A weighty problem

I treasure the reedbed that nestles into a corner of the nunnery lakes reserve. Home to a wealth of wildlife, I have helped to shape its character by periodically removing the invasive growth of willow scrub that threatens to dry it out and change its character. I have been sensitive to the fluctuations in water level that, over the years, have probably reduced its attractiveness to breeding reed warblers. It is an ecosystem in miniature and I relish the opportunity to envelope myself within it and to peer at the richness of tiny invertebrates that live amongst its stems. I have always felt that it looks at its best in winter, on cold still days of large skies and frosted reed heads. This winter, however, it looks somewhat worse for wear.

Large parts of the reedbed have been flattened, the stems of reeds broken and pushed down into the dark, viscous water. It is as if some giant of the African plains as been through, exorcising imagined demons on the vegetation around it. Has some great drama been played out here – something of Man’s doing? A closer examination provides some useful clues; there have been birds roosting here, their nutrient-rich droppings welded to stalks in such quantities that I cannot guess at the numbers of birds involved. In previous winters I have witnessed the dusk arrival of small numbers (dozens each rather than hundreds) of pied wagtails, reed buntings and starlings, all seeking the protection offered by the reedbed during the long winter nights. I suspect that one of these bird species may be responsible and, able to amuse myself elsewhere on the reserve for the short time that remains before the approaching dusk, I plan to return to discover the culprits.

With the light just beginning to fade, I find myself back near the reedbed. This time I am perched up on an area of breck that provides me with a commanding view across the reeds. Small parties of wagtails and starlings can be seen in the air above the reeds, arriving from all directions and travelling in from feeding opportunities elsewhere. It is the starlings that provide the spectacle, their numbers swelling as the natural light begins to drain from the sky and the glow from the distant town becomes a backdrop. Still the numbers of starlings grow – there are thousands in the air now, wheeling and twisting in unison like some swirl of dark ink in water. Then, at some unseen signal, the first birds drop into the reedbed, followed by the others until the whole flock is swallowed up – it’s great weight subduing the reeds and pushing them down. My mystery is solved.

Early Breeding

Dr Johnson famously noted that “when two Englishmen meet, their first talk is of the weather”, a pattern of behaviour that is as relevant today as when it was written. The social anthropologist Kate Fox believes that this “weatherspeak” is not a genuine discussion about the weather at all but a social facilitator, enabling relative strangers to overcome their social reserve and to actually talk to each other. I was pondering on this the other day whilst watching a pair of collared doves establishing their pair bond prior to mating. Our “weatherspeak” is akin to many of the ritualised behaviours exhibited by animals during periods of social interaction. The more questioning among you may be wondering why two collared doves were indulging in such bonding in the middle of winter; well, it’s all to do with the weather.

As I am sure you will have noticed (and, indeed, commented upon to friends and acquaintances) it has been unseasonably mild of late and this has prompted a degree of premature breeding activity amongst some of our bird species. Over the last few days I have received reports of active nests of song thrush and blackbird (both with young chicks), and of other birds seen carrying nesting material. Such reports are not unique and most years there are at least some early nesting attempts taking place in January or even December. The onset of breeding in our garden birds is under the control of hormones, which are themselves triggered by a range of factors, the most important of which appears to be the change in day-length. The hormones set loose changes within the individual bird, including the development of the reproductive organs. Perhaps uniquely among the “higher animals” the reproductive organs of birds shrivel to almost nothing outside of the breeding season but, come spring, they may enlarge by several hundred times. The controlling influence of change in day-length means that, for most species, it is still too early to be preparing to breed. However, there are some species which always seem to feature in early nesting attempts. Along with the odd blackbird, robin, wood pigeon and thrush, there are the tawny owl, which normally starts laying eggs during February, and the collared dove, which seems to keep going all year round, so long as the weather holds.

Over the coming weeks you may start to hear other birds proclaim ownership of breeding territories. A warm day in February or early March might well prompt a great tit to send forth its “teacher teacher” call or a mistle thrush might sing from the tallest of trees. Certainly, if you come across nests with eggs or young I would love to hear of them.

Weather talk

Dr Johnson famously noted that “when two Englishmen meet, their first talk is of the weather”, a pattern of behaviour that is as relevant today as when it was written. The social anthropologist Kate Fox believes that this “weatherspeak” is not a genuine discussion about the weather at all but a social facilitator, enabling relative strangers to overcome their social reserve and to actually talk to each other. I was pondering on this the other day whilst watching a pair of collared doves establishing their pair bond prior to mating. Our “weatherspeak” is akin to many of the ritualised behaviours exhibited by animals during periods of social interaction. The more questioning among you may be wondering why two collared doves were indulging in such bonding in the middle of winter; well, it’s all to do with the weather.

As I am sure you will have noticed (and, indeed, commented upon to friends and acquaintances) it has been unseasonably mild of late and this has prompted a degree of premature breeding activity amongst some of our bird species. Over the last few days I have received reports of active nests of song thrush and blackbird (both with young chicks), and of other birds seen carrying nesting material. Such reports are not unique and most years there are at least some early nesting attempts taking place in January or even December. The onset of breeding in our garden birds is under the control of hormones, which are themselves triggered by a range of factors, the most important of which appears to be the change in day-length. The hormones set loose changes within the individual bird, including the development of the reproductive organs. Perhaps uniquely among the “higher animals” the reproductive organs of birds shrivel to almost nothing outside of the breeding season but, come spring, they may enlarge by several hundred times. The controlling influence of change in day-length means that, for most species, it is still too early to be preparing to breed. However, there are some species which always seem to feature in early nesting attempts. Along with the odd blackbird, robin, wood pigeon and thrush, there are the tawny owl, which normally starts laying eggs during February, and the collared dove, which seems to keep going all year round, so long as the weather holds.

Over the coming weeks you may start to hear other birds proclaim ownership of breeding territories. A warm day in February or early March might well prompt a great tit to send forth its “teacher teacher” call or a mistle thrush might sing from the tallest of trees. Certainly, if you come across nests with eggs or young I would love to hear of them.

Watch out for wild duck

At this time of the year, the disused gravel workings that punctuate the Norfolk countryside are often home to wild duck. Some of these duck will have travelled only a short distance, from breeding sites here in the UK, but others will have arrived from as far away as Russia and Eastern Europe.

The string of flooded gravel workings that sit alongside the Little Ouse to the south of Thetford support small numbers of wintering duck and I often visit them to see what has dropped in. Wild duck are nervous in the presence of humans and so tend to choose those pits that are less disturbed by fishermen and walkers. Just the other day, for instance, there was a flock of thirty or so tufted duck on the most remote of the pits. The striking males, with their blue-black and white plumage, golden eyes and floppy top-knots are instantly recognisable; although the females, more demure in their appearance, can be confused with a number of other species. ‘Tufties’, as they are known, are the most widespread and numerous of our diving ducks. Our small but increasing breeding population has benefited from the spread of gravel workings, with pairs tending to nest on small islands, safe from most predators. Although not something that I have tested, the tufted duck has a reputation of being unpalatable and this may be one of the reasons why it has shown an increase in its breeding population and long-term stability in its wintering numbers.

The adults dive in search of food, favouring a range of invertebrates, especially snails and zebra mussels. The zebra mussel is a recent introduction, first reported from the London docks in 1824, since which time it has spread to many other waterways. Adult male tufties leave the breeding grounds in late June or early July and move to a small number of our larger reservoirs, most notably Abberton Reservoir in Essex, to undergo moult. This behaviour is a form of ‘moult migration’, something that is more pronounced in certain other species, for example shelduck and Canada goose. The arrival of winter sees the tufties on their wintering grounds. Vast numbers winter in the Baltic and on Lake IJsselmeer in the Netherlands and these flocks dwarf the numbers wintering here in Norfolk.

Another duck that may be encountered on the disused gravel workings during winter is the goosander. A member of the sawbill family, so named for the tiny backward facing teeth that line the bill, the goosander feeds on fish – much to the annoyance of sporting fishermen. This long-necked bird has a flat-backed body and sits low in the water, its body shape ideal for underwater pursuit of its prey.

A wet walk

I have been marking time. Brooding over the weather, the wind and rain confining me to the house, I have been studying maps and planning which parts of the county to explore in the warmer, more welcoming, days of spring and summer. Deciding that this won’t do, that the weather will not restrain my wanderings, I dig out a thick woollen hat and my waterproof and head out. With so much water in the air and seemingly oozing from the sodden ground I am drawn towards the river. The waters are brown with silt washed from the fields; in places they push their way up towards the lip of the bank, as if straining to reclaim the vast puddles that cover the bankside path. The thin, elongated, fallen leaves of a willow carpet the ground. Sodden with the rain, their grey undersides resemble small, lifeless fish, disgorged by the angry waters.

Temporarily the path leads me away from the river, skirting a field and a small piece of alder carr, and here I encounter a muntjac. This one is a female, squat in shape and hunched against the elements it is uncertain at my approach, moving off slightly before turning to stare at me intently. Its thick coat must provide a good degree of protection from the rain. Finally, a decision is made and the small deer turns and is soon lost from view amongst the dripping vegetation. There is a real sense of decay in this wood; the fallen leaves and timber, last year’s growth that has died back, all brown and sodden. Only the leaves of the bramble stand out, green and vibrant and screaming of life.

By now the rain has eased somewhat, enough to bring out smaller birds intent on feeding before the light fades. Amid the many blackbirds is a song thrush, its warm tones welcome and lifting my spirits further. Then, as if seeing the song thrush was a good omen, I catch sight of a finch in flight. Heavy and rounded in shape, I follow its course, bringing my binoculars up to catch it land in one of the tall alders that flank the fen. It is a hawfinch, the first I have seen on my local patch and I feel unadulterated joy. I’ve seen these birds before, most winters in fact, at well-known local sites but this one is mine, on my patch and unexpected. Is this reward offered to me as an enticement – look at what you may see if you venture out – or is it pure chance that I stumbled across it? Either way, it is a wonderful bird to see at any time of year, no matter what the weather.

Putting pen to paper

Some of our most famous naturalists are also among the greatest of our diarists, carefully noting observations of a changing flora and fauna over several decades. For the rest of us, while we may not be great diarists we are often persistent in our record taking, hoarding away observations on the animals and plants that we see each day. Such private notes are intended for our own pleasure, should we choose to read them back in later years, and at the end of our days they are unlikely to pass into wider circulation. However, the simple observations that we collect do have tremendous potential for wider use, particularly if they are collected in a systematic fashion. For example, the information held in the nature diaries of a whole generation of naturalists is now being used to study the impacts of global climate change as part of phenological studies.

Phenology is the study of regularly recurring biological phenomena, such as the spring arrival of migrant birds or the emergence of insects from hibernation. There is a long history of systematic recording of this kind within Norfolk. Robert Marsham, of Stratton Strawless, began recording the timings of 27 different indicators of spring in the year 1736, a tradition that was continued by subsequent generations of his family up until 1958. Records from elsewhere within Britain go back to 1703 but even these are dwarfed by the records of cherry flowering that have been collected in Kyoto, Japan, since 705 AD.

More widespread phenological recording began in Britain in 1875, through a network of observers coordinated by the Royal Meteorological Society, but this ceased in 1947. Fortunately it overlapped with an ongoing scheme operated by the British Naturalists’ Association and a further project was launched in 1998; known as the UK Phenology Network (www.phenology.org.uk) it now involves some 19,000 observers and is the largest study of its kind in the world. The new scheme has already produced a wealth of information and, by using historical records as well, has been able to show that spring is now happening earlier than it did just a few decades ago. Different groups of plants and animals have been shown to respond in different ways, with insects seemingly reacting to changing spring temperatures more rapidly than the bird species that feed on them; such that hatching dates of great tits no longer coincide with peak numbers of their caterpillar prey species. Such changing patterns may have a tremendous impact on the nature of our countryside and it is only because of the observations collected by naturalists that such patterns have come to light. So, why not make greater use of your own observations by contributing to phenological recording.

Wood mice take over garden shed

Each winter the local wood mice move into my shed, no doubt seeking more comfortable quarters than those on offer elsewhere within the garden. This pattern of behaviour is something that I have come to tolerate, accepting the small amount of damage to items within the shed. This year, however, I have been forced to take action against these squatters due to the increasing levels of damage and, the final straw, the use of my gardening gloves as a latrine! Over the past three nights I have deployed Longworth live traps in order to catch and remove (to a distant part of Thetford Forest) the mice. So far, seven mice have been caught and I expect to capture more over the coming nights. Such numbers highlight the successes the mice have enjoyed through what has proved to be a mild winter and one with abundant food, in the shape of berries and seeds.

Although territorial during the breeding season, wood mice are loosely social during the winter months, with individuals often nesting communally within their subterranean tunnel systems. This is one of the reasons why numbers can build up in outbuildings at this time of the year. Many observers assume that any mice found within our houses and sheds will be house mice but this is usually not the case. Despite their name, wood mice are fairly ubiquitous across the countryside, exploiting the opportunities available within a wide range of different habitats.  Both the wood mouse and its close relative the yellow-necked mouse are larger than a house mouse, with large dark eyes, big ears and a noticeably long tail. Their warm brown coats have a chestnut/yellow hue and, collectively, these features distinguish them from their smaller cousins. The yellow-necked mouse is more restricted in its choice of habitats and has a more southerly distribution, seemingly only just reaching the southern edge of Norfolk. This means that any mouse with big eyes and ears, long tail and brown coat, seen within the county, will almost certainly be a wood mouse. This is fortunate, since the yellow-necked mouse is very similar in appearance. As its name implies, the yellow-necked mouse has a pale yellow neck patch that extends to form a collar, reaching the brown of the upper neck on each side of the throat. In the wood mouse this feature is usually absent or, if present, it fails to reach the brown of the neck. There is one other fact that you should know about these mice: they have very good homing ability and can easily return to your property if trapped and then relocated to a site less than a mile away. Mine have been relocated to a distant part of the forest!