Saturday, 12 December 2009

Berry good year

It has been a good year for many trees and shrubs, with an abundance of fruit and berries testament to a perfect season weather-wise. Many of the county’s hedgerows are replete with berries, delivering a blur of ripe red colour as you drive along the lanes. This natural larder, currently well-stocked, will support various thrushes through much of the winter; that is, unless it is hit by a hard and damaging frost.

Many plants produce berries as an incentive to birds which, having ingested the berry and the seeds contained within its pulpy coat, will act as dispersal agents, delivering the seeds ready-wrapped in fertilizer to a new site. Given that plants are not mobile, but rooted to a particular place, this form of seed dispersal enables them to colonize new areas. The relationship between the plants and the birds appears to be a mutualistic one, the plant getting help to disperse its seeds and the bird getting a meal in the form of the pulpy berry that surrounds the tough-coated seeds. However, it is complicated by the fact that some birds eat the pulp but discard the seed instead of ingesting it. Others eat the seed and discard the pulp.

Watch the berries in your garden and you might notice that some seem to disappear just as soon as they ripen, thanks to the efforts of thrushes or Starlings. Other fruits, however, remain throughout the winter and are the last ones to be taken by birds. These differences may be related to the composition of the berries, something which may change as the season progresses. For example, many berries show a decrease in their water content over time, matched by an increase in the quantity of lipids (a group of organic compounds that are made up of oils and fats, and which make up the structural components of living cells) they contain.

You might also notice that differently coloured berries may be taken at different times, with red berries taken before yellow, which in turn may be taken before white-berried forms. Recent research suggests that berry colour may reflect nutritional quality, with berries that are black or ultraviolet-reflecting containing higher levels of certain antioxidants.

While the preferences of birds for particular berries may be more complex than you might have imagined, there are implications if you are thinking about planting some berry-producing shrubs this winter. The key is to provide a number of different shrubs, which offer fruits of different sizes and which ripen at different times, thereby extending the fruiting season throughout as much of the winter as posisble. More advice on what to plant can be found at

Friday, 11 December 2009

Lists have a value

Many female readers may subscribe to the view that certain men (and I don’t want to generalise here) have a thing about lists. For some men this fascination with listing and cataloguing takes the form of a collection, perhaps of stamps or coins; in others the item being ‘listed’ or ‘collected’ is more ephemeral and one can include train-spotting or twitching within this particular form of listing. Twitching, for those who do not know, is an extreme form of birdwatching where the object is to see as many different birds as possible, keeping a list for a particular area (say Britain) or for a particular period (a year list or a life list).

Needless to say, there is an element of competition that comes from such listing and twitchers will often brag about the size of their list (assuming it is bigger than that of those to whom they are bragging)! While this competitive element can generate light-hearted banter among birdwatching friends, it can sometimes lead to angry scenes as birdwatchers jostle to view a particularly rare bird. Such behaviour gives birdwatching a bad name and is the main reason that I avoid large twitches.

As a birdwatcher with a much wider interest in natural history, I have never really been into keeping lists, at least not in the form of ‘collecting’ birds as if they were stamps or coins. I keep field notes, listing what I have seen when out and about, noting down the numbers of individuals involved and any interesting behaviour that I have been fortunate enough to witness. Such records are then fed into county bird reports, periodic surveys (such as the BTO’s Bird Atlas project – or into the articles and books that I write. Over the last few years, however, I have been transferring many of these records into site lists for BirdTrack – an online project that uses lists to monitor the arrival and departure patterns of migrants and the change in status of species over time (see for more information). To me, such projects greatly improve the value of my birdwatching, helping to underpin conservation efforts and support important scientific research.

I am always amazed by how few of the birdwatchers that I encounter at Norfolk’s nature reserves have notebooks into which they record sightings. I am equally disappointed when I do end up at a twitch by how little attention is given to the other birds that happen to be at the same site as something rare. Surely, these other birds are as important as something from the other side of the world that has turned up here by chance. Just think, if these ‘listers’ kept proper lists they’d get more from their birdwatching.

Thursday, 10 December 2009

Catch up with our grebes

Strange as it may seem, winter is a good time to catch up with the five species of grebe that either breed or winter within the county. When people think of grebes, they often have an image of the Great Crested Grebe, resplendent in its breeding finery and indulged in an elaborate courtship dance, or the Little Grebe – the dabchick of smaller waterbodies. Both species are less showy in their winter plumage and both may leave their breeding waters to winter elsewhere, where they may swim alongside Red-necked, Black-necked and Slavonian Grebes, all winter visitors to Norfolk.

A trip to the coast can provide views of all five species in a single day and, sometimes, at a single site. The Little Grebe makes use of brackish pools and saline lagoons, with Titchwell and the ditches at Cley both favoured sites. Great Crested Grebes may join them at Titchwell but are more often encountered just off the beach, making use of our inshore coastal waters. Here they mingle with much smaller numbers of the other three species, providing birdwatchers with an opportunity to practice their identification skills.

The Great Crested Grebes leave their breeding sites in the autumn, seeking out larger waterbodies and coastal waters on which to moult, a process which leaves them flightless for several weeks. While several dozen individuals may gather at favoured sites, our wintering population is dwarfed by the 30,000 that moult and winter on the Ijsselmeer in The Netherlands.

Both Black-necked and Slavonian Grebes have small breeding populations in northern Britain (roughly 40-50 pairs each), which are part of a much larger breeding range. While some of our breeders may be among the birds wintering around the Norfolk coast, other wintering birds will have arrived from elsewhere. The size of the arrival is influenced by weather conditions across more northerly waters. All of the species that make use of coastal waters prefer shallow, sheltered bays, which is why Holkham, Holme and Titchwell seem to hold birds to a greater degree than other sites around the county. Here they feed on crustaceans and small fish, often feeding alongside Red-throated Divers and Cormorants.

During the hardest of the winter weather, when bitter winds deliver ferocious storms to our shores, the birds may be forced inland, affording birdwatchers easier viewing than is typically the case when watching these birds at sea. The winter plumages of these birds are dull in comparison with their breeding finery and separation of the different species requires an understanding of the physical structure of each species as well as the plumage pattern. It is worth the effort, however, when you can see all five in a single morning.

Wednesday, 9 December 2009

The enthusiasm of naturalists

Nothing beats being out in the countryside with other naturalists, with people who are full of knowledge and able to deliver their enthusiasm for the natural world. There is so much going on in the natural world, so many different species that you always have a great deal to learn from others who have chosen to specialise on different groups to you.

Take botanists, for example; the other day I spent an afternoon at the Royal Horticultural Society garden at Wisley in Surrey. With me were Brett Westwood (a writer and BBC producer) and Paul Evans (a BBC presenter). Brett is an excellent all-round naturalist, but I suspect that plants are his true passion. Both men were positively bouncing around the garden, full of delight and comment at the range of ferns and plants that were now surviving out of doors, released from the glasshouse by a changing climate. Not only did they know the name of each of these objects of desire but they had a myriad of tales to tell about them. It was truly infectious and I kicked myself for never having got into plants; I have always preferred things that crawl, slide, hop or fly!

Brett gets out and about on a regular basis, turning up new records or rarely observed behaviours with a group of wildlife enthusiasts in the Wye Valley, and I have made similar outings around Norfolk from time to time. Bringing a group of naturalists to a site can reveal the presence of previously unrecorded creatures and the naturalists seem to feed off each other, sharing their collective knowledge in a truly practical way. This is an approach that has been put into practice by the Norfolk and Norwich Naturalists’ Society (NNNS) on a regular basis, with field meetings arranged to increase our knowledge of sites across the county.

One thing that is often missing from such gatherings is the presence of a younger generation, the naturalists of tomorrow who will pick up our magnifying glasses and maintain the knowledge needed to underpin future conservation efforts. Both NNNS and Norfolk Wildlife Trust have been working to develop this new generation by holding events at which youngsters can engage with nature. My own interest, although initially developed alone, gained momentum by being taken to such events by my father; he still refers to the fungus study day where we spent hours wandering a heath in the pouring rain. I have never been so cold or so wet as that day, and I suspect that neither has he!

Being a naturalist is all about retaining that childhood enthusiasm, the desire to find, identify and be fascinated by wildlife; perhaps that is why we bounce about so enthusiastically.

Tuesday, 8 December 2009

Dry autumn leaves a legacy

While the wet weather of recent weeks may be sufficient to cloud the memory, clearing it of recollections of dry autumn days, a visible legacy of autumn’s ‘drought’ has been the poor crop of mushrooms and toadstalls. My weekly walks through mixed and broad-leaf woodland, across fields and heath, have turned up little in the way of fungal fruiting bodies. I would imagine that my experience has been repeated in those who take a more detailed interest in fungi than I achieve with my casual eye.

The building blocks of fungi are the fungal hyphae, thread-like tubes that occur in vast numbers in damp leaf-litter; scoop up a handful of this leaf litter from a damp deciduous woodland and you will soon reveal a cobweb-like mat of fungal strands. These absorb nutrients, either from the soil or from the substance in which they are growing (some fungi grow in and digest wood, while others tackle hair, feathers or the hard exoskeletons of insects). For the greater part of the year hyphae are hidden from view, held within the substrate, but come the autumn they may form fruiting bodies, the familiar mushrooms and toadstalls being one such type. The fruiting bodies allow reproduction and the formation of new colonies, as spores are released to drift on the wind.

Fruiting bodies are produced once the mat of fungal hyphae has reached a certain age or size. Development is then triggered by environmental conditions and research has helped to pinpoint what is involved in this process. In addition to nutrient availability, both soil temperature and humidity are important, with dry ground inhibiting production of the complex fruiting bodies. As anyone who has collected or watched a Shaggy Ink Cap will testify, many of the fruiting bodies are very short-lived (perhaps lasting only for a few brief hours or a couple of days). The tough, woody, bracket fungi, however, are much more robust, with some lasting for 20 years or more and adding a new spore-producing layer each autumn.

The process by which the body develops from the thread like hyphae is fascinating, with a quick progression from a knot of hyphae through to the ‘button’ stage (which is effectively a fully-formed but miniature version of the final body). The next stage is one of expansion, the use of hydraulic pressure increasing the size of the body and forcing it up through the soil’s surface. Such is the strength of the hydraulic pressure that fruiting bodies have been recorded lifting paving slabs and other obstructions.

It is easy to overlook the network of hyphae that drives the production of fruiting bodies but the lack of fungi this autumn is a gentle reminder of their function.

Monday, 7 December 2009

The turning of the tide

It is the first really cold day of winter; a bitter wind driving in off the sea. We have come to Holkham Gap to search for Shorelarks, winter visitors from Fennoscandian breeding grounds that return to favoured traditional haunts in varying numbers late each autumn. Parking on Lady Anne’s Drive, earlier enough in the morning to be just a few strides from the beach, we wander out into the Gap and start scanning the exposed saltmarsh and sandy shingles for birds. Almost straight away we catch the movement of a flock of small birds. This is a mixed flock, mostly Goldfinches but with Linnets and Meadow Pipits among their number, wonderful to see but not what we have come for.

Moving to the east and skirting out towards the ridge of sand we soon come across another small party of birds, this time with nine Shorelarks in their midst, all busy feeding on seeds, including those from the Salicornia. Shorelarks are instantly recognisable birds, peachy-brown in colour with yellow and black head markings and delicate black ‘horns’. They have something of the exotic about them, a feel of the Mongolian desert that perfectly balances their preference for the short vegetation and rough ground that Holkham’s coastal shingles provide. As we watch, the larks move forward with an abbreviated mix of runs, shuffles and crouches, pausing to feed and then briefly disappearing from view behind the uneven ground.

Holkham Gap, Salthouse and Cley are Norfolk’s traditional sites for these birds, the mix of vegetation providing the cover and feeding opportunities that they need. There were few Shorelarks around last winter but this year things are looking better. The pattern of fluctuating numbers is not a new phenomenon and it has been suggested that the size of the autumn arrival is determined by the number pushed west during migration. The bulk of the Fennoscandian breeding population winters in northeast and central Europe and few birds cross the North Sea to our shores. Numbers are also influenced by what has been happening to these birds on their breeding grounds, with the increasing population in southern Norway likely to see increasing numbers wintering here in the future. There are probably several dozen birds here this winter, far fewer than the extraordinary flock of 240 present on 28th November 1998.

While these birds are fleeting visitors to our shores, they have a truly extraordinary global distribution. Widespread across northern Europe, Asia and North America, there is an isolated breeding population in Chile and one in Morocco’s Atlas Mountains. Breeding has even been attempted in Scotland. As winter progresses, the larks will be harder to find, becoming shy and retiring, with some birds moving off to the Continent.