On a Sunday morning in Singapore’s Ang Mo Kio neighborhood, it’s likely that you’ll hear it before you see it: the gentle coos of hundreds of zebra doves, each one in its own ornate birdcage, 30 feet up in the air. Nearby, there’s the high-pitched chirrups of the white-rumped shamas, red-whiskered bulbuls, and Indian white-eyes—and the idle chit-chat and laughter of the songbirds’ owners. This is the Kebun Baru Birdsinging Club, nestled in the lush greenery of Ang Mo Kio Town Garden West, a suburban park. On a typical weekend,…