Birds and food stores don’t mix, so when the management of Tesco Great Yarmouth discovered a squatter, they were not amused. Contamination of food by bird dropping is a hazard. There were two wagtails originally, possibly a pair. The windows were left open and the male departed. The female stayed. Nets and traps were deployed to catch her but to no avail. The intruder, it was feared, would have to be shot.
Wagtails are a protected species in the UK. The fine is £5,000 for unlawfully killing one; Tesco would have to apply for an execution warrant. Then, the Great Yarmouth Mercury newspaper got wind of the story and the bird-pooh hit the fan. The squatter became a celebrity; people visited the store to see her. Customers objected to the bird being harmed, so a stay of execution was declared. The wagtail wouldn’t be shot; ringers from the British Trust for Ornithology would catch and remove it. But they have not been needed; the wagtail has disappeared. It has either left the building or is hiding within it.
I don’t envy the ringers their task should the bird return; pied wagtails are very difficult to catch. Of the thousands of birds I have caught and ringed over the last 30 years, only a handful were wagtails. Most small birds ringed nowadays are caught by mist-nets. A Japanese invention, these resemble a huge spider’s web strung between poles. The mesh is so fine that a flying bird can’t spot the net to avoid being entangled. Wagtails, uniquely among garden birds, can take evasive action; their long tails allow them to brake sharply and avoid colliding with the net. If ringers placed mist nets at strategic locations in the supermarket, the black mesh against the bright background of stocked shelves would be too visible.
The wagtail’s tail is a remarkable adaptation. Helicopter designers have copied it. Wagtails and helicopters can hover effortlessly and change direction quickly, even flying backwards. Cities, with their streets of vertical cliffs, are a Godsend to these aerobatic performers. Waste from fast-food joints, the regurgitated remains of drunken nights on the town and discarded titbits from lunchtime sandwiches, attract the creepy crawlies wagtails like to eat. The pointed, tweezer-like bill can extract little creatures from cracks in walls and pavements. Dublin’s wagtails used to be famous. On winter nights, they would converge on O’Connell Street to roost in the plane trees, now gone, which adorned the central aisle. Sheltered from the elements by tall buildings, the sleepers were safe from predators. The heat-island effect of the city made this the warmest location in Leinster and there was an added bonus; each wagtail had its own hot-water bottle, a Christmas tree light-bulb.
The wagtail’s manoeuvrability has spawned a curious, if minor, problem. Birds flying near parked cars sometimes see their reflections in wing mirrors. Most species can’t fly slowly enough to investigate the fleeting image. Willie, with his extraordinary tail, can do so, only to attack what he thinks is a rival in his territory. An angry male will return to the mirror again and again.
Wagtails may be gregarious on cold winter nights but, during the day, many have their own exclusive feeding territories. The first one I ever ringed was such a bird. It ‘owned’ my back-garden, but I despaired of ever catching it. One day, however, it blundered into my mist-net. Thereafter, I would see it regularly, the leg-ring confirming its identity. Then, during a ringing expedition at a roosting site 15km away, ‘my’ bird was among the 120 wagtails we trapped. It commuted from there each day, to and from my garden. The Tesco bird, which was caught last week by the British Trust for Ornithology, will be taken far away before release. Otherwise, it might return to its feeding territory: the supermarket.