The dark rain clouds are lifting after a night of heavy rain. The paths and leaves shine in the morning sunlight. Standing at the top of the hill by the visitor centre, I watch the swallows swoop low, chasing insects over the green field below. The trees are full of birds and their calls, like it’s spring again. A wren chases a chiffchaff. A male and female blackbird, indignant at the arrival of two mistle thrushes, pursue the incomers, chattering. Blue tits, great tits and long-tailed tits seep, whistle and chirrup as they move through the branches.

I hear the soft whistles of bullfinches, hidden in the dense foliage. A large finch flies out from a tall birch, flashing its white rump and black tail, and lands in another tree. The bright pinky-red-breasted male sits on a branch for a moment, spotlit by the sun, and then is gone.

Out across the brooks, newly arriving Canada and greylag geese are congregating on the marsh and fields. Their numbers are building every day, and they’re now being joined by more and more ducks – teal, gadwall, wigeon – as well as lapwings.

The flighty lapwings go up first, squealing and looping, followed by teals and starlings. The bird of prey that’s disturbed them is a large, dark marsh harrier, flying slowly, low above the grass and water. It flaps its wings every few seconds, then floats, searching for prey. It spins round and drops into the long grass. But then it is up again almost straight away, and flaps on. The marsh harrier may be passing through, or it may stay through the winter. With its overall subdued colours but pale inner primary feathers with dark tips, it looks like a sub-adult male in its second autumn. The bird will acquire its more contrasting three-colour wing pattern by the spring.

The song of a skylark pours down from above. I look up and see it hovering high, its wings flickering. In the distance, the clouds are darkening again and a rainbow emerges and fades.