So can this be analysed? Should it be analysed? Should anything abstract ever be analysed? Not for me to say, but unfortunately I’m the sort who is cursed with the impulse to try to analyse pretty much everything. So far I’ve failed with the mallards.
It’s easy to understand the appeal of owls and bats flying at twilight. It’s all about energy and function, overlaid with a touch of the mysterious and macabre because nocturnal creatures naturally operate at a time when we generally don’t. And it’s easy to understand the appeal of a skein of geese in spring and autumn. That’s all about the noise they make, and the fact that a big chevron moving across the sky is dramatic, and the further fact that it’s a seasonal marker. But a pair of ducks? All I’ve come up with so far is the tentative notion that it has something to do with the shift from diurnal to nocturnal energies. It’s about transition in the daily cycle. Probably. (But that doesn't explain why ducks are special but wood pigeons aren't.)
And no, it doesn’t really matter why the sight is so special. It just is.