Monday, 28 February 2011

Difficult neighbours

Norfolk is well known for its churches, many of which appear oversized when viewed alongside the small communities they once served. These large and ornate buildings are a legacy from the late medieval period, when a vibrant local economy supported their construction. Norfolk is also known for its round tower churches, of which there are 123 surviving examples – a figure well in excess of the 60 or so to be found elsewhere across the country. Collectively, our remaining medieval churches are important, with a greater concentration existing here than anywhere else in Europe.

The importance of our churches extends beyond their architectural value. Medieval churches provide roosting opportunities for bats and, with a lack of alternative roosting options in some parts of the county, they may be particularly important in this regard. Bats have had a long association with churches and at least eight bat species are known to make regular use of them for roosting. The last national attempt to quantify the levels of use (published in 1997) suggested that roosting bats were to be found in 6,400 churches nationally, a figure that some bat workers feel is a significant underestimate, not least because the bats may go unrecorded if they are only present in small numbers. There is also anecdotal evidence that use may be increasing.

Bat workers like Phil Parker, working alongside local volunteers, have been investigating the use of Norfolk churches by bats and have surveyed some fifty or so sites so far. Six bat species have been noted, with Common Pipistrelle recorded at the greatest number of sites and Natterer’s Bat recorded in the greatest numbers. The other species recorded have been Brown Long-eared Bat, Soprano Pipistrelle, Serotine and Daubenton’s Bat. Only one of the churches so far surveyed was ‘bat-less’, while 19 supported small roosts, 18 held maternity colonies and eight had significant roosts.

It is where bats roost in large numbers within a church that problems can develop. Droppings and urine falling onto pews and artefacts make poor neighbours of the bats, leading to calls in some quarters that the bats should be excluded. With a lack of roosting opportunities elsewhere, the exclusion of the bats could have a significant impact on their local population. Bats are, of course, protected and the Church has to work within the law to find a solution to any problem the bats might present. The real value of the work that Phil Parker is doing comes from the understanding, on a church by church basis, of how the bats are using the building and what mitigation measures might be appropriate to reduce the impact of their presence, so church and bats can move forward as good neighbours.

Saturday, 5 February 2011

Gardens shelter snakes and lizards

I know that my garden supports a small number of frogs and toads. While the frogs were quick to lay claim to my new wildlife pond, spawning in the first spring after the pond had been dug, the toads show a more terrestrial existence, most often appearing on the patio on damp nights to frighten the dogs. The fact that our garden is walled on three sides and located in the middle of town, is probably sufficient reason for the lack of any other amphibians or reptiles. It is known that only the common frog readily penetrates the urban landscape, possibly because of its greater dispersive powers or, more likely, because it is assisted by householders moving spawn from one pond to another.

It seems that the range of reptiles and amphibians you can attract into your garden is, to a greater extent, determined by where your garden is located and the nature of the habitats that surround it. There are some gardens, recently built on former heathland sites in Dorset, that have visiting Adders and Smooth Snakes, the latter a rare species these days. Other rural gardens might support a thriving population of Great Crested Newts or Grass Snakes, and I know of gardens in Norfolk that have both. Less common in most Norfolk gardens is the Slow-worm, not a worm but a legless lizard, with a beautifully patterned body (in the case of the adult males).

Recent research has underlined that the features you have within your garden can also have an influence on which amphibian and reptile species you can support. Open compost heaps are used by Grass Snakes, the elevated temperatures within the mound of decomposing vegetable material help the Grass Snake’s eggs to develop, while stacks of logs and piles of rubble provide shelter for this and other species. There is a garden just down the road from here where the owner has placed sheets of corrugated tin at various points around his large, wooded garden, He now has an impressively large population of Grass Snakes and Slow-worms.

If you are an active gardener like me, then you are more likely to stumble across one of these garden-dwelling reptiles or amphibians but in many gardens they will go unnoticed. Having said this, cat owners sometimes find that their pet has delivered some unfortunate frog, Slow-worm or Grass Snake, which would otherwise have gone unnoticed. The impact of cat predation on some of our reptile and amphibian species might be quite significant, at least in terms of the numbers killed each year. There are likely to be other risks (lawn mowers and garden chemicals to name but two) so the garden can be a difficult place for some species.

Friday, 4 February 2011

Fenland rooks greet a rosy dawn

There is no denying that the fenland landscape can be bleak, dominated as it is by vast skies and little else to break the spirit-level flat horizon. Dull winter days bring brooding skies, the colour leaching from the land and only the deep peaty darkness of the rich black soils remains. The wildlife often seems pushed to the margins and the intrusive sounds of farm machinery and overhead aircraft remind you that this is a landscape in servitude to our needs.

At the same time, there are moments when the Fens can deliver great beauty and, sometimes, a sense of remoteness and closeness to nature. The other morning, for instance, I found myself at Ely station, waiting for a connection into Cambridge. It was still early and a broad sweep of horizon was blushed with soft purples and reds, a legacy of the changing weather and a weak winter sunrise. The sky, deeply patterned, was stunningly beautiful, with a real sense of depth. The feeling of great distance, a sense often felt in these flat lands, was further deepened by the stark silhouettes of distant poplars, two fields away. Few of my fellow passengers seemed to notice the breaking dawn, suffuse with colour. Perhaps they were too engrossed in their phones, papers or morning coffee to notice the spectacle of this particular fenland morning.

Above the murmurings of chattering people could be heard the more strident calls of Rooks, a steady but loose stream of birds crossing the sky and most likely freshly emerged from a communal overnight roost. The calls of these birds, less harsh in tone than those of the equally familiar Carrion Crow, are one of my most favourite farmland sounds. To me, these early nesters herald the approaching spring and it is a delight to see them present in such good numbers. They hint at the first stirrings of spring, of what is to come with the passing of a few more weeks and with the strengthening sun.

The colour of the sky soon changes and the beauty slips away as the colour slides from purple into grey. Then the moment is gone. My train arrives and I manage to grab a window seat to watch the landscape roll past me: dark soils, narrow ditches and fields that appear as vast lakes, so well are they covered in warming polythene. A small group of Whooper Swans loafing in a field, a flight of wild duck and a thick-coated Roe buck, all slip by. There are days when I love the Fens and others when I struggle to find any attachment, so bleak do they seem. There is, however, always some emotional response to this great landscape.

Thursday, 3 February 2011

Breckland's biodiversity revealed

The recent publication of the first Breckland Biodiversity Audit has highlighted the outstanding contribution that the region makes to UK biodiversity. With its low rainfall, free-draining and nutrient poor soils, and continental climate, Breckland is a dynamic landscape, with a long-history of anthropogenic change and a unique community of plants and animals. There are species here that would normally be found on the coast, or whose nearest neighbours are to be found many hundreds of miles away in the Mediterranean Basin. Although the extent of the region as a geographical entity is lost somewhat in the similarly named political boundaries of today, it can be defined as an area of just under 400 square miles, linked by geology, climate and history. It is the land of W G Clarke and his magnificent written portrait ‘In Breckland Wilds’, shaped by the rabbits that ultimately escaped its many warrens and now dominated by plantation forestry, arable enterprise and by the military’s need to train its troops.

Clarke’s great work captured Breckland at a single moment in time. Reading it now conjures up a heathland landscape long since lost and it is easy to mourn its passing and to seek its return. But the Breckland of Clarke’s time (the name Breckland was coined by Clarke) was, in many ways, the direct result of our activities rather than a truly natural landscape. As such, it should be viewed as part of the story and not simply its beginnings. The Breckland of today is, as the audit reveals, still a tremendously important landscape, supporting at least 12,800 species, of which nearly one fifth are priority species for conservation. Perhaps most importantly, nearly a third of all the species for which UK Biodiversity Action Plans have been developed, occur within Breckland.

The audit not only underlines the importance of the region but also highlights the need to direct conservation efforts towards it if we are to maintain its value and retain some of its species, whose populations are in decline as habitats change through our activities. Some of the species under threat actually need the periodic disturbance of the landscape, since they are the species of ephemeral and disturbed habitats. Without a continual renewal to deliver the microhabitat conditions that they require they will be lost if we do nothing, leaving the landscape to stagnate. Of course there is a balance in all this, a real need to maintain lots of different types of habitat within the wider landscape in order to support these diverse communities and the full extent of biodiversity that we can attain. The audit is to be welcomed because it tells us what we have, what has been lost and what we need to retain the rest.

Wednesday, 2 February 2011

Forest supports Coal Tit numbers

Coal Tits are one of the most regular visitors to owl hanging feeders, though not necessarily the most obvious. These small members of the tit family come pretty low down the pecking order and are readily displaced from the feeder by their larger and more robust cousins. Because of this they have adopted a different way of feeding. Rather than sit on one of the feeder ports and feed, they dash in, grab a seed and then fly away to eat it elsewhere. This behaviour reduces the chances of a run-in with a more dominant species.

Sometimes, rather than remove a seed and eat it straight away, they will hide the seed, caching it as an insurance against harder times ahead. They are not the only birds to do this, with Jays and Nuthatches perhaps equally familiar examples. The success of this approach obviously depends on the bird being able to find the greater proportion of the seeds that it has hidden, memorising local clues as to the seed’s whereabouts. Coal Tits and Jays are scatter hoarders, placing individuals seeds in different locations, while the Nuthatch will often hoard the seeds in one location. One of my former colleagues, had a Nuthatch which stored vast numbers of peanuts in a spare-room bed, which the bird gained access to through a small window that tended to be left open during the day! Of course not all the seeds are retrieved, and this is why you might find sunflowers growing in unexpected parts of the garden, or young Oak saplings rising from ground well away from any mature trees.

With their rather narrow bills, Coal Tits are birds which favour coniferous woodland, the narrow bill helping them to probe for insect among the pine needles or to take seeds from the cones. With Thetford Forest right on our doorstep, it is easy to see why these delightful little birds are doing so well around here. Blue and Great Tits prefer deciduous woodland and so only occur in low densities in the regimented stands of Breckland conifers, reducing the amount of competition that the Coal Tits face. Coal Tit numbers may well reflect the size of the cone crop in these conifer dominated habitats. Certainly, their use of gardens increases in those years when the conifer seed crop has been poor, suggesting that they are forced to find food elsewhere.

Coal Tits also face competition during the breeding season and are quickly usurped from many nest boxes by larger birds. Because of this, you tend to find them using cavities with the smallest entrance holes, often low down in damaged tree trunks. They must be doing well though, judging by the numbers seen locally.

Tuesday, 1 February 2011

Nature's lace

It is at this time of the year that we find the occasional lacewing in the house, tucked away in some corner of a room. Small, slender creatures, with soft bodies and finely veined wings, the lacewings are distinctive and not unwelcome visitors. The thin, elongated body is pale in colour, with darker barring touched with reddish-purple – colouring specific to this time of the year. The narrow head balances two large compound eyes, rounded like brassy pinheads and of similar colour. While long antennae extend out from the head, sensitive and ever searching, two pairs of wings are held tent-like over the body, a characteristic shared by a wider group of related species that includes the alderflies and snakeflies.

It is under the microscope that the nature of these insects is most readily appreciated. Only the thick black hairs, which line each of the many wing veins, seem to contradict the delicate, feminine form that underlines the common name of lacewing. Despite their appearance, these are highly effective predators. In their larval form they sport projecting, calliper-like mouthparts with which they seize aphids and other small invertebrates. This preference for aphids makes the lacewing a popular insect with gardeners.  While some of the larvae are narrow of body, matching the adult form, others are squat and cover their body with debris to form a hard protective case. Some of this debris will include the remains of smaller insects, taken as prey, drained of life and then added to the gruesome sculpture on the larva’s back.

Several dozen different species of lacewing are found in Britain, split into two main types. The most familiar of these are the ‘green’ lacewings, often seen in the garden or around the house, early on a summer’s evening. Less familiar are the ‘brown’ lacewings, generally smaller in size and more sombre in appearance. This simple division, based on colour, falls down in the case of the most common ‘green’ lacewing Chrysopa carnea (it has no common name), which changes colour in the winter, replacing soft green with pale brown and reddish-purple overtones. This is the only one of our ‘green’ lacewings to hibernate as an adult, moving into sheltered outbuildings and houses, and so it is almost certainly the only one you will encounter indoors at this time of the year.

All of our lacewings are nocturnal or crepuscular in their habits, and I often see them at lighted windows or around the moth trap. Easily dismissed, because we so rarely give insects a second glance, it is well worth taking a closer look at one with a hand-lens to take in the gauze-like wings or the brassy pinhead compound eyes.