The lid of the first box swung open quite easily. Inside, a haphazard arrangement of fresh moss a few centimetres deep betrayed the recent presence of a nest-building bird. Soon greater structure will emerge from the massed mess of material. First a neat saucer, roughly the dimensions of half a tennis ball. Then the lining: a carefully woven mat of hair, feathers, soft moss or grass that will cradle the eggs and developing young. When they arrive, blue and great tit eggs are miniature marvels: pale cream shaded and speckled with brown spots exactly like a Cadbury’s mini egg.
For birds, this is the season that really counts. Every atom of their being is poured into the effort of breeding. One of the charms of peeking into their lives via the medium of nest boxes is seeing how this story plays out for each individual bird. Not only are the outcomes different for each pair but they seem to have personal style along the way. Favoured nesting sites and even construction materials vary, but the building blocks for one species’ new life are generally the salvaged remnants and leftovers from others’. One box we looked into this week contained a nest of roughly half moss and half badger hair, the only one on site to contain much hair at all so far this spring.
It’s not just the birds, but the very boxes themselves that seem to have peculiarly individual destinies. Their contents are most curiously varied. One box, plastered with mucus on the outside, proved to be brim-full of fat slugs, gelatinously oozing into every available square inch of space. Another few were plugged not by slugs but spiders, their webs with incredible tensile strength that almost rendered the hinged lids unopenable. Insects too find a welcome shelter in nest boxes. Three gleaming ground beetles slunk across the rim of one; elsewhere kidney spot and orange ladybirds hulked down beneath the lids. Earwigs are common guests.
Some invertebrate occupants are less welcome: the odd isolated box hosted an explosion of fleas, carpeting the wood inside and out. They parted at the approach of my hand and leaped towards freedom. At least three stowed away in my trouser pocket to be discovered when I got home. Bumblebees are usually welcome to make use of nest boxes; less helpful was the colony of hornets last summer which so completely subsumed the original construction within their nest that it had to be replaced. Another perhaps more universally palatable non-bird occupier was a wood mouse, its beady eye peering up at me through an impressive depth of snug leaf litter.
Amidst all these signs of new life, death was never far round the corner. Splayed feathers, fragments of bone, a shrunken skull and withered legs were all that remained of an adult great tit that must have been using a nest box as a winter roost. It was a reminder of how ephemeral the life of a small songbird is, and underlines just how vital it is for them to get as many young birds as possible off into the world over the next weeks. The grass is growing, the badgers are shedding, insects are flying, life begins and ends here.