Members of the large bluish-gray species with a long serrated beak, absurdly short legs and bright blue webbed feet have been spotted more than 30 times recently. They include six seen relaxing on the breakwater at Marina del Rey.
A similar wave of the birds hit Los Angeles County beaches, lakes and streams in the early 1970s.
"This is the first invasion of boobies since the numbers of birders have swelled," said Kimball Garrett, manager of the ornithology collection at the Natural History Museum of Los Angeles County. "So, there's a lot of happy bird-watchers seeing them for the first time."
Bird experts speculate that the visitors, most of them juveniles, may have been driven north in search of prey fish.
The sightings include one reported to Los Angeles
"He's still really skinny," Kylie Clatterbuck, a rehabilitation technician at the facility, said as the booby preened nearby. "We're going to fatten him up a little bit, then find a nice spot to release him."