Why is Holden so concerned about the ducks in Central Park during the winter?

In my opinion, Holden is merely making small talk.... and Holden thought Horwitz might know what happened to the ducks.

He was a much better guy than the other driver I'd had. Anyway, I thought maybe he might know about the ducks. "Hey, Horwitz," I said. "You ever pass by the lagoon in Central Park? Down by Central Park South?"

"The what?"

"The lagoon. That little lake, like, there. Where the ducks are. You know."

"Yeah, what about it?"

"Well, you know the ducks that swim around in it? In the springtime and all? Do you happen to know where they go in the wintertime, by any chance?"