A pair of brown boobies has succeeded in hatching an egg at Channel Islands National Park/Jim Howard via NPS

It was nearly two years ago that staff at Channel Islands National Park off the California coast noticed that brown boobies, a bird species not typically seen there, were trying to nest. Now the staff has confirmed the hatching of a brown booby chick in the park.

This successful nest, spotted August 24 on Sutil Rock off Santa Barbara Island, signifies a northward expansion of the species' known breeding range in the Gulf of California and along the Pacific coast of Mexico. The closest current breeding colony is located on the Coronado Islands off Northern Baja California, Mexico.

Brown boobies, once considered a rare visitor to the Channel Islands, were observed only 16 times in the 30 years between 1984 and 2014. They were first seen roosting in small numbers on Anacapa and Santa Barbara Islands in 2013. There was a dramatic rise in their numbers in 2015 with more than 170 individuals observed at Santa Barbara Island. Since that time, they have been seen consistently on both islands with fewer sightings occurring on Anacapa Island. 

Adult brown booby/Duncan Wright via NPS

“Seabirds rely upon the rich marine resources and the isolation of these offshore islands to provide food and undisturbed nesting grounds safe from predators,” said Channel Islands Superintendent Ethan McKinley. “With this successful brown booby nest, there are now 14 breeding seabirds that rely upon this vital habitat.” 

Back in November 2017, biologists observed four nests and 102 individual birds on Sutil Island off the southwest end of Santa Barbara Island, the smallest island in the park.Brown boobies, generally considered a tropical or subtropical bird, appear to have been extending their range northward since the 1990s when they first migrated to the Coronado Islands of Baja California from the Gulf of California and Pacific coast of Mexico. This expansion of their range coincides with shifts in oceanic conditions with warmer waters and changes in prey availability. 

An impressive seabird species, brown boobies are known for making spectacular plunge dives from heights of up to 50 feet to feed on surface fish. They nest on islands, lay their eggs on the bare ground, and make nests with sticks, rocks, bones, and vegetation to protect them. They winter far out to sea. 

Worldwide, brown booby populations have declined due to habitat degradation on islands where introduced predators have reduced their nesting success.