On Tuesday afternoon, Mr. Barrett, 54, returned to the Pond to check on the Mandarin duck. Carrying binoculars, Mr. Barrett, who works as an investor and computer scientist when he’s not birding, circled the shore trying to spot the glamorous creature.

After many minutes of fruitless searching, he spotted the duck nestled near a rock across the Pond, on the eastern shore of the Hallett Nature Sanctuary.

Joined by a fellow birder on a lunch break from her day job, Mr. Barrett began to strategize how he’d coax the duck from the other side, which was thick with trees and shadows in the late afternoon. “We need to be enterprising,” he said.

First, the pair of birders tried to entice him. Mr. Barrett purchased a salted soft pretzel from a cart in the park, ripping off tiny pieces and tossing them off the shore. No luck.

The second birder, Sandra Critelli, muttered that she needed to get back to the office soon. “But that damn duck!” she said.

As his next option, Mr. Barrett tried to chase the duck away from its nook on the distant side of the Pond. After walking around the Pond to the forested nature sanctuary, Mr. Barrett climbed around trees and over branches to reach the shore. Then, he began to quack.

Yes, quack. And soon, a small group of ducks began to swim out of the shadows.

Mr. Barrett sprinted over the bridge and back to the other side of the Pond. By the time he got there, the Mandarin duck was already basking in the sun with his mallard friends, posing for awe-struck onlookers with cameras.