In winter the local pigeons keep to their own. The bold, feral birds strut and puff on sill and gutter, while the woodpigeons tend to congregate in trees. An ash in Brockwell Park is a favourite with starlings, who click and whistle from its branches as dog walkers, joggers and parents with pushchairs pass beneath. By March it will be pendulous with beckoning black buds, ready to burst into leaves far too fresh and green for its riven, twisted trunk. For now, though, it's dormant, last year's rattling ash keys - and the ribald starlings - its only adornment.