The other day my 12 year-old daughter and I braved the heavy rain and ventured out for a walk. We headed south from the village, through a meadow, under the railway bridge and back into what we call the Big Field. We walked around the edge of The Pond - the weedy, reed-fringed pool in the centre of the field. A moorhen sat in the middle, but tail-twitched an exit into the reeds on the other side of the pond as soon as it detected us. We stayed still, hoping it would reappear. Suddenly a sharp, high-pitched piping came from the reeds on our side, followed by a querrulous screech. 'Sounds like a water rail', said my daughter, who's pretty knowledgeable about these things, 'but I'm fairly sure we don't get them round here'.
We followed the piping, but as we got closer to the source of the sound it went quiet. Stalking isn't easy when you're picking your way through thick, tussocky grasses and marshy rafts of reeds and rushes. We got as close as we could to the edge of the more open water - my daughter close enough to fill her wellies with pungent, marshy water - and waited.
As I looked across the thin, green porridge of weed-blanketed water, one of the larger lumps of weed lifted a couple of inches, trembled, then slowly subsided again. I thought I saw a dark shape underneath it - a frog maybe. It happened again. This time I had my binoculars on it - and to my amazement saw the head of a moorhen rising out of the water like a freshwater Neptune, its head crowned with dripping emerald weed. It looked around gingerly, spotted us and slowly sank again beneath the surface, like an sinister diver in a James Bond movie, waiting to make his move.
This happened several times, until the bird obviously felt the coast was clear enough to blow his cover, shake off his weedy disguise, and swim back to the opposite reeds. At the same time another, smaller moorhen appeared on our side of the water, behaving in just the same way. It gradually worked its way over to the other side, camouflaged as a lump of weed. The moorhen had been on an undercover operation to rescue its chick.