Birds of prey in Hong Kong divert from flight paths they usually take when migrating, but why? Veteran birdwatcher has the answers
- As raptors grace Hong Kong on a detour from their normal migration routes, a birdwatcher learns the reason is a mix of survival strategy and strong winds

The morning of March 30, I headed to a hilltop vantage above Nam Shan in southeast Lantau. Around 10am, I scanned the horizon over the Chi Ma Wan Peninsula to the south, and saw what I thought was one of the black kites so familiar to Hong Kong, but with thinner wings and a more buoyant flight.
Through my binoculars, I saw the bird was brown on top, pale beneath and had a whitish stripe above each eye, as it passed just east of me, heading north, followed minutes later by several more, gliding on thermals of rising air over the hillside.
I counted 10 in the party, and by the time I left, in the early afternoon, I had tallied 31.
I had been hoping to see these grey-faced buzzards, as this species follows easterly winds through Hong Kong on the periphery of a flyway travelled by around half a million birds a year, on epic journeys of up to 6,000km (3,700 miles) between breeding grounds in eastern Russia, northeast China, Japan and Korea, and winter haunts in the Philippines and Indonesia.