Feathering their nest
Why do birds nest? Great question – and it’s all tied in to their reptilian ancestry. When they conquered the land some 320 million years ago, the evolutionary secret of reptiles’ scaly success was developing a hard, moisture-retaining coating for their eggs… unlike the watery jelly (think frogspawn) that had kept amphibians stuck in or around water up to that point.
After the ‘invention’ of the egg I guess they never really looked back. It meant the predecessors of modern birds were free to crack on with other important developments like wings and learning to fly. Just imagine the issues if you had to carry around a full clutch of developing youngsters in your belly – you’d be literally earthbound. So by depositing their eggs in a nest, modern birds can stay airborne.
The primary job of that nest is keeping the developing clutch warm, dry and safe through their most vulnerable stages of development. And here’s where you come in. As well as providing nest boxes you can lend a helping hand – and at the same time learn a little more about your nesting neighbours. Try putting out a variety of nest material. Raw wool plucked from barbed wire fences while you’re out walking; hair from your (or your pet’s) hairbrush; cotton wool; bundles of feathers. Just experiment, like the birds do! Last year I caught my local blue tits plucking fibres from a piece of woollen carpet covering my compost heap.
If you have younger members of the family (or if you’re secretly looking for an excuse yourself) make some mud pies and put them out on a tray. Many birds like song thrushes (as well as swallows and house martins, of course) take beakfulls of these muddy briquettes away to form the structure of their nests.