A friend of mine kept a list of "ballpark birds" and other species he observed at sporting venues. I can't help thinking that he would have been impressed with White-throated Swift (Aeronautes saxatilis).
These aren't very good photos, but it seemed worth posting them since White-throated Swifts are so awe-inspiring. And perhaps it will encourage other people to keep an eye out for them if attending a SF Giants game at AT&T Park. Photos were taken there on 29 June 2012. (Has anyone seen them at the Oakland Coliseum or Candlestick Park?)
Note the long wings and relatively long tail. The tail has a shallow notch (see next photo). Unfortunately, their striking black-and-white plumage is not visible in these images.
The genus, Aeronautes, means "sky sailor." It describes how they take advantage of air currents and updrafts, as well as their amazing speed and agility in flight. These birds were foraging within and just above the upper deck of the park. But I read that White-throated Swifts were once observed at an air mass convergence zone at 2,500 meters (or 8,202 feet, or 1.5 miles!).
Here are a few other shots taken from the ferry on the way to the park (below). Both are looking west — one with the Golden Gate Bridge and fog in the background, the other with a silhouette of Alcatraz Island.
P.S. I've also seen some nice dragonflies at AT&T Park — probably the best so far is a Black Saddlebags (Tramea lacerata).