Waking in the small hours, I find my bedroom bisected by a ribbon of light. The waxing gibbous moon hangs like a beaten silver pendant, backlighting wisps of cloud that cling to the inky sky like cobwebs. As I raise my binoculars to view the moon’s craters, I notice a tiny silhouette flutter across the lunar disc.
Nocturnal migration allows birds to spend the daylight hours fuelling up in preparation for the long distances they must travel. It is believed that birds use the stars to help orient themselves, and it is advantageous for them to fly at night when the air is cooler and the atmosphere less turbulent. The cover of darkness also helps them to avoid attack by avian predators.
While spring migration is characterised by the urgency to secure a nesting site and mate, autumnal movement is more leisurely. Radar tracking has revealed that birds consistently fly faster in spring than in autumn. As I moonwatch, I notice that while most migrants drift over in undulating flight, others streak by with purpose. Perhaps because while Hampshire is a staging post or final destination for many birds, some are pressing on to cross the Channel in search of warmer climes.
Millions of birds are flooding into Britain from western Europe, Scandinavia and Russia. Many of our permanent residents are also on the move – warblers, tits and wrens relocating from the countryside to urban parks and gardens; thrushes and wood pigeons flocking from northern Britain to the milder southern counties. So, the seemingly familiar birds thronging our feeders on crisp autumnal mornings may not be the same individuals that held the territory during the breeding season.
I find it impossible to identify the migrants streaming overhead by sight, but I recognise the flutey flight notes of greenshank and the softly pulsing wingbeats of a skein of dark-bellied Brent geese. These birds are heading for the mudflats, where they will swell Langstone harbour’s overwintering population of waders and wildfowl.
Slipping back into bed, I doze off listening to the ethereal “tseep, tseep” contact calls of a flock of redwings passing over my rooftop.
