Careful observation revealed the bird was not a Desert Wheatear but a Bull-headed Shrike. Its presence explained why the usually abundant sparrows had vanished from the park.

2016-02-09

When I compared the photographs I had taken, I realized that the bird was not a Desert Wheatear.
I also checked videos of the Desert Wheatear, but it was clearly a different bird.

While following this bird, I noticed something important.
Flycatchers—including the very friendly Daurian Redstart and the Desert Wheatear shown in videos—move their tails up and down.

This bird, however, moved its tail in a circular motion.
At this point, anyone knowledgeable about birds would already have known its name.

It is a very beautiful bird, but I had always thought of it as having a gray appearance similar to a brown-eared bulbul, so I had not recognized it at all.

The bird was a Bull-headed Shrike.

When I searched for “flycatcher-like birds that move their tails in a circular motion,” the answer appeared immediately.
The photographs matched exactly what I had seen.

The Bull-headed Shrike is distributed across Japan, eastern and southern China, the Korean Peninsula, and southeastern Russia.
Its type locality is Japan.

It inhabits open forests, forest edges, riverbanks, and farmland.
It is carnivorous, feeding on insects, small reptiles, amphibians, small birds, and small mammals.

No wonder the sparrows—usually so numerous—were nowhere to be seen.