A member has asked our Wildlife Committee for advice on how he can rid his garden of wood pigeons - five are roosting in trees at the bottom of his garden - because they are stripping leaves from a treasured lilac. "As a consequence, the tree is now in a very bad way and I have doubts whether or not it will recover over the winter", he says. "Is there anything that can be done about this pest?"
Since moving into his home near Sydenham 15 years ago, wood pigeon numbers in his garden have markedly increased, he notes. Which would not be surprising, because this is pretty much a nation-wide phenomenon. When the British Trust for Ornithology's intrepid volunteer national bird-recorders rose at dawn to do their annual survey in 2005, they counted a record number of wood pigeons, putting them (for the very first time) head of the Top Twenty Most Commonly-Seen UK list. The BTO's Big Garden Birdwatch rankings of core bird species this Spring has placed the Wood pigeon a little lower, at Number Three: nevertheless, it was seen in 84 per cent of gardens surveyed.
Some 2.5 million breeding pairs of wood pigeons are now reckoned to be living here year-round. Others are migrants, over-wintering in the UK each year during their journey from Scandinavia to France and Spain, where they breed. For this reason, wood pigeon numbers are always at their peak here in winter.
How can you spot the difference between this variety of pigeon and the feral kind - the type that used to hang around Trafalgar Square in vast numbers before Mayor Ken banished them? Wood pigeons are actually unmistakably different-looking birds - larger and less compact than ferals and with a noticeably smaller head, in relation to their body size. In fact, wood pigeons are the biggest variety of pigeon in Europe. But although these grey, white and mauvish-pink birds appear to have very big, heavy bodies (most noticeable when they're seen trying to perch on flimsy twigs) they aren't as fat as they look. That portly shape is mostly feathers and not the result of over-eating grain (their favoured foodstuff). They also eat flowers, grasses, herbs, berries, the odd invertebrate and occasional nut and (pace the aforementioned gentleman's struggling lilac tree) buds, shoots and leaves.
Wood pigeons have always been unpopular with farmers because of their crop-raiding habits (flocks of hundreds, or even thousands, can descend on a field of young corn). The other major difference between feral and wood pigeons is their roosting habits: ferals, being descended from cliff-roosting rock doves, favour buildings with "rocky outcrop" ledges in our towns and cities, while wood pigeons roost in trees and shrubs. But why are they coming into suburban gardens in such numbers these days - and risking having some gardeners "gunning for them", too?
The answer, birdlife charities and research organisations believe, lies in the massive switchover to oilseed rape that's been taking place throughout our agricultural countryside since the 1970s. It seems to have led to a rapid wood pigeon population explosion. And, since their natural home is wooded countryside and fields - and what is a leafy garden if not a "woodland edge" habitat, a park an artificially-created fields with copses and wooded perimeters - it's no wonder they are moving in. These places supply everything that the wood pigeons, average wood pigeon-about-town could possibly need: in abundance.
Wood pigeons seek large, mature trees and shrubs in which to build (their rather scrappy) nests and lay a couple of eggs. They need to be able to feed their young nestlings(which can be born at any time of year) are fed "crop milk", in a safe place away from predators. This food is produced in their parents' throats and jetted directly down their gullets (so youngsters initially make no direct demands on local horticulture). But once the little "squabs" and "squeakers" have left the nest, they'll be out and about, looking among the well-stocked gardens within coo-ing distance of their roost, for a meal.
What's to do, then, to protect your "crop" of garden plants? The Wildlife and Countryside Act, 1981, and its amendments stipulates that all wild birds, their nests and their eggs are protected by law. However, Defra (Department of the Environment, Food and Rural Affairs makes an exception for pigeons, both feral and wood, because they are classed as "nuisance pests".
So, in theory, you could pay someone to trap and remove the birds (but note that many interventions would require a Defra licence first). But it would probably prove a pointless exercise and a waste of money. Other pigeons would soon be flocking in (and nothing guards a prime roosting site than an already-present, hostile sitting tenant or two). A greener alternative might be to purchase a bird-deterrent. There are many Bird Scarer Products on the market, which can be bought via the internet, ranging from glaring, fake raptors to gadgets that make scary noises. A Google search the other day produced 81,700 entries for such products and the law of averages suggests that one or two might work). Or you could arm yourself with a cheap, plastic bazooka-style toy (the kind you fill from the cold tap if you want to start a water fight or discourage a cat from spraying). Eventually, of course, your targeted tree or shrub will develop leaves too mature for pigeons to consume.
Or - and this might sound like sleeping with the enemy - you could feed your resident wood pigeons something they would like to eat, in preference to lilac or other tender shoots - e.g. a grain-mix feed. This solution was the best-bet suggestion from a leading national wildlife organisation because, they said, they had found it to be the most effective (without encouraging further population growth).
It turns out to be the protocol I myself have (unintentionally) been following in recent years. I have one regular wood pigeon garden visitor who waits each morning on an outhouse roof, his yellow eyes (alternately) fixing upon a large tubular bird-feeder while waiting for scraps of high-energy wild birdfood mix (mail ordered)to shower down from the house sparrows' scrummage. My visitor does a good job of cleaning up the grass beneath the feeder and, aware of the resident cats, never lingers longer than absolutely necessary.
It's true that the lilac tree overhanging my fence looks as sick as a parrot these days - but I think its condition must owe more to age and the wisteria that tries to smother it each summer than to the wood pigeons because I have never seen a single one foraging upon it.
For further advice on birds/ bird problems in your garden, contact the RSPB 01767 693 690 or 01273 75333 (office hours); www.rspb.org.uk