Re: Brown Booby swarm
The non-Brown Booby was an immature Blue-footed Booby, which was what I suspected in the field. It came in close to shore for a few minutes before disappearing into the distant Brown Booby swarm. I'm not sure what caused all the boobies to show up — I did an afternoon hike down to the river mouth twice in August and had no Brown Boobies at all. Pictures of the Blue-footed and pictures of some of the larger Brown groups will be up on eBird asap.
Source: SanDiegoRegionBirding Latest Reports