BART: Nesting Pigeons Got in the Way of S.F. Escalator Repair Project

We've heard of all sorts of reasons for service or projects at BART getting slowed down or postponed — everything from people trying to walk through the Transbay Tube to trees falling on tracks to hard-to-trace electrical gremlins.

And BART's escalators have had a reputation for breakdowns and long drawn-out repairs for reasons ranging from station patrons doing rude, unspeakably filthy things to a lack of available parts for the aging equipment.

But here's something new: BART says that an escalator upgrade at its 24th/Mission Station has been delayed for more than a month by a family of pigeons — pigeons! — that took up housekeeping right in the middle of the moving stairway's mechanical works.

The pigeon-prompted postponement came to this news organization's attention via a brief exchange on Twitter.

A patron tweeted the agency during the Monday morning commute, asking why the escalator at the northeast corner of the station remained closed a week after it was due to be replaced and back in service.

The agency responded that work was halted for weeks because "a pigeon set up a nest by the escalator and laid two eggs."

BART also said that "by federal law, we can’t disturb an active nest and monitored the nest every day."

It's not clear what law or regulation protects the birds — formally known as rock pigeons, or Columbia livia. They are among the dozens of non-native species not protected from disturbance under the federal Migratory Bird Treaty Act.

"Crews told us they had to stop work because of the nest," BART spokeswoman Alicia Trost said in an email Monday. "We will inquire about which laws prompted this."

The agency added a pigeon family update, with assurances that last week "the two hatchlings and momma pigeon flew away and we’re moving forward again."

Work on the northeast escalator is now scheduled to be complete in about a month, BART says.

As to how and why the pigeons chose to make a train station escalator their home, maybe they just feel like they fit into the general BART milieu. Here's what the Cornell Lab of Ornithology has to say about the birds' nest selection strategy and housekeeping habits:

Males typically choose the nest site, then sit in place and coo to attract a mate. The site is a nook, cranny, or ledge on either cliffs or manmade structures, often beneath eaves or an overhang. Pigeons may nest in stairwells, in rooms of abandoned buildings, or rain gutters.

During nest building, the female sits on the nest and makes a flimsy platform of straw, stems, and sticks from materials brought to her one at a time by the male. Pigeons reuse their nests many times, and they don't carry away the feces of their nestlings the way many birds do. This means that over time the lightweight nest grows into a sturdy, potlike mound, sometimes incorporating unhatched eggs and mummies of dead nestlings.