The last orchid of summer

Gather a group of naturalists together and the chances are that they will find something interesting to look at and to talk about. Last weekend, a friend’s wedding in Holt brought together a number of naturalists and, in the interval following the meal and speeches, we were able to pop outside and see a colony of Autumn Lady’s-tresses. This delicate little plant, the last of the orchids to flower each year, is a rare species in Norfolk and the opportunity to view it was not one to be missed.

Each plant is small (just 15 cm or so in height) and fragile in appearance. Approaching the lawn, I became aware of a smudge of white sitting just above the green of the lawn itself and creating the illusion of a thin low mist. This effect was caused by the white flowering spikes of Autumn Lady’s-tresses, a vertical spiral of crisp mint-white tubular flowers. To appreciate the flowering spikes fully, you had to get down on your hands and knees – no doubt a comical site to anyone watching us in our wedding finery. These orchids were very much my kind of plant; not garishly bright and shouty but soft and understated. Most had a dozen or so white flowers spiralling up the stem, some spiralled clockwise and others anti-clockwise. There were even a few plants which showed hardly any spiral at all.

Since the flowers open in succession, from the base of the stem upwards, there were some that had finished flowering but with others yet to open. This strategy helps to prevent self-pollination, the plants attracting bumblebees to carry pollen from one plant to another. This approach works well and cross-pollination is pretty much guaranteed. Even so, these orchids can reproduce vegetatively if necessary. Autumn Lady’s-tresses is a plant of southern Britain and is most commonly encountered south-west of a line running from Monmouth to Hastings but there are scattered colonies as far north as Cumbria. Many of the sites on which this orchid once occurred in East Anglia have been lost, invariably areas of damp grassland now drained. Autumn Lady’s-tresses is associated with short nutrient-poor grassland, where it is released from competition from larger and more dominant plants. This old lawn in Holt makes an ideal site, with careful mowing and control over the addition of nutrients keeping potential competitors in check. Proof of the success of the management approach can also be seen in the large number of grassland fungi recorded from the site. Since this species has been lost from more than half of its former range in Britain, it is reassuring to know that this particular site is likely to be secure for many years to come.

Wryneck

In yesterday’s column I touched on the arrival of east coast vagrants, birds that had been drifted to our shores while on their autumn migration south. One of these, the Wryneck, deserves a more detailed piece, not least because of its rather unusual character.

The first thing that strikes you about the Wryneck is its size. As a member of the woodpecker family I’d always expected my first Wryneck to be a substantial creature, similar in size to a Great Spotted Woodpecker. Instead, the small and slender bird that greeted me prompted the involuntary comment ‘it’s tiny!’ In terms of body length the Wryneck is only a little smaller than a Starling but it is of slighter build, a characteristic further emphasised by some of the postures that it adopts. As a child I had a similar response to my first Mole (found dead by the side of the road) and Kingfisher (glimpsed on a local stream); both were significantly smaller than I’d imagined.

With its brown, grey and black vermiculated plumage and its short but pointed bill, the Wryneck doesn’t look like your typical woodpecker either. Unlike other woodpeckers it does not use its tail for support when climbing, nor does it hammer with its bill, preferring instead to chisel away. It can sometimes be seen perching crossways on a branch (again rather unwoodpecker-like) and even its flight bears little resemblance to that of its relatives. Most of the Wrynecks I have seen have been on the ground, either on coastal dunes or the lawns of suburban gardens. In both of these localities the birds will have been foraging, searching the ground for ants.

For me, part of the attraction of the Wryneck is the folklore with which it is associated, even though most of this lore remains firmly rooted elsewhere in Europe. Of particular interest is the name ‘snakebird’, which was used widely across southern England when the bird once bred here in good numbers. This association comes from the defensive display, in which the bird writhes its head around in a strongly reptilian fashion. I have been told that this behaviour is all the more striking when seen at the nest hole, since here the chicks also indulge in the writhing display, occasionally darting out their tongues and all the while uttering a most snake-like hiss. This behaviour, and its effect on nest-robbing children, is wonderfully described in John Clare’s poem ‘The Wryneck’s Nest’.

In the ancient world the Wryneck was ascribed magical powers and associated with various fertility rites. It may have been the bird’s snake-like behaviour that first suggested magical properties, since snakes were strongly associated with fertility. Even now, there is something magical about the Wryneck.

On the move

Early autumn fogs hold the prospect of vagrants from the east. Small migrant birds, setting off from Scandinavia under clear skies, may find themselves drifted west across the North Sea. Here they may encounter a bank of fog or rain, which forces them down on to the East Anglia coast. If the combination and timing of these meteorological conditions happens in a certain way then many hundreds or even thousands of birds may seek the relative security of England’s east coast. This is a truly exciting event for the birdwatcher and an early morning walk among the dunes at Winterton or along the long shingle ridge towards Blakeney Point may yield some stunning birds. The sight of hundreds of Robins or Pied Flycatchers is one not readily forgotten. In with these more familiar migrants may be less commonly encountered species, including various warblers, thrushes and other delights.

Frustration comes when the forecast shows real promise and you have a full day of work ahead, with no prospect of an early morning dash to the coast. The walk out to Blakeney, which is to be recommended, is at least a half-day affair and not something you can squeeze in before work. It is a strange place, an exposed and empty landscape, touched by the hand of past human activities to leave a desolate air. In the clearing mists of early morning, ridges of shingle take on weird shapes and the landscape appears all the more alien. I sometimes feel as if everything else has gone, that human society has disappeared and all that is left are vague echoes of our presence in the form of discards from passing ships and former inhabitants of the point.

The Point at Blakeney has held some nice birds over the last two weeks, with one of my favourites – the Wryneck – reported by visiting birdwatchers. There are some birds that seem ideally suited to a particular place or landscape and the Point is the place that I most strongly associate with the Wryneck. This diminutive member of the woodpecker family was once a regular breeder across much of England but now it is effectively extinct as a breeding species – a real loss.

The arrival of these autumn migrants feels somewhat early this year, no doubt a reflection of the cold autumnal spell felt in the last two weeks of August. I usually associate late September and early October with visits to the coast to watch visible migration in action (the sight of pipits and thrushes passing south at dawn) or to seek out some of our rarer visitors. Even now, the long walk on shingle might be hard work but the rewards are likely to be worth it.

Borderland

I have slipped over the border on the basis of a tip-off, leaving Nelson’s county behind as I cross the river south of Thetford. A friend told me that he had heard them the other night as he drove along the road, windows down because of the sultry conditions. What he had heard was the stridulating song of the Great Green Bush Cricket, one of our most impressive insects. Adult Great Green Bush Crickets are chunky beasts, 4cm long in body and both large and loud enough to be worth a special trip over the border into Suffolk.

This particular colony is well known, close to the road and just across the river from the county boundary. Knowing they are here is one thing because, despite their size, they are not the easiest of creatures to spot. Despite the proximity of the road, there is something gentle and welcoming about this spot; the presence of a heron that lifts slowly out of the shallow water upon my approach and the controlled flight of hawker dragonflies. Beyond the small area of mown grass, no doubt maintained by the Environment Agency to retain access to the small weir, there is a wall of bracken which reaches to head height. It is in here that the crickets will be positioned, away from prying eyes and difficult to reach. I will have to be content with listening to their stridulations, not dissimilar to the more familiar Roesel’s Bush Crickets that stridulate outside work. Even this early in the afternoon there are one or two individuals in song and between the passing cars I can listen and marvel at such a cleverly constructed sound.

These are southern creatures, arriving here after the passing of the last glaciation they have been slow to spread north, highlighting their dependence on warm summers. Most populations are coastal and the species is distinctly local inland. They do not occur much further north than this and so they remain a tantalising colonist, not quite on my patch. Wasteground such as this, dominated with thistles and bracken, meets their needs and this scruffy patch provides ideal habitat.

I venture under the road bridge, working my way along the narrow ledge that sports the old remains of Otter spraints – a sure sign that they are doing well on the river and have ventured upstream from more familiar sites a mile or so distant. The cover on the other side of the road is less suitable, more heavily shaded and I soon head back under the bridge into the warmth of the fading sun to listen to the crickets for one last time. I should return one evening, torch in hand, to see if I can spot them.

Them ruddy ducks!

Conservation can be a brutal business and there are times when sensible, sound and necessary actions require practitioners to implement uncomfortable management options. Nowhere has this been more evident than in the case of the Ruddy Duck. This North American species was first introduced to Britain over half a century ago. Originally held within waterfowl collections, the duck escaped and became established as a breeding species more widely across Britain. By the start of 2000 there were estimated to be some 6,000 Ruddy Ducks living wild in Britain.

The main problem with these ducks was that they did not remain here but instead ranged more widely across Europe and, from the early 1990s, they began to turn up in Spain. Spain is home to the White-headed Duck, a species that is very closely related to the Ruddy Duck and one that has been developing naturally because it is reproductively isolated from its cousin over the water. The newly arrived Ruddy Ducks were found to hybridise with the native White-headed Ducks. If this were allowed to continue then in all likelihood it would lead to the extinction of the White-headed Duck.

Following a great deal of research work, and many discussions, a decision was taken to eradicate the population of Ruddy Ducks living in Britain. Not everyone welcomed this process and there has been a fair amount of bad feeling in some quarters. In some cases the arguments against eradication have been well-intentioned and well-researched; in others they have been ill-informed. The process, however, looks as if it is nearing its end; the latest count suggests that there could be as few as 200 Ruddy Duck left, with many of these associated with traditional sites towards which the eradication work will remain targeted into 2011.

It is a shame that conservation practitioners have been forced to take this action. It is, after all, a consequence of human activities that the Ruddy Duck was brought to Britain in the first place. It is our fault that it escaped and our fault that its presence threatens another species. I know that some readers might argue that if the two ‘species’ can interbreed then they are not really two different species. Such an argument is an oversimplification, since it fails to understand that without our naïve meddling these two species would have remained reproductively isolated because of their geographical separation. Over time they would have become further isolated, as mating behaviours diverged and genetic compatibility declined.

That conservation practitioners must sometimes eradicate a species from an area into which it has been introduced, is never an easy option. It is a sad consequence of the wider damage we humans continue to inflict upon the world.

A silvery tree-top dance

A friend recently told me of a White-letter Hairstreak butterfly that had appeared in her Thetford garden. The butterfly, which spent a few minutes on some climbing beans, soon disappeared but the proximity of the garden to a site where the butterfly had once occurred hinted at its origins. A trip to the site in near perfect weather revealed the presence of at least one other individual and provided welcome news that the colony is still in existence.

The chances are that you may never of heard of the White-letter Hairstreak. It is one of our more enigmatic butterfly species, spending most of its life in and around the canopy of an elm tree. Given the tremendous damage that Dutch Elm Disease did to our hedgerow elms, together with the butterfly’s lifestyle, it is easy to see why this species is so rarely seen. It seems certain that there are many White-letter Hairstreak colonies that go unrecorded and even butterfly enthusiasts tend to just visit the best-known local colonies.

This butterfly derives its name from the white hairline markings set against the pale brown underwings. The upperside of the wings is almost never seen, not least because the butterfly sits with its wings folded. Watching the White-letter Hairstreak is best done with a pair of binoculars and, when in active flight, the silvery form of the butterfly can be seen to tumble and circle its way around the treetops. Rarely moving any distance from the elms with which it associates, your chances of getting a close view are not good. There are some places and times where White-letter Hairstreaks descend from the treetops to nectar on thistles or other flowers but they only seem to do this when honeydew is in short supply. Honeydew is the sugary substance produced by feeding aphids; it collects on the surface of leaves and this means that butterfly does not normally have to leave the tree in order to feed. In fact, the entire lifecycle is acted out at canopy level. Courtship, mating and egg-laying all take place high off the ground, with the resulting caterpillars feeding, growing and then pupating within the elm’s luxuriant growth.

Despite the huge impact that disease had on the elm population, the hairstreak has survived well in many of its former haunts. One reason for this may be that the species of elm preferred by this butterfly (the Wych Elm) was less severely affected by Dutch Elm Disease than other species of elm. An additional factor may well be the changing climate, the warmer conditions allowing this butterfly to expand its range northwards. East Anglia was one of the former strongholds so it is worth checking out your local elms.

The lure of Fennel

The fennel that dominates the small bed outside of our kitchen window is alive with insect life. To be honest this is the main reason why I have not moved it elsewhere, tolerating its scruffy domineering form because of the fascination I derive from a few minutes stood watching the many and varied insects that arrive to feast on its juices. At the moment it is the small yellow and black forms of hoverflies that catch my eye, so great is their number. This sudden influx suggests that these are immigrants, newly arrived from continental Europe and part of a wave of immigration that has also delivered the Silver-Y moths that emerge as soon as darkness falls.

Hoverflies have always struck me as interesting insects and, importantly, a group which it is possible to tackle because of the relatively small number of British species (roughly 270) and the relative ease by which most can be identified. Just as there is diversity in their adult forms, with some excellent bee mimics and others strongly reminiscent of certain solitary wasps, so there is diversity in their pupal forms. Some spend their pupal stage in tree sap, some in decaying vegetation and others in water or even dung! I didn’t say they were pleasant, merely interesting.

Of course, it is not just hoverflies that are attracted to the fennel. There are many other small flies, most belonging to families of flies that I have never been brave enough to tackle, plus various beetles, including many familiar ladybirds and soldier beetles. A walk around the rest of the garden soon reveals that the fennel is the main draw at the moment, with the very dry conditions of earlier in the year having greatly reduced nectaring opportunities elsewhere. Fennel has a deep tap root, allowing it to survive well in such dry conditions and, incidentally, making it rather persistent once established.

The attractiveness of the fennel has an obvious parallel away from the garden. Walk along a quiet Norfolk lane or explore a bit of waste ground and you will encounter other plants from the same family as fennel. These other umbellifers also do well for insects, with soldier beetles in particular a common sight feeding on the tiny flower heads. I would imagine that many of these visiting insects are rather short-tongued and that this is why they visit these smaller flowers.

Although fennel is a familiar culinary herb, sometimes used as an ornamental in borders, it has also become established beyond the garden gate. Its Mediterranean origins explain why the Romans brought it to Britain and also why, outside of gardens, it is largely restricted to southern parts of Britain.