FARALLONES ISLANDS (Point Blue Conservation Science)—The biggest story on the Farallones so far this year is the earliest peak laying on record for Cassin’s auklets. This species is fine tuned to its environment, where lay dates are highly correlated with the spring transition to wind-driven upwelling along the California coast. This upwelling transports nutrients from the depths up to the sun dappled surface waters to form vast blooms of phytoplankton, seeding the base of the food chain with a rich green soup.
In response to favorable ocean conditions and an assumed abundance of krill that graze upon this plankton, Cassin’s auklets are arriving in force this year, as evidenced by signs of excavation of their earthen burrows and a chorus of calls after dusk.
Point Blue Conservation Science has been closely monitoring the breeding behavior and performance of known-age (banded as chicks) Cassin’s auklets on the Farallones since 1983 and said lay date for this species can be used as a measure of ocean productivity and health.
Following delayed reproduction and a near complete reproductive failure for Cassin’s auklets in 2019, peak lay occurred on March 14th this year, the earliest in Point Blue Conservation Science’s long-term record. This bodes well for many other locally breeding bird and mammal species that also depend on krill either directly or indirectly, so long as favorable conditions persist throughout the spring and summer.