Michael Ellis has this perspective on a sociable and long flying bird.
Right now, passing overhead are thousands of Vaux’s Swifts. They superficially resemble swallows and make a living in the same way - eating flying insects. Swifts are mostly drab and look like cigars with swept back fluttering wings. Swallows have thicker wings and often flash some color. Swifts fly higher and do everything in the air, including copulating. An Old World swift, the Alpine, was found to fly for over six months without landing and even slept in the air! I really have trouble wrapping my head around that unbelievable discovery.
Vaux’s swifts breed locally and north to southeast Alaska, and now are heading south to Central America to overwinter. That’s what happens if you’re an insect eater - in the cold season you've got to move or hibernate.
Traditionally these migrating swifts would spend the night in gregarious groups inside hollowed out huge trees in old growth forests. Well surprise surprise those have been disappearing rapidly in the last hundred years. So, the birds have taken two roosting nightly in abandoned chimneys. But not just any chimney. The chimneys that work for them have to be built before World War II. What? Well after the war the inside of chimneys started to be lined with smooth concrete which makes it difficult for the birds to gain purchase.
The kids at the Chapman Elementary School in Portland, Oregon opted to wear sweaters and hats in the classroom rather than turn on the school’s heater and drive the birds out. Eventually the Audubon Society raised money for an alternative heater. Their now-dedicated chimney supports the largest number of roosting swifts in the world—up to 16,000 nightly. Hundreds of Portlanders gather to watch the evening show throughout September into October.