Saturday, 30 June 2007

Sunbathing in the vegetable patch

Given the weather of recent days, I would expect you to raise an eyebrow if I were to say that there had been a spot of sunbathing going on in our vegetable patch. Well, it’s true! There is a sheltered but sunny spot at the base of our bean poles, next to the outdoor tomatoes and just over from what is left of the broad beans. It is not actually me that has been doing the sunbathing – I wouldn’t inflict that on my neighbours – instead it is our resident male blackbird. In between his bouts of parental responsibility he has taken to making the most of the somewhat infrequent sunny interludes to let the sun go to work on his plumage.

A number of bird species appear to be regular participants in a spot of sunbathing, including robins, pheasants and, of course, blackbirds. Our cock blackbird settles down on the soil, spreading his wings and fluffing up his body plumage. By doing so he is maximising the amount of plumage that is exposed to the sun’s rays. It is thought that this serves two functions: first, it helps the all-important preen oil spread across the feather surface, working to keep the plumage in good condition. Additionally, it is thought that by exposing the plumage to the sun, small parasites like feather mites can be controlled more effectively.

Not all birds adopt this technique. Another part of our garden, beneath one of our thicker shrubs, is sometimes used by the visiting house sparrows for dust bathing. The loose, friable soil is worked through the plumage by a series of motions that closely resemble those used for more conventional bathing in water. The bird thrusts down and forward with its chest, the wings working to flick soil particles up and over the body. It may then lean, first to one and then to the other, and repeat the effort.

There are even some of our visiting birds that chose to shower in the garden. In the case of the dunnock this is accomplished by moving through wet vegetation (from rain or dew), while the woodpigeons seem to like nothing better than sit out in the rain. It is clear from their actions that this is not simply a case of being caught in the open and reluctantly accepting that they are getting wet. Instead, they adopt the ridiculous position of lifting one wing up into the air and holding it there, as if they are allowing the rain to wet the underside of their wing. All of these different ablutions serve a similar purpose – to keep the plumage in good conditions and, by doing so, keep the bird warm and fit for flight.

Friday, 29 June 2007

Soldiers and sailors line the lanes

Throughout the months of late spring and summer, the lanes of Norfolk are dressed with the soft white tones of umbellifers. These erect and architecturally interesting plants are members of the carrot family, with their narrow branching stems topped with groups of small white flowers. A succession of species flower as the months progress, starting with the cow parsley that is at its best during May. From late May through into July it is replaced by the somewhat less showy rough chervil, which in turn is replaced by upright hedge parsley come August. These are interesting and diverse plants, which occupy a range of habitats and include species that are edible (for example, alexanders), while others (such as hemlock) are deadly poisonous; hemlock is perhaps best known as the poison given to Socrates at his execution.

As a non-botanist, my interest in these plants is in the diversity of invertebrate life that they attract. Visit a patch of umbellifers on a fine day and you are almost certainly going to encounter some rather smart beetles, various small hoverflies and possibly even a scorpion fly or two. Some of the beetles most often encountered belong to a family called the Cantharidae, better known as soldier beetles. They are typically a couple of centimetres in length, with narrow parallel-sided bodies and brightly coloured wing cases (known as elytra), and they will be familiar to those who have spent anytime in the countryside during summer. There are 40 species of soldier beetle in Britain; many have red or yellow wing cases but others are dull blue or even black. Some authors refer to the dark coloured species as sailor beetles, reserving the name of soldier beetle for the red or yellow coloured species. While this may reflect an association with the traditional uniforms of the different branches of our armed forces, the distinction is pretty unhelpful in the field, especially when it comes to attempting an identification. This is because the colours shown by individual species of soldier or sailor beetle can be very variable; while one individual may be red, another of the same species may be a dirty brown or almost black.

The adult beetles and their larvae are fluid feeders and, while they may feed from plant material, they are typically carnivorous in their habitats, feeding on dead or injured insects. They will also tackle healthy live prey if it is small enough or slow enough to overcome without the risk of injury. These beetles, therefore, are not simply visiting the umbellifer flowers for nectar or pollen. Instead, they are here to find more substantial rewards, in the shape of other insects for food, or a mate to continue their lineage.

Thursday, 28 June 2007

The countryside in your back garden

There are many people who, for whatever reason, are unable to enjoy the countryside proper. Instead, their interactions with the natural world are restricted to the wildlife that visits them in their homes and gardens. While some may view garden wildlife as uninteresting or commonplace, and gardens themselves as a highly managed and artificial habitat, more and more researchers are discovering the tremendous wildlife value of our lawns, borders and shrubberies. Put simply, gardens support wildlife – lots of wildlife. Now, most of this wildlife is not big or showy, nor necessarily that attractive, but it is there and it has great value. While your garden may not be heaving with dozens of different bird and mammal species it will have a myriad of invertebrates, from ground beetles, solitary wasps, flies and other bugs down to even smaller creatures like nematode worms, soil micro-organisms and bacteria. The thing is, you don’t tend to notice, or appreciate, all of this wildlife.

One of the problems with this wildlife being overlooked and undervalued is that gardens themselves are undervalued. This has led to the government classifying urban gardens as ‘brownfield sites’, alongside old industrial land earmarked for development. Over recent years, this reclassification has led to a process known as garden grabbing – whereby property developers buy up houses with large gardens to demolish and replace them with high density housing. Needless to say, high density housing means low density green space and wildlife is pushed out. You might think that this is a sensible solution to the problem of urban sprawl and the pressure placed on Greenfield sites within the wider countryside but it is not as simple as that. You see, much of our wider countryside – at least much of that portion under intensive arable monocultures – is actually pretty poor for wildlife. For example, the foraging opportunities in gardens for bumblebees are far richer than those on offer within most arable farmland. If you lose the larger gardens with their nectar and pollen sources then you lose the bees. We, as human beings, also lose out – starved of our contact with the natural world. Having green space into which you can retreat, to take a breath of fresh air or to enjoy watching wildlife going about its business, is incredibly important to our well-being. To divorce ourselves from the world around us goes against the core of human nature. We are part of the natural world and we have an innate fascination and longing for the comforting presence of other creatures. Such encounters reinforce our sense of belonging, strengthening our place as part of a wider community of life. We should cherish our gardens and the wildlife they contain.

Wednesday, 27 June 2007

Butterfly depends on ants and sun

The complexities of the natural world are easy to take for granted and we are often unaware of the extent to which different organisms are dependent upon one another. Take the large blue butterfly, for example. This, the grandest of our blues, was highly prized by 19th Century butterfly collectors and I have viewed cabinet drawers full of these illustrious insects, collected from sites scattered across the southern Britain. The large blue became extinct in Britain in 1979, not as a consequence of over-collecting but because of changes in the short chalk grassland habitats where it lived.

Like other species of blue, this butterfly has a surprising relationship with ants. After its final moult, a large blue caterpillar falls to the ground and waits to be discovered by an ant. Upon discovering a caterpillar, the ant, in something of a frenzy, will proceed to milk the caterpillar’s honey gland. This may go on for several hours but eventually the caterpillar arches its body and mimics the shape of an ant larva. This mimicry is convincing and the ant, now assuming that it has found one of its brood separated from the nest, takes the caterpillar below ground. Over the following months the caterpillar develops within the ant nest, feeding on ant grubs, before emerging the following summer as an adult. The success of this deception in dependent upon a number of factors. There needs to be an ant nest within about a metre of the thyme plant on which the butterfly egg was laid and this nest should be of one particular species – a red ant called Myrmica sabuleti; other red ants will adopt the caterpillar but large blues practically never survive in the nests of these species. Research has shown that it is the survival of caterpillars within ant nests that ultimately determines the fate of large blue populations. Only where conditions favour Myrmica sabuleti is the large blue able to survive. The ant itself is adapted to warmer climatic conditions than those normally found within Britain, so it is restricted to the shortest grassland swards that occur on steep south-facing slopes. If the sward height increases by just a few centimetres, then the drop in temperature results in the loss of the ant.

By developing a detailed understanding of the interactions that exist between the butterfly, the ants and the chalk grassland habitat, conservationists have been able to re-establish the species in Britain and, importantly, maintain sites at which the butterfly (and the ants) can flourish. It was one of these sites that I visited last weekend to see the successful results of the work – large blues on the wing again in southern England.

Tuesday, 26 June 2007

All hail the tyrant

The river is clear again now that the surge of rainwater, transporting its load of sediment, has passed through. Standing on the bridge I can see the dark torpedo shapes of two jack pike, parallel-sided predators whose broad, almost smiling, snouts conceal vicious, backwards facing teeth. I enjoy watching the pike from this vantage point. They are often here, just downstream from the bridge, hanging almost motionless on the edge of the weeds and waiting for some unsuspecting fish to pass within range. If the prey ventures close enough, the pike will strike its powerful tail to surge forward and grab its meal. This is a sit and wait predator, for over longer distances the pike is a poor athlete.

The pike is an ancient fish, belonging to a family whose closest ancestors have been around for at least 80 million years. I have often heard it said that monks introduced the pike into British waters, some time after the Romans arrived. While there may be some truth in this claim, in that monks may well have introduced this species into certain waters, it is more likely that this is a truly native fish. One of the earliest pike fossils in Britain, taken from the Cromer Forest Beds at West Runton, has been dated as being about 500,000 years old. This native pedigree is reinforced by the presence of pike bones found in Yorkshire peat and pike remains have also been found at ancient settlements, suggesting that this fish has long been hunted by our ancestors.

Over such lengths of time it is, perhaps, unsurprising that a host of legends and superstitions have grown up around the pike. Often, it has been depicted as vermin – through names like water wolf and pond tyrant. There are tales of huge pike taking swans and even small children, yet these are unsubstantiated and may be part of an educational myth, designed to keep small children away from the many other dangers associated with water. Certainly, many fisherman regard the pike as vermin and it is extremely sad to come across the rotting carcass of a pike that has been discarded by a fisherman on the bank of a lake or river. Pike are opportunist predators, taking mainly small fish like dace, roach, rudd and perch, but they will also take ducklings, other waterbirds and water voles. They are also cannibalistic and the removal of large pike from a lake may actually cause problems for a fishery because it is these large pike that control the numbers of smaller jack pike. With no larger pike to control their numbers, the jack pike may exert extra pressure on the populations of other fish.

Monday, 25 June 2007

The King of the Heath

Olive Cook once described the rabbit as being ‘the king of the heath’, a sentiment that still holds true on East Wretham Heath today. A visit during June, especially if made early in the morning, shows the heath to be alive with rabbits. With every footfall, rabbits of various sizes dash away towards the safety of their burrows. This is the only place in Breckland that, perhaps in a small way, still resembles the warrens of old, so prized by their owners as a source of substantial income.

Although the rabbit remains a central part of the Breckland landscape, shaping its soils and raiding the acres of arable crops that have come to replace it, the old warrens have been lost. Today, their ghostly historical presence hangs on only through the echo of lettered names on Ordnance Survey maps or the ruined remains of the stout lodges that housed the warreners. Like other warrens, Thetford Warren probably came into existence soon after the Norman Conquest, at a time when many of the manorial lords were granted the rights of free-warren. Thetford Warren was listed among the possessions of the Thetford Canons in 1338 and it appears in various documents over the following centuries.

The rabbits were treated like domestic animals, being protected as far as possible from the ravages of predators and given supplementary food during winter. They were also heavily protected from would-be poachers, through a system of extremely brutal punishments handed out to those caught stealing rabbits. In 1813, two young men were convicted at the Norfolk Assizes of taking a rabbit from a warren near Hockwold. While one of the men received two years imprisonment, harsh in itself, the other was transported for seven years.

While rabbits may have been destined for the table, especially initially, from at least 1573 they were also marketed for their fur. During the season, rabbits from the warrens around Thetford would be caught in deep pits, known locally as ‘tipes’, covered with a swinging iron plate, to be taken back to Warren Lodge where they were skinned. Harvesting for fur brought with it the introduction of different colour morphs, including both white and silver-blue forms, the latter being considered more valuable than the traditional wild type fur. In more recent times, many of the furs would have gone to the Lingwoods Hat and Fur Factory at Brandon.

Today the rabbit has a different role. At both Weeting and East Wretham Heaths, the rabbits are used to maintain the grassland sward in a manner that is most beneficial to wildlife, including, most notably, the breeding stone curlews so beloved by conservationists. The king of the heath is still working hard for his subjects.

Saturday, 2 June 2007


Although it is not yet five in the morning, it has been light for over an hour. I would say that the morning is still and quiet, save for the chorus of singing birds, but there in the background is the low thumping beat of yet another illegal rave in the distant forest. I am becoming crepuscular in nature, feeling most at ease during the brief hours of dawn and dusk – that period when a certain calm descends over the natural world, as if the animals and birds themselves are unsure about the transition between day and night.

It is at dawn that many creatures seem more approachable and this is certainly the case this morning. Sitting exposed, towards the top of a dead dock, is a grasshopper warbler, reeling out its fly reel song. With head angled up above the horizontal the tiny bird proclaims its ownership of this patch of fen, slowly, almost mechanically, turning its head from side to side. It is a magical sight; later in the day the song will continue but by this time the warbler will have retreated into denser vegetation to remain hidden from view. From across the fen come the dawn songs of other warblers: reed and sedge, with whitethroat chipping in. These birds, each holding their own small territory, are contributing to a cacophony of sound. To me, this chorus is the archetypal sound of spring, revealing how our fens, woodlands and hedgerows are alive with breeding birds.

Today there is a more exotic song, echoing out from the blocks of poplars that sit alongside the fen. Vaguely tropical in nature, this is the beautiful fluting call of a golden oriole, a scarce but annual breeding visitor. Several individuals have arrived since my last visit and I spend much of the next hour engaged in a game of hide and seek, searching out brief glimpses of the yellow and black males as they sing from high in the canopy. Peering in from the track, between the rows of poplars, I am rewarded by all too brief views of several individuals and then, a little later, three in flight between adjacent woodlots. It is a magical time but even this early I do not have the place to myself. Such is the draw of these exotic visitors that others have risen early to see them. Later in the day, many more birdwatchers will arrive, lining up along the banks to get their brief glimpses of the orioles. While they may go away happy with what they have seen, they will have missed so much – all those other birds that have greeted the dawn but are even now beginning to fall silent.

Friday, 1 June 2007

Norfolk's special bat

Built sometime around 1581, Paston Great Barn is an incredibly important building. Not only is it a scheduled ancient monument but it also supports a breeding colony of one of our rarest bats. This is the barbastelle, a species about which are only now beginning to gain a better understanding of its ecology and social behaviour. The breeding colony at Paston was first discovered in August 1996 and at the time it was the only known such colony in Britain. Since then, other breeding colonies have been found in West Sussex, Hampshire, Wales and Somerset, although all of these are in trees, rather than a building. It is worth noting, however, that the use of buildings is more typical on the Continent. It is likely that more colonies will be discovered over the coming years but, even so, there is no doubt that this remains a precariously rare and thinly distributed species.

The barbastelle is, by British standards, a medium sized bat, with dark brown, oily, fur. Short in the face and with large, almost square, ears, the barbastelle has evolved to feed on small prey items located and captured through a slow and manoeuvrable flight. Although the preferred habitat appears to be mature natural or semi-natural woodland, it is clear from studies of the Paston bats that the species is actually rather flexible in its requirements. Radio-tracking studies of the bats, both here and in Sussex, show that barbastelles will feed beneath the canopy during twilight, moving out into more open areas once it becomes properly dark. The bats at Paston make use of the coastal strip between Mundesley and the gas terminal at Bacton, foraging along the shoreline or over the grassy cliffs. Here they take mainly small moths, though other insects also feature, especially when they become abundant.

Paston Great Barn supports a nursery roost, with females and youngsters present during the summer months. Mature males normally roost separately but they have been caught visiting the barn, suggesting that they seek out receptive females with which to mate. This behaviour is only known because of the efforts of Norfolk Bat Group who have devoted time to studying and protecting the bats at Paston. Juggling the conservation requirements of the bats and the barn is not necessarily straightforward.

Because of the difficulties of working with these small, delicate and nocturnal creatures there is still much to learn. Records of barbastelles from elsewhere in Norfolk (from the North Norfolk coast and Breckland) suggest that there are other breeding colonies to be found within the county. Most likely, these will be in trees, located within areas of unmanaged mature woodland, making it all the more difficult to pin them down.