Natterjack toads go for safety over sustenance for their spawn

Last night, a pair of natterjack toads went out in the rain to leave their mark in the meadow. They would have run at a warty gallop to the small ponds in front of the hide. One is an hour-glass shaped pool complete with clouds of green filamentous algae that might have made an edible refuge for their young. The other is a shallower saucer of a pond with little more than sediment for sustenance. The female chose the latter in which to lay her spawn.

As I lean over to look, my shadow is cast over dozens of infant pond skaters, their little legs splayed out as crosses, spread over the surface. They scatter, sending crescent ripples across the water, leaving in the stillness afterwards an uncluttered view to the spawn below. Floating free, the string of black dots is strung out as the natterjack left it in a walk-as-you-lay fashion, the male clasped on her back, squirting out his seed. Drawn out, back and forth in straight lines, it is as if it has been hooked on an invisible cat's cradle. The transparent jelly is fresh and clear, the beady dark eggs roughly paired up through the middle.

In a couple of days, they will relax into a single strand of eggs. But it is hard to see what the hatched young will eat in this underwater desert. The only obvious features are stipples in the sand – last autumn's winged sycamore seeds lying on the bottom. But this is no sunken treasure, for it would seem they are unpalatable. Most have lost only the sail part of their wing, so that the blob-and-tail seeds look like tadpoles. Two of these "tadpoles" suddenly wriggle their tails, scudding through the debris. These are the real thing, well grown, from spawn laid early last month. To the human eye, they are indistinguishable from the tadpoles of frogs or common toads. To overflying mallards, dropping in for a meal, they are probably indistinguishable from the distasteful sycamore seeds. As long as they sit still, the little natterjacks can grow here in open safety.