Saturday, 28 July 2007

Stone-curlews doing well at Weeting

As I scan across Weeting Heath with my telescope I make a mental note of each creature that comes into view; ‘rabbit, rabbit, rabbit, lapwing, rabbit, rabbit’ goes the count. There are so many rabbits and then, just occasionally, something else, something more interesting comes into focus. Of course, if it weren’t for the rabbits then the stone curlews wouldn’t do so well here. The rabbits keep the turf cropped short, ideal for the stone curlews and for some of the heath’s other inhabitants. Finally, after scanning over countless rabbits, my gaze settles on the pale, more erect shape of a stone curlew.

It is the stone curlews that I have come to see this evening. It is mid-way through their breeding season and there are tiny chicks sheltering alongside their parents, often tucked under a slightly opened wing. They are wonderful to watch, so small but so full of character. I have always thought stone curlews to be thoughtful birds, considered in their movements and ever alert to danger in this exposed landscape. When accompanied by chicks they redouble their watchfulness but, at the same time, they sometimes slip into the resigned posture that human parents show when their own offspring become boisterous or do something inordinately stupid. Tonight, one particular chick seems intent on irritating its parent by wandering away to peck at seemingly inanimate and inedible objects. The parent remains quietly watchful and then suddenly rises to display at a rabbit that has inadvertently strayed too close. Standing tall on its legs, it opens its wings wide to deliver the most intimidating threat display that it can muster.

The nearby lapwings are also harassing the local rabbits, diving at them with screeching calls if they venture near the lapwing’s well-hidden chicks. Both these birds have reason to be concerned. A group of a dozen or so rooks are sat not far off, their angular hunched forms a potential threat to a young and defenceless chick. There are other threats, and not just to the birds; the alarm squeak of a rabbit brings a swift response, with several dozen pairs of eyes and ears now alert to the buzzard crossing the back of the heath, seemingly not hunting but en route elsewhere. It is a reassuring scene; a piece of Norfolk heath packed with new life (the rabbits have young of their own) and these different creatures going about their business. In many ways it seems quite serene, almost calming, but just below the surface lies the menace of nature red in tooth and claw. It will be several more watchful weeks for the various parents before their offspring set off to make their own way in the world.

Friday, 27 July 2007

Has it been a poor breeding season

The question of how our breeding birds have faired is one that I have been asked often of late. The heavy rain and unseasonably low temperatures may have contributed to a poor breeding season and there do seem to be fewer young birds about than usual. Friends who monitor large numbers of nest boxes in different parts of the country have commented on the large number of blue tit and great tit nests that failed, suggesting that one particular band of heavy rain caught them at just the wrong time (heavy rain can wash caterpillars from the canopy and make it very difficult for adults to find sufficient food for their large broods of hungry chicks). Other species that nested slightly later, such as pied flycatcher, seem to have got away with it. This was a pattern also picked up in the southwest by the BBC’s Springwatch team. However, in other parts of the country tits have been reported doing well, so it may just turn out to be a regional problem.

In Norfolk, some of the open nesting species – like blackbird and song thrush – may also have struggled. Regular readers of the EDP will have seen how nesting bitterns and lapwings were washed out by water levels well above average in our reedbeds and wet meadows. While species like bittern are single-brooded and usually only make one nesting attempt, others may get the chance to try again if their first attempt is lost to the weather. Our local blackbird has had at least two unsuccessful attempts this year but has just successfully reared a third brood through to fledging. Mind you, this is more likely to be the result of cat predation, rather than the weather. The blackbirds and tits adopt very different strategies when it comes to breeding. While the blackbird may make several breeding attempts in a season, each with just a few youngsters, the tits adopt an ‘all your eggs in one basket’ approach by looking to rear a large number of chicks in one nesting attempt. This makes sense for the tits, who need to time their nesting attempt to the time of peak caterpillar abundance.

Of course, it will be some time before researchers can make a full and accurate assessment of the 2006 breeding season. Through annual monitoring programmes, like the Nest Record Scheme and Constant Effort ringing, researchers at the British Trust for Ornithology (BTO) will be able to determine the impacts (if any) of the bad weather. They can then compare this information with that gathered in previous years to assess the potential implications for individual populations of our wild birds. So, we need to wait and see what they say.

Thursday, 26 July 2007

Not showy but still a spectacle

Quite deservedly, orchids have a reputation of being showy plants. However, there are several species of orchid that rather let the side down and it was one these that I encountered just the other weekend. In a damp and heavily shaded corner of a Suffolk wood I was shown 16 brittle-looking flowering stalks. These belonged to a small colony of bird’s nest orchid, a species more commonly encountered in the beech woods of southern England. To be honest, the flowering stems looked liked long dead plants but a closer inspection revealed that they were alive. Pale brown in colour, each of the individual flowers that made up the inflorescence was characteristically shaped. The sepals and petals formed an open hood at the top of the flower, while a double lip extended down below, the whole effect strongly reminiscent of common twayblade (a more common and related orchid species).

The flowering spike represents the culmination of the plant’s hard work, acquiring sufficient nutrient reserves below ground to produce and push up a stem; bearing flowers that would be pollinated by visiting insects. This process may take a decade of work, with the plant deriving these nutrients through a rather unusual association with a fungus. The bird’s nest orchid has virtually no chlorophyll and so is effectively unable to carry out photosynthesis, the process so central to most plants. Instead, the orchid gets its nutrients by devouring its living fungus partner which, in turn, obtains its carbohydrates through a symbiotic association with tree roots. In essence, the orchid has cut into a partnership between the tree and the fungus, exploiting both partners to its own advantage. The importance of the fungus is such that seeds produced by the orchid will only germinate where this particular fungus is present and this may be why these orchids are found in clumps within particular parts of a wood.

The English name of the orchid, and also its Latin, is a reference to the appearance of the root system. Each plant has a rhizome around which a tangle of roots radiate out in an untidy manner. This looks very similar to the untidy stick nests built by pigeons and doves. The preference for moist (though not waterlogged) ground within shaded woodland may be one of the reasons why this orchid has declined so dramatically across its historical range. There are just a handful of sites within East Anglia where this plant may be found and so, given the plant’s appearance, it is probably best to visit a known site rather than try and find one yourself. Despite growing up alongside the southern beechwoods, where this species is more common, it remains a spectacle well worth seeing.

Wednesday, 25 July 2007

A perfect summer evening

The air is warm but not quite still and, here on the fen, a male marsh harrier uses this to his advantage as he hangs momentarily above the edge of the reeds. It is a perfect summer evening, with the calm of dusk already beginning to descend upon the scene. A grasshopper warbler whirrs his reeling song, echoed a hundred times over by the softer extended buzzes of calling bush crickets. A few late dragonflies hawk for smaller prey, moving as if controlled by busy electric motors, driving them forward in a rapid mechanical motion. And there, where the reedbed pushes up against the base of the poplar plantation, the dark grey scythe of a hobby drifts past with lazy ease, pitching upwards into a stall that sees it land in one of the trees. The hobby is perched below the reach of the setting sun, in shadow, but such is the strength and colour of the evening light that it remains beautifully lit; it’s rufous ‘trousers’ and black face mask dress it as a smart toreador. Will I get to witness its ballet de mort, as it toys with the sweeping swifts feeding in ever ascending arcs up into the fenland sky?

Out on the water are coot and grebe, all with young in attendance, while closer by a party of swans feeds and utters soft sounds of reassurance. Large carp break surface in the river, their rotund bodies briefly make me think of porpoise, so glossy smooth do they appear in the changing light, with water clinging to them like some wet mucous skin. Along the bank and out into the flooded shallows wade the hefty forms of cattle, with calves in tow, all chewing their way through mouthfuls of luxuriant riverside vegetation. Perhaps disturbed by these bovine interlopers, a grey heron heaves itself up into the air with laboured wingbeats and moves off to find a more peaceful fishing spot.

Smaller birds can be heard, and fleetingly seen, within the reedbeds that sit below the level of this bund, which guides me out and leads me along the sinuous edge of the river, past the great stands of poplars to the expanse of flooded reeds and open ground within which the two pairs of nesting cranes remain so well hidden. The occasional call reveals the continued presence of the orioles, whose young successfully fledged from their high nests over the last two weeks. This is a special place to be on such an evening, highlighting in so many ways why an English summer can be so magical. I feel at one with the creatures around me and know that I have found my true place in this landscape.

Tuesday, 24 July 2007

Don't be put off by wasps

It is a sad fact of life that wasps are not the most popular of insects! Even people who may profess to the enjoyment and appreciation of wildlife can be remarkably intolerant of these busy, buzzy totems of an English summer. The derogatory term ‘waspish’, meaning easily angered, stems from the perception that wasps are quick to sting and I am certain that it is this fear that sets us so strongly against them. As a consequence of this many people only see wasps in terms of their sting; a yellow and black striped menace to be avoided, swatted or sprayed. Yet, this is such a blinkered view of what is a tremendously interesting group of insects. Social wasps, of which we have eight species, have a complex society, centred on the colony’s nest, with a queen and her workers. Nests are marvels of engineering; fabricated from wood fibres and mixed with saliva to form a durable paper. Watch a wasp as it works with its mandibles to remove wood fibres from your fence and you will see what I mean.

Our most familiar species are the common wasp and the German wasp, similar in appearance but distinguished by differences in the facial pattern and by the markings on the abdomen (though these may be surprisingly variable). If you are fortunate enough to encounter a nest, then the variegated mixtures of shades of cream, brown and white will distinguish the nest of a common wasp from the more uniform grey paper produced by the German wasp. Alongside these two species are other, less commonly encountered species including the tree wasp which, despite its name, often nests at ground level. Then, as with many other insect groups, there are the recent colonisers from Europe, extending their breeding ranges northwards thanks to the effects of global climate change. It is one of these, the median wasp, that has been responsible for the over-reaction of much of our tabloid press. Headlines describing the arrival of French killer wasps that can attack without warning are not only alarmist but fall well wide of the mark and only add fuel to the fire of vespine prejudice. What the authors of these articles ignore (other than the facts), and what the readers miss out on, is an appreciation of the benefits that wasps bring to us. Social wasps feed on many of the insect pests that impact on our flowers and vegetables. They also visit flowers for nectar and play a valuable role in pollination. As with all things, knowledge brings understanding and understanding brings appreciation. So take the time to learn about wasps, understand them and appreciate them in the same way you appreciate other wildlife.

Monday, 23 July 2007

Emperor of our summer

To my mind, there is no British insect more impressive than his imperial majesty the purple emperor. Despite its large size, this magnificent butterfly remains an elusive prize for butterfly enthusiasts. It is on the wing from late June through into August but tends to spend most of the long summer days up in the canopy of mature oak woodland. Following many decades of steady decline the butterfly has disappeared from the handful of Norfolk and Suffolk woods where it had been previously reported. However, there are sites in Suffolk where the species has been reintroduced, thanks to the efforts of dedicated enthusiasts, and visits to these sites are often organised by Butterfly Conservation and local wildlife societies.

The stunning beauty of this butterfly is best appreciated at close quarters and, despite its arboreal tendencies, good views can be obtained when the males descend to the ground to probe for mineral salts, taken from the surface of forest tracks or animal dung. The males only do this occasionally and you stand your best chance by arriving early in the season, when the newly emerged males are in greatest need of the minerals. Early to mid-morning on a still warm day is best but nothing is guaranteed.

It is not only the size of the purple emperor that strikes you (they can attain a wingspan of nearly 10cm) but the marvellous purple sheen that adorns the upperwings of the male. This rich purple sheen appears to move across the wing as you change your angle of view. From certain angles it disappears altogether, leaving just the dark brown, almost black, ground colour and the white panels that, superficially, resemble those of the more common white admiral.

The allure of this butterfly has captured the hearts of many lepidopterists. Having encountered the emperor, some have gone on to devote incredible amounts of time to the study and pursuit of this butterfly. The great I. R. P. Heslop, who summarised years of research in his book ‘Notes and views of the purple emperor’, made a point of applying for teaching posts only at schools close to the southern oakwoods frequented by the species. Heslop had spent time in Africa where he hunted big game, including elephant, yet he wrote in his diary that ‘.. nothing in all my sporting or collecting career has ever given me so much joy as the seeing of my first purple emperor safely in the net..’ Fortunately, for the purple emperor, Heslop wasn’t simply interested in collecting; he also put his energies into discovering the life history of the species and into purchasing land to safeguard its future. Let us hope that more of our woodlands are soon graced by its presence.