of the bird on the water, and ideally we would like flight shots showing the underside of the primaries, which would be dark in a Black-headed Gull and light in a Bonaparte's. We are soliciting any photos of Bonaparte's-type gulls in flight from the trip to see whether we can verify the identity of this interesting gull. In the end, it could be that the reddish bill base is an artifact of exposure, with the sometimes-brownish bill base of Bonaparte's just looking a bit redder in the bright sunlight, but we may never know for sure.
We also picked up our first of four POMARINE JAEGERS for the day in the nearshore waters, and began to encounter CASSIN'S AUKLETS in pairs and small groups. The auklets were particularly uncooperative today, generally flushing and flying away before we could get very close. Nevertheless, by the end of the day everyone had gotten at least a few good views and some decent photographs. As expected, things slowed down a bit over the San Diego Trough as we headed to the 9 Mile Bank, but we still managed to pick up some NORTHERN FULMARS, with a range of light to dark morphs, and a few RED PHALAROPES. Although we had some Red-necked Phalaropes on our October trip, they have now moved on further south, making their long trek to pelagic wintering grounds off of South America.
The 9 Mile Bank was not as productive as it usually is. We only managed to pick up a few additional species, such as a single BLACK STORM-PETREL off the stern, and a distant unidentified storm-petrel off the bow.
Anticipation began to build as we headed south towards Mexican waters. We crossed the border at approximately 10:25 AM, and almost immediately encountered a BROWN BOOBY in flight. By the time we got to the booby colony, everyone was at the railing with cameras ready. In addition to 117 BROWN BOOBIES roosting on the steep southeast face of Middle Rock, there was a lone adult BLUE-FOOTED BOOBY in the midst of them all. The nearest breeding areas for Blue-footed Boobies are in the Gulf of California, and while they will move up the northwest coast of Baja California after breeding, they don't normally make it all the way to the Coronados Islands. This was definitely the highlight of the trip, but there were a number of other island surprises before we got back to San Diego County waters. We had the expected PEREGRINE FALCONS, BLACK OYSTERCATCHERS, and PELAGIC CORMORANTS, along with a WANDERING TATTLER, but were surprised to find a juvenile RED-TAILED HAWK, a NORTHERN HARRIER, OSPREY, and a hybrid AMERICAN x BLACK OYSTERCATCHER as well. There is an area of overlap in the breeding range of American and Black Oystercatchers in northern to central Baja California and hybridization is becoming a conservation concern for American Oystercatchers here. We could easily tell that this individual was a hybrid by the fact that it's black bib extended further down the chest than would be expected for a pure American, and there was quite a bit of black smudgy spotting extending onto the white belly. For the detail-oriented birder, there is a scoring system (the Jehl scale) that can be used to grade the purity of these American-Black Oystercatcher hybrids.
Sea Surface Temperature Anomaly Map – El Niño
As we headed back to the Bay, the calm conditions we had enjoyed all day became a little rougher as we headed into the swell and the wind, but it was a nice change of pace. The big surprise on the way back was a flock of 11 SNOW GEESE lifting off the water and heading northwest – not a species we typically see offshore! A few of the other highlights for the day included several HERRING GULLS, a HERRING x GLAUCOUS-WINGED GULL hybrid, and a pair of distant unidentified MURRELETS.
Although bird numbers and diversity were down a bit compared to previous November trips, it was still quite a thrill to visit the booby colony and find a Blue-footed Booby, which was a lifer for some. The El Niño is expected to continue into early 2016, so who knows what the coming year will bring in terms of unexpected seabirds. We are working on our 2016 schedule now so check back in a month or so to see what we have planned for the coming year.
Thanks to everyone who joined us on this last trip of the year, and we look forward to seeing many of you next year.
This site is owned and operated by the Buena Vista Audubon Society 2202 South Coast Highway, Oceanside, CA 92054 (c) 2007-2015 Buena Vista Audubon Society, Oceanside, California. All rights reserved. All photos copyrighted.