Recently I went with a group of local naturalists to visit a sand dune system on the coast not far from here. We had to get there via a tourist facility which described itself as ‘the biggest campsite in Europe’. It is always rather weird tramping through such places in boots and anoraks festooned with binoculars and cameras, particularly as in this case there was an adjacent nudist beach.

Big dune systems such as this have a characteristically arid ‘moonscape’ quality, especially from autumn through to spring when muted greens and yellows wash over ridges of blown sand, flat-line slacks and rolling ‘fixed’ dunes held together by grasses and mosses. Dotted amongst these were clumps of sallow bushes each with a singing willow warbler. Particularly striking in these dunes were the many thousands of rabbit burrows and scrapes. Although I didn’t see more than three or four rabbits all day I can only presume that at night they are grazing practically elbow to elbow. Currently the population is obviously booming but I was told that periodically epidemics of myxomatosis have all but wiped them out, leaving the place littered with bones like an ancient battlefield.

There wasn’t much flowering in this chilly, late spring except the tiny yellow beacons on the carpets of creeping willow and hundreds of pale blue heath dog violets scattered over the grassland like discarded fragments of pottery. In a flat bare dune slack one of our party showed us petalwort, a rare and highly protected liverwort (liverworts are related to mosses). This plant was so small that I could only just see it through a x10 hand lens; it looked for all the world like a miniature cos lettuce. A more striking sight was probably us with our heads pressed to the ground and bums in the air; which was no doubt recorded by the endlessly circling drone from the adjacent airfield. Perhaps we are now on somebody’s database as potential jihaddis.

The most intriguing part of the day for me was something altogether different. We were exploring a patch of tall scrub when I spotted a crow’s nest about fifteen feet up in a flimsy sallow. On the ground underneath it were approximately thirty five bleached white rabbit skulls. There were few other bones – just skulls. Through binoculars we could see more skulls incorporated into the fabric of the nest. Out on these lonely dunes it was a bit spooky, as if  some macabre ritual had been taking place. It was also a puzzle: if these were old prey remains how did the crows get them there as, unlike birds of prey, they cannot grasp with their feet. Also where were the bones from the rest of the carcasses?  Surely they cannot have been feeding only on heads. Having mulled it over for a while my best guess so far is that the skulls were from rabbit skeletons scattered across the dunes after the last myxomatosis outbreak, cleaned and bleached by the weather. I am supposing that this pair of crows had a taste for decorating their nest, as many of the crow family do, and had taken a fancy to rabbit skulls. No doubt it was difficult to secure the skulls into the fabric of the nest so they probably dropped many more than they incorporated — and there they lie underneath the tree.

Whether this is the right explanation or not it does highlight the importance of rabbits to the ecology of this dune system. They graze the grassland short, consequently less competitive plants are not squeezed out by taller vegetation; their digging and scraping provide countless patches of bare ground which are colonised and utilised by a variety of plants and invertebrates, and the rabbits themselves are an important source of food for birds and mammals. Whether you are a crow, stoat, lizard or violet gratitude for rabbits seems to me to be in order.