Nature 2010 December

Four legs bad and two legs good

(with apologies to George Orwell!)

A telephone call about a certain flying mammal and an interesting email I saw about pond weed a few weeks ago got me thinking about our sometimes schizophrenic relationship with the plants and animals that we live amongst.

A roadside verge with a splash of daisies can be a welcome site in late Spring. Meanwhile a golf green awash with bellis perennis, to give the flower its official name, is a greenkeeper’s nightmare. Similarly, New Zealand pygmyweed and Japanese knotweed, despite the suggestion in their moniker, may be part of the natural habitat in their country of origin: but here they are unwanted, invasive weeds found in Pallet’s Pond in Cholesbury or in the scrub woodland adjacent to the Hill Fort. Both are on Defra’s invasive non-native species list and need to be eradicated asap. The botanical maxim that sums up this duplicity neatly goes along the lines of: – ‘A weed is just a plant growing in the wrong place.’

A while back I wrote about the insects that share our houses. Though generally we would prefer to rid our properties of most of them, humanely or otherwise, from time to time we may tolerate the odd one and occasionally even proudly cherish them (I’m thinking particularly of those gregarious ladybirds, huddling in crevices over winter). Can we apply a similar principle to plants and weeds and the larger members of the animal kingdom that become uninvited guests in our homes?

Exhibit 1 – The birds we today know as house martins had for eons been building their nests on seaside cliffs. Some time later, perhaps 5 -10,000 years ago, when our ancestors quarried for building materials, the martins moved inland to exploit these newly created habitats. At the same time, the use of quarried stone and timber in building construction encouraged the more opportunist martins to choose to make their home close to human habitation.

These birds are summer visitors and feed on the wing, entirely off insects and with the increasing domestication of animals, the ample supply of insects on farms would have made the associated buildings a good choice of location. It was much the same story with Barn Owls, which must have also moved in on discovering the surfeit of rodents around farmsteads. Like the Dutch and residents of north Germany, who each year welcome back the storks and even provide wagon wheels on their roofs on which the birds build their precarious nests, house owners in Blighty have traditionally thought themselves blessed to have been chosen by house martins to make their home ‘chez-nous’.

Exhibit 2 – Bats tend not to be one of those animals which readily make it onto people’s Top Ten favourite cuddly creatures list. Most of us only experience bats when they appear flying just above our heads, which for some is disconcerting. Added to this are gothic superstitions which still persist, subconsciously at least. Visiting a zoo recently and standing in the walk- through bat enclosure, I was interested to observe a general change to the public’s perception of bats. With an opportunity to view them up close they come across as more endearing creatures.

There are 17 resident species of bat in the UK. All feed on insects and spiders, consuming up to 3,000 in a single night. Back in September I was told about a long-eared bat (which has a wingspan of 12 inches) that had surreptitiously found a temporary home in a spare room. Too early for it to hibernate, it may have come in on a chilly night to find a warm roost for the night and then could not find its way out. It was carefully relocated into a sheltered position outside, leaving the following night.

Bats pair up and mate in September and October and spend the rest of the month building up their fat reserves. In November, as temperatures fall and the volume of insects on the wing diminishes, bats seek out a suitable over-wintering site to hibernate anywhere dry and cool, and may happen upon an opening under the eaves and into the roof space. Most of the older houses in the area will at some time have provided a home for bats. Apart from a few droppings they cause no damage (unlike the other rodents we have to contend with: rats, mice and our not so dear ol’ friend the glis glis.)

Although some bats do hibernate in groups, many will roost on their own to see the winter out. Hibernation implies they sleep through, which is a bit misleading as it’s more like a shallow torpor than a long sleep and they do stir from time to time on the warmer winter nights and take to flying to look for food or water or even to relocate to a new site. If you discover your roof space is a favourite summertime roost for bats, there is no need to disturb them. If you need to do building work and think you may have bats in residence, there are ways of working round them without having to disturb them greatly. For this reason, bat roosts are protected by law and you are required to take and follow advice on how to proceed. There is a very helpful guide available on the Bat Conservancy Trust website at www.bats.org.uk.

Exhibit 3 – Rats and mice are classed as vermin and would readily overrun our houses or outbuildings and contaminate our food larders if we did not take steps to deter or remove them. To these two in this locality we need to add the so-called edible dormouse. However endearing glis glis may look running along the branches of beech trees or on the infra red closed circuit cameras on Autumnwatch, their destructive nature and the risk of disease they harbour when they invade our homes, outweighs any small level of sentimentality for them.

So from these three exhibits it would seem appropriate to twist around a quote from George Orwell’s ‘Animal Farm’ and adopt the maxim ‘Four legs bad, two legs good.’

Whether the pyracantha in our garden still has any of this year’s bumper crop of scarlet fruits on it by the time this article appears is uncertain. As I write there are blackbirds currently enjoying hawthorn berries but no doubt also eyeing up the ‘Fire Bush’ for the dessert course. Fieldfares and redwings will flock in by December. Two years ago I wrote about the infrequent visitors, waxwings, arriving from Scandinavia and reports from the RSPB indicate that it could be another ‘waxwing winter’ this year. These are unmistakable birds with, as I described last time: sleek beige coats overlain with russet brown and with black, yellow and white highlights. They may also be seen in the large car parks of supermarket stores, known for their fruit-laden bushes.