Farallon Institute Newsletter - Fall 2024

Around The Office

FI Intern Erendira Ceballos spent the summer season participating in the University of California Davis - Bodega Marine Lab weekly public tours. She set up a station as a part of the tour and talked to visitors about seabirds and how they interact with their environment. Often people don’t realize that an animal like a seabird can be used to measure changes in the ocean. The ocean is so vast and complex, but understanding seabirds can give us a glimpse of that complicated world. People enjoy realizing that something that seems simple, like a seabird, can tell us so many things about ocean health. This Fall newsletter describes some of the ways we study seabirds in California, so please read below. Additionally, see this page for more information about the Bodega Marine Lab public tours. 

State of the Ocean — California

As we move into the fall, we are reflecting on how cool of a summer it was here in Northern and Central California. This is in part due to the strong upwelling we experienced throughout the summer. Upwelling, when deep cold water is brought to the surface, causes the cooler, tempered weather conditions near the coast. It’s also what creates the famous fog of San Francisco! Ocean water temperature anomalies (temperature different from the average) shows upwelling reflected as the cold, blue water near the coast (Figure 1). Offshore water conditions generally heat up through the summer and into the fall, but the offshore anomaly temperatures for August this year shows that conditions are actually quite a bit warmer than average. These anomaly maps are calculated from daily water temperatures, so each month reflects how warm or cold the temperatures are relative to that specific month. 

The ocean conditions we are currently experiencing are more of the “norm”. We officially exited El Niño conditions in May 2024 (source: NOAA). Even though this most recent El Nino was relatively muted in the nearshore California Coastal Ecosystem, it did still have dramatic effects on marine species (see article on Alcatraz seabird colony monitoring). Though we are currently in a neutral El Niño-Southern Oscillation (ENSO) phase, we are still predicted to enter La Niña conditions within the next few months. Interestingly, the forecast models for ENSO have us returning to neutral conditions by this time next year though, so as of now it looks like it will be a quick and mild La Niña. As for what that means in terms of winter precipitation, we will have to see what the climate models suggest. Given the normalcy of the ocean conditions this summer and fall, it is likely that the climate will revert back to traditional La Niña conditions, meaning less than average rain and snow for California with much more in the Pacific Northwest, but time will tell!

Map of the Eastern Pacific Ocean with anomalous sea surface temperature (SST) from June, July, and August 2024 (L–R). Red values indicate higher than average SST and blue values are below average. Daily anomalies were calculated relative to a 1971–2000 climatology from the NOAA OI SST V2 High Resolution Dataset.

Alcatraz Island marks 30 years of seabird colony monitoring

2024 marked the 30th consecutive year of monitoring for the seabird breeding colony on Alcatraz Island! During that time, under the protection of the National Park Service (NPS), the island has come to host up to ten species of seabirds and waterbirds, in addition to a pair of peregrine falcons that settled on the island in 2020. The seabird colony began with 181 pairs of Brandt’s cormorants and 486 pairs of western gulls in 1995 (with incidental observations of a smaller colony as early as 1991) and grew to a peak of 4,825 cormorant pairs in 2023; gull numbers are holding steady at approximately 1,000 breeding pairs. However, following three years of record-setting growth of the Brandt’s cormorant colony, the population dropped to 1,337 breeding pairs in 2024. In addition, the cormorant breeding effort and success were dampened, as indicated by smaller than average clutch sizes and lower productivity (chicks fledged per pair). 

Unlike many seabirds that exhibit consistent breeding strategies interannually, Brandt’s cormorants are considered a “boom-or-bust” species. This means that they will vary their reproductive effort in reaction to the surrounding marine conditions. This behavior can explain the drastic decline in the cormorant breeding population and success on Alcatraz in 2024. There were multiple factors contributing to this “bust” year for the cormorants. First, the preceding winter was classified as an El Niño, which typically dampens the coastal upwelling, thus making fewer nutrients available in the broader marine ecosystem. Second, northern anchovy, which typically spawn in San Francisco Bay during the early spring and form the majority of the Brandt’s cormorant diet during their nest initiation phase, were absent from the Bay until late spring. Lastly, the season was marked by heavy rains every 1–2 weeks from February through April, during which time the cormorants would typically be establishing territories and laying eggs. During these storms, the cormorants left the island until the storm passed and then needed to re-establish territories when they returned, thus delaying their nesting. These factors came together in 2024 to cause the drop in cormorant population, delayed their breeding, and reduced their reproductive success. However, while the cormorants may be more susceptible to detrimental environmental factors, they are also able to capitalize on years with favorable conditions, meaning the colony will likely see success again given an improved oceanic environment. 

Inspired by the long-term monitoring effort and overall trends of colony growth, researchers at Farallon Institute initiated a pilot study to quantify cormorant colonies using publicly available visual satellite data. The process was documented in the following ESRI Storymap: Alcatraz Seabirds from Space.

Notable observations from the summer CalCOFI at-sea seabird survey

We experienced amazing weather and sea conditions on the summer California Cooperative Oceanic Fisheries Investigations (CalCOFI) cruise, a 16-day ocean survey that took place during the end of July/beginning of August. CalCOFI is a long-term ocean monitoring program and has been collecting at-sea seabird data since 1987. The results of this cruise highlight the importance of these long-term surveys: monitoring over several decades allows us to identify what is a normal pattern and what isn’t, detect changes and trends, and help monitor our ocean’s health. 

However great the weather for this particular survey, the ocean was warm in places and may have been less productive/had less food for marine predators in those areas, but the number of seabirds seen was around normal. Additionally, we saw a number of warm-water seabird species, including a record number of boobies (family Sulidae). These subtropical/tropical species are becoming more common off the California coast. During this cruise, we saw nine individuals consisting of four different species, including red-footed, masked, Nazca, and Cocos/brown boobies. Along with the boobies was another notable warm-water species, a red-billed tropicbird. Red-billed tropicbirds breed around western Mexico and in the Gulf of California and are occasionally seen off California during late summer. Lastly, we also saw record numbers of elegant terns for this time of year. Elegant terns are known to be shifting their range northward from Mexico into California, and our observations confirm this continued trend.

- Guest written by Tammy Russell