A Visit to “Booby Island”

 

When I first moved to Goleta in 2000, boobies of any species were barely annual in coastal southern California. Starting around 2013, that situation began to change and significant numbers of Cocos (formerly the brewsteri race of Brown Booby) began to occur on Sutil Rock, off Santa Barbara Island. These subsequently began to breed along with odd pairs of Blue-footed Booby. A period of warm water also greatly increased records of Masked, Nazca and Red-footed Boobies with the result that sometimes four or five species of booby might be seen in a single boat trip and all five have been observed roosting on Sutil Rock.

Since the booby colony represented a significant detour from the preferred routes of pelagic birding trips out of Ventura harbor, we recently started running some dedicated trips out to Santa Barbara Island. Since Santa Barbara Island is over 40 miles offshore, the journey out and back is in itself quite good for pelagic bird species, providing the optimalroute is taken. This route is along the eastern side of the deepwater Santa Cruz Basin, where upwellings attract pelagic bird species and are particularly good for storm-petrels.

On the morning of August 7, we set out on an Island Packers boat from Ventura Harbor. The crossing of the Santa Barbara Channel to Santa Cruz Island was blighted by fog and not much was visible. On clearing the passage between Anacapa and Santa Cruz Islands, visibility began to improve as we headed out along the drop-off along the edge of the basin. Grigory Heaton kindly provided the photos for this blog entry.

Storm-petrel raft

"White-rumped" Leach's Storm-petrel

After a slow start with just a couple of Ashy Storm-Petrels and some Sooty and Pink-footed Shearwaters, the numbers increased as headed into deeper waters with well over 100 Ashy Storm-Petrels with smaller numbers of Black and Leach’s Storm-Petrels, the latter featuring both white-rumped and dark-rumped (Chapman’s) birds. We enjoyed great looks at a cooperative pair of Scripps’s Murrelets. These breed locally on both Santa Barbara and Anacapa Islands but have often departed northwards by this time of year.

Scripps's Murrelet

A lone adult Sabine’s Gull was a reminder that migrants were arriving from more distant breeding areas and careful surveillance of the flocks of Sooty and Pink-footed Shearwaters, from New Zealand and Chile respectively, was rewarded with a Buller’s Shearwater. This New Zealand breeding species is rather uncommon in southern California waters. A female Cocos Booby on a kelp patty gave us a taste of what was to come at the booby colony.

Buller's Shearwater in mixed shearwater flock

As we turned towards Santa Barbara Island, we continued to see a few more storm-petrels and encountered a pair of Craveri’s Murrelets. This species is a close relative of Scripps’s Murrelets and breeds mainly in the Gulf of California in Mexico. After breeding during late winter and early spring, some move northwards along the Pacific Coast and reach California. In recent years, Craveri’s Murrelets have become increasingly common in this area and in August and September double digit counts have become almost the norm. However, this was to be the only pair we encountered on this trip. It will be interesting to see if more will be around in September.

Craveri's Murrelet

Arriving at Sutil Rock, we were delighted to see a ‘black-and-white’ booby perching quite low on the rock. As we approached closer, we could see the bill was a green-tinged yellow, indicating an adult Masked. Turning out attention to the Cocos Boobies higher up on the rock, we estimated about 70 or more birds, including several downy-covered young. Careful scanning produced several fly-by views of a Blue-footed Booby. With one brief exception, it unfortunately kept landing out of sight on top of the rock and several participants were unable to see the bird, even though we spent almost an hour at the rock.

Masked Booby

It is a standing joke that, for reasons unknown, there is a tendency to switch off on the return leg of a pelagic, resulting in fewer sightings. Fortunately, enough of us were paying attention to find a Least Storm-Petrel in one of the storm-petrel rafts encountered during the return. Given the number of shearwaters present during the trip, we had been surprised by the lack of any South Polar Skuas but our persistence was finally rewarded as one flew ahead of the boat and started harassing a Pink-footed Shearwater.

The return crossing of the Santa Barbara Channel has much better visibility and we encountered a large concentration of many thousands of Sooty Shearwaters near the entrance to Ventura Harbor. Such numbers close to shore are often present on the California coast north of Point Conception, where the waters are colder, but are not expected off Ventura or the south coast of Santa Barbara County.