Even at the heart of the cacophony, it passes quickly. In little more than an hour, the parrots arrive at their roosts, call one another, divide up into clans, then slip into the sheltering branches of Canary Island pines, where they fall silent for a long night's sleep.
At dawn, after a short wake-up, they are off. "Parrots are like us," says Kimball Garrett, ornithology collections manager at the Natural History Museum. "They commute." The reason most people only see them by day, and then only for a week or so, is that parrots travel across the city by different routes all year foraging for food. They know what's in fruit where before the keenest-eyed gardeners.