Going Wild With Walters -- Archive 2

This is a cumulative archive of the nature column published in the Cambridge Weekly News, from February to December 2003.
For earlier entries see Archive 1, and for more recent entries see Archive 3.

The text is by Martin Walters, and the pieces are usually illustrated by the work of local wildlife artists, notably Michael Wood (mainly birds and other animals) and Stella Tranah (mainly plants).

Maggie from Manchester has sent me a question about birds:

Maggie writes: Why does the dawn chorus start when it's still dark? Could it be that birds prefer the quietest time to sing?

Well Maggie, the general theory is that birds need to sing to attract a mate, and also to hold their territories and keep rivals out, but that during the day they usually have an even greater need to feed themselves. In the early morning, when the light is not so good, it is harder to feed efficiently, so they go into a kind of default sing-mode. In fact birds do sing during the day, but not all at once, and not so much.

Another factor might be that song is more effective when there are fewer other noises to drown them out - their voices carry better at dawn, and may therefore be more effective - except of course that many other birds are singing at the same time! Although many birds sing most around dawn, several also sing at other times, even during the night, most famously of course the nightingale, which is sometimes the only species singing right through the night, albeit intermittently.

There is also a definite sequence of species in the dawn chorus: often robins lead the way, followed by blackbirds and song thrushes, with blue tits and chaffinches joining later on. Some research has suggested that it is the species with the biggest eyes and better vision in the low light of dawn which can afford to sing the earliest. Singing birds are vulnerable to attack by predators, especially in the dusk, and they need to keep visually alert at this time. Nightingales also have large eyes, and presumably acute vision, even at low light levels.

Actually the dawn chorus tends to be at its grandest and loudest after most of the birds have already paired up and established their territories, so there may be another reason. In some species at least, it seems that the dawn singing increases in intensity when the females are most fertile, normally just after egg-laying, which is usually also the time when they are keenest to mate. This is also the time when the male of each pair is most anxious to deter rivals from sneaking in and fertilising their mate, and intense singing is one method of keeping rival males at a safe distance. Females tend to lay their eggs around dawn, after which they are at their most fertile (and receptive) for a couple of hours.

So there is probably a combination of different reasons to explain the wonderful phenomenon of the dawn chorus. Although most of us delight in hearing this free open-air concert, you can be pretty sure that it is not put on for our benefit, nor are the participants 'enjoying' their part in it. Rather they are struggling to ensure their own survival, and that of their offspring, represented by their genetic investment in the next generation.

Singing nightingale by local wildlife artist Michael Wood

We have a friend in Manchester (Maggie) who is splendidly and admirably inquisitive about all sorts of things, and about wildlife in particular. Every so often she sends me a query, which I feel obliged to answer. Even if I don't know the answer myself, I am duty-bound to research it, and thus simultaneously increase my own fund of knowledge. Recently it was spiders that were on her mind.

Maggie from Manchester writes:

"This is Maggie, with a little question about spider welfare: when finding one in the bath, is it kinder to take it down to the cellar, as I have always done, or should they go outside? Does it depend on the time of year? Do they hibernate?"

"Well Maggie this is an interesting question, and one which raises a number of related questions, as do so many biological queries. Your bath spider is probably a Tegenaria (big leg-span; hairy), in which case it would probably die soon if evicted to the outside (especially in Manchester!). These spiders are the ones that make those untidy cobwebs - funnelled, wispy sheets, often in the corner of a window or roof. The best thing would be to place it carefully in a shed, conservatory, cellar, or similar site. I think quite a lot of spiders hibernate, except for some short-lived males which die in the autumn, and some are even consumed by the female after mating, thus recycling vital nourishment for making eggs (food for thought)! This all raises further questions of course about arachnid over-wintering, for which I require notice. These are the big house spiders which lurk in pantries, cellars and the like. Actually there are several similar species, but they are difficult to distinguish. In the late summer and autumn, the males, which have the wider leg-span, wander around looking for a mate, probably following pheromone trails. This is when you might spot one suddenly scampering under the bed, or indeed trapped in the bath. By the way, your spider is likely to have fallen into the bath rather than climbed up the plughole which is what many people assume has happened. The males and females live together for a while (some weeks), before the male dies of old age, at which point he often provides the female with a handy, nourishing snack, useful for when making all those eggs. The females may live for several years. Like most spiders, they lay their eggs in a special egg sac, which they then guard until the tiny spiderlings hatch."

There are about 35,000 species of spider worldwide, of which about 450 occur in Britain and northern Europe. One of our rarest and most attractive species is the wasp spider, Argiope bruennichi (illustrated). The female is large, and coloured brightly in waspish yellow and black. She makes a large web with a zig-zag silk ribbon running across it, but this species is only found in a few places near the south coast. They are more common in France, and I have seen them for example in the Dordogne.

Female wasp spider in her web (illustration by local wildlife artist Michael Wood)

Recently, a neighbour knocked on our door in an excited state. "You won't believe this", she said, "but there's a deer in our garden - what shall I do?" Well, it is now several weeks later and the deer is still there, lurking in her large, shrub-rich garden, sometimes grazing on the open lawn, and making occasional forays into adjacent plots by leaping over the fences. The animal in question is a muntjac, or to be more accurate, Reeves' muntjac, also known as the Chinese muntjac, or barking deer. This tiny deer, only about the size of an average dog, is native to eastern China, and was introduced to Woburn Park, from where some escaped in the 1920s, since when they have gradually built up a large population, mainly in southern England. Though numerous, they are normally hard to see in the wild as they are most active at night, and usually stay in dense woodland or thick undergrowth. They are also rather solitary, and do not form herds like many of the larger deer. Sometimes they betray their presence by their sharp, repeated barking calls. They feed on grasses, bark, leaves, flowers, fruits, and nuts, which makes them less than ideal guests in the average garden.

So how did this muntjac find itself in a suburban Cambridge garden? Well muntjac have increasingly been seen regularly in the city's green spaces - notably on Coldham's Common, and it is but a short jump or canter to Petersfield, perhaps by way of the waste ground alongside the railway lines. Muntjac were first recorded in the county in the early 1960s, and by the 1980s they started to be seen within the city.

Deer have generally increased in Britain over the last century, and they are probably now at their most abundant. Only two are truly native: the dainty roe deer and the large, majestic red deer. The other common deer, fallow, is often seen in managed deer parks or in the grounds of stately homes. Fallow deer were probably first introduced to Britain by the Romans, and many times since via parks; they are now very numerous in the wild. The remaining deer found in this country are: Chinese water deer, reindeer, and sika deer, and all but the last two are found in Cambridgeshire.

Generally, deer are very shy, and hard to spot, except those making up managed herds in parks. Truly wild deer tend to stick to woodland, avoiding open country as much as possible, and usually all one sees are the tracks left in soft mud, or the droppings.

Fallow deer are mostly found in and around the boulder clay woods such as Hayley Wood, and also along the border with Essex, whilst most roe deer sightings are from eastern Cambridgeshire, near the border with Suffolk, notably at Chippenham Fen. Roe deer are very common in the heaths and woods of Breckland. Red deer are less common, being found mainly in the woods south of Newmarket. Chinese water deer, which favour wetland habitats, are sometimes seen at Wicken Fen, but the main breeding site is at Woodwalton Fen.

The first swallows and house martins usually arrive in mid or late April. This year my first swallow was on 20th April, in Grantchester, the first house martin on 27th April, in Cambridge, and the first swift on 28th April, also in Cambridge. The swift was about a week earlier than usual, although last year I also spotted a single swift ahead of the main influx, this time on 26th April. The swifts are pretty constant, with parties normally appearing here during the first week of May.

One of the best places to see and hear newly arrived summer visitors is Wicken Fen. We are fortunate indeed to have this splendid reserve on our doorstep, so why not pay a visit there and experience the fenland in all its glory? This, the first reserve to be acquired by the National Trust, is one of Britain's oldest. It is home to a staggering array of wildlife: 300 species of higher plants, more than 2000 kinds of fly, 1000 different sorts of beetle, 1000 species of moth, and over 200 spiders. One of our rarest plants grows here - the fen violet, and of course Wicken abounds with birds, including specialities such as bittern, bearded reedling, hobby, cuckoo, nightingale, reed and sedge warblers, and even the rather local Cetti's warbler. But probably the star bird of Wicken is the marsh harrier. This superb bird of prey can often be spotted gliding over the reedbeds of Adventurer's Fen, with its wings held in a characteristic shallow 'V'. By now the harriers will be well settled in and starting to breed. They tend to arrive early -- mid to late March -- and occasionally stay over the winter.

In a European context, fenland is one of our most important habitats, as it is not represented well elsewhere, except perhaps in the polderlands and other wetlands of the Netherlands. The reserve has recently been considerably expanded by the purchase of adjacent agricultural land, and there are ambitious plans to increase its size still further, going some way towards recreating the Great Fen which once stretched almost from Cambridge to Lincoln. Certainly extending the acreage of reeds would encourage rare birds such as bitterns to breed regularly. Bitterns are reliable winter visitors to Wicken, but they require a large expanse of reeds for breeding. Perhaps the strange, almost foghorn-like booming call of the bittern will be heard again in the spring at Wicken. Great views of wintering bitterns can sometimes be had from the hides next to the Mere (lake). With their camouflaged plumage and secretive habits they can be hard to spot, until they break cover into shallow water at the edge of the reedbeds.

Though naturally modest, I am compelled to recommend a splendid new Nature Guide, which has details of reserves and other nature sites, including Wicken Fen. Travellers' Nature Guide: Britain by Martin Walters and Bob Gibbons is published this spring by Oxford University Press. It is one in a series of illustrated books offering a practical guide to sites of natural history interest, and other titles cover France, Greece, and Spain. I advise you to snap up a copy, while stocks last!

In the wake of my last article I've had another mobile phone call about waxwings - this time from my artist friend Mike Wood, who was watching a flock of about a dozen in Arbury. Birdwatchers talk about 'waxwing years' when large numbers invade our shores, probably because of the failure of the rowan berry crop closer to home, or after a particularly productive breeding season, or a combination of both these (probably related) factors. In recent years visits by waxwings have become less unusual, and this species could now almost be regarded as a regular, if still unusual and rare winter visitor.

At this time of year I often get contacted by people claiming to have heard a nightingale, and sure enough one came through the other day, nightingales being said to be serenading the inhabitants of Girton. Leaving aside the unlikeliness of the location, I have never heard of a nightingale being seen in Britain in February, let alone singing! Mid-April would be an early date, and singing doesn't usually begin until the bulk of the population has arrived, in late April or early May. The usual suspects are robins, which sing at dawn and dusk, and even through the night, often where there are street lights or some other source of illumination. But as this caller was particularly sure they had heard a nightingale I think that this probably involved a song thrush, many of whose notes have the same quality as part of the nightingale's repertoire.

A famous local naturalist, Norman Moore, who lives in Swavesey, has published an important book, entitled Oaks, Dragonflies and People (Harley Books, Colchester). In this book he explains how he created a nature reserve in his garden, complete with a large pond, or mere, and then catalogued the animals which colonised over the next 40 years -- a remarkable achievement. We often hear the adage: "think global, act local", but I have never seen a more impressive enactment of that recommendation than the efforts Norman Moore describes in his book. You can't get much more local than your own garden pond, nor more global than the themes treated towards the book's conclusion - the future of nature conservation. Anyone interested in garden wildlife and conservation generally should buy a copy.

Travellers to London by train will have noticed another man-made wetland, this time adjacent to the University Press. Each time I make this trip I scan the water, and was pleased last time to see quite a large gathering of black-headed gulls, happily feeding and bathing in Publisher's Pond, as I shall now call it. So, the world's oldest publisher has inadvertently created one of the city's newest wetlands. I shall be watching with interest to see what colonises this oasis, and hope that it persists for some time to come.

Waxwing by local wildlife artist Michael Wood

February 2003

I recently took a rather windy walk in the fenland near to the village of Over. After all the recent rains, Mare Fen, between Over and Swavesey, was a huge sheet of water, and the drainage ditches swirled with the current. Two herons stalked the banks, and groups of mute swans sheltered in the bays, occasionally labouring past in heavy flight, their primaries producing a remarkably loud, musical swishing. 'Chacking' calls gave away parties of fieldfares, and high-pitched 'seeps' their fellow Scandinavian close relatives, redwings. In the fields near the River Ouse the skies were full of circling flocks of lapwings, accompanied, and outnumbered by, hundreds of golden plovers. Back in Over village, I was pleased to see good numbers of house sparrows, merrily chirping and chattering in the hedges. Their much-publicised decline has been patchy, and they are clearly still common in many areas, especially where they have access to good breeding sites and grain.

With the lengthening days, the birds are starting to sing, even though the weather is far from reliably mild yet. Song thrushes, great tits, and blackbirds have been in full song during the earlier mild spell, but the one I always strain to pick out is that delicate, high-pitched song of the goldcrest, one of my favourite birds. Although in my experience they rarely come to feeders, if you have any conifers in your garden, and a keen ear and good eyesight, you might spot one dodging about amongst the twigs, seeking out tiny insects and spiders.

Goldcrests by local wildlife artist Michael Wood