A distant bird often looks like several different birds before becoming indisputably itself. At first it was a gull, but the wings were too deeply arched and there was too much whiteness. Swan then? But it turned slightly and the neck was tucked in rather than sticking out. Little egret then?

But the trailing feet were black, not yellow, the bird was altogether too imposing and now I could pick out the colour of the bill: yellow, not black. It touched down a good half mile away, making a tall and elegant shape, before disappearing behind a small rise in the ground.

Great white egret: now unmistakable: only turned up two or three times in the ten years I’ve lived here. I caught glimpses of the bird throughout the morning; at one point it was standing up on a slight eminence surveying the green Norfolk flood-plain like a tutelary agel.

Then it was in flight again – no it wasn’t, the neck was stuck out like a spout and the action of the wings was far too laboured: this was a mute swan, routinely on the wing round here in winter but still something to marvel at: how do they stay up? They’re the world’s second heaviest flying bird, as I’ve often pointed out before.*

And then, in late afternoon, one more flash of white in the air and there was a barn owl working the marsh before me in the hectic way that barn owls hunt.  Not as big as the previous two white birds but just as compelling. The Broads Authority had come that day to clean out the barn owl box: the perfect place to raise a family.

• The heaviest is the kori bustard of Africa.