This species is a very localized breeder in SF and since the extirpation of the Lake Merced Colony some 10 years ago the Presidio is the only place where they are known to breed in the last few years.
Last year a couple of nests were built on some of the vacant buildings around Fort Scott but these did not appear to be in use so far this year on a visit last week and this species remains unconfirmed so far this year.
For anyone birding around Crissy Field/Quartermaster Reach keep an eye out for Cliff Swallows coming to the marsh at low tide to gather mud and see if you can track down where they are taking the material too.
