The changing of the guard

I begin my walk in darkness, part of a daily ritual at this time of the year. Stepping out into the gloom of the forest with the dogs, I am otherwise alone. I know this patch well and the dark, sometimes shifting, shapes and sounds of the forest no longer hold any fear for me. The sound of something large moving through the vegetation will be one of the many deer and the upright figure that haunts the edge of the track will be a now familiar piece of broken trunk. For many the darkness of night is an unsettling experience, no doubt a reflection of our reliance on the visual. Perhaps we hold within us some primitive fear, an echo perhaps, from our ancestors whose wild woods held the threat of large carnivores long since lost from our countryside.

I have always enjoyed the sensation of being out at night, away from the pervading light pollution that spoils so much of our landscape. The darkness reins in our sight but heightens other senses, most notably those of hearing and smell. The damp, soft air of the forest night holds onto the smells of passing fox and muntjac, and carries the harsh calls of territorial tawny owls and the high-pitched notes of nocturnal migrants like redwing. Whether it is the warm, moonlit summer nights out ringing nightjars or, as now, the pre-dawn walks on damp winter mornings, the dark of the forest embraces you, shortening horizons and engaging you more closely through senses that strain to grasp at sounds and smells.

There have been times, however, when some of night’s sounds have unsettled me. The crack of a rifle close-by or, once in a chestnut wood in Sussex, the sound of footsteps following my nocturnal perambulations. It turned out that the source of these footsteps was a pheasant that had been following me as I worked my way around a regular beat (at the time I was monitoring small mammals with live traps baited with grain). The pheasant had learnt that when I caught something I emptied the grain out and replaced it. My laughter upon discovering this was clearly an outlet for the tension of my nervous energy!

Night’s dark shroud can be slow to slip away on these winter mornings, particularly when the moon is spent or the cloud thick. As the deer retreat from the rides and clearfell, to seek shelter in the thickets and forest cover, so other creatures are stirring. Noisy wood pigeons, roused by my approach, explode from their treetop roosts in a crash of flapping wings, while the calls of crows hang in the air. The world is waking, and it is time to turn for home and breakfast.

Thrushes gather and turn to apples

It is only within the last few days that the birds have turned to the piles of apples, half-hidden by snow, that have sat in the garden practically untouched for weeks. The combination of snow, still several inches deep here in my parent’s garden on the Sussex border, and the berry larder now stripped bare, has driven the thrushes to seek out other opportunities, drawing in Fieldfares and Redwings from the frozen farmland fields and empty hedgerows. There must be a couple of dozen birds in and amongst the low bushes and the long dead architecture of summer’s growth. Blackbirds dominate numerically but it is the larger, more robust, Fieldfares that will have the ultimate say in the pecking order. The small, dark Redwings, with their prominent white eye-stripe and soft call are the birds that catch my eye though. I have fond memories of handling dozens of these Nordic visitors whilst ringing at a Norfolk orchard near Ashill and they are a very rare visitor to my Norfolk garden.

The Redwings are true nomads; pushing south in autumn from their northern breeding grounds they can be heard at night, their soft calls a much-stated omen of the approaching winter. The numbers wintering here are variable, reflecting the changing patterns of food availability and the vagaries of the weather. An individual wintering here in one year could just as easily be found wintering in northern Italy the following year. Because of their size and their preference for soil-dwelling invertebrates, Redwings can struggle when the winter weather is at its worst. Hard frosts and snow cover prevent access to favoured foods and, once the berry crop has also been depleted, they can struggle to find food. It is then that their mobility comes into play, the birds moving further south and west in search of food and more favourable conditions. Those that remain here will increase their use of orchards and gardens, with rural gardens more heavily used than suburban ones.

In with the Redwings there is a single Song Thrush, a species which has been seen less often over recent weeks if the reports that I have received are truly part of a wider pattern. Of similar size to the Redwings, the Song Thrush might also have been struggling with the unfavourable weather conditions. Again, individuals could have been forced south by the weather but some may have remained and succumbed to the bitter cold. We will have to wait for spring to find out.

The apples have become the focus of attention because there is little else left accessible. As birds jostle for this sweet resource, it is reassuring to know that this part of the apple crop has found a good home

The vikings are coming

Hedgerows that a few short weeks ago were plump with berries are now empty, stripped by large numbers of wintering thrushes, including many blackbirds, together with song and mistle thrushes. Snow, thick on the fields in the run up to Christmas, added to the demand for energy-rich berries, pushing redwings and fieldfares off the fields to feed upon the now dwindling berry stocks. Many of the redwings will have been here since late autumn, arriving at night, their nocturnal migrations softly broadcast through their characteristic flight calls. In the mild weather of November and early December these birds will have fed on earthworms and other invertebrates, initially in farmland but later within the more sheltered woodlands where the effects of overnight frosts are greatly reduced.

Redwings are extremely vulnerable to prolonged periods of cold weather and, unable to find food, they quickly use up their limited energy reserves. In the coldest of weather they can suffer very high levels of mortality, something that may explain why the birds may push southwest from Britain into Spain and Portugal if the British Isles are hit by a pronounced cold snap. The birds will also turn to gardens, moving in to exploit any berries remaining on a cotoneaster or holly. Here they will face competition from the larger (and hence dominant) blackbirds and mistle thrushes. The redwings may also make use of windfall apples.

The arrival of these birds often triggers a run of phone calls to the offices of the British Trust for Ornithology (BTO), with people unsure of the identity of these small thrushes seeking advice. Slightly smaller than a song thrush, the redwing is an altogether darker looking bird, streaked below and dirty brown above. The key features to look for are the bold white stripe above the eye (the supercilium) and the red ‘staining’ under the wing which just extends down onto the flanks. Be aware that the song thrush has a rusty-buff underwing that might cause confusion.

Redwings are nomadic in their movements, to the extent that a bird wintering in a Norfolk garden in one year, could be wintering in Italy or Greece the next. Our birds come from two distinct breeding populations, one in Iceland and one extending from Finland through into Russia. Those from Iceland tend to winter in Ireland and northwest parts of Scotland, while those from Finland and Russia tend to winter in the southern half of Britain. The two ‘races’ are subtly different from one another, the Icelandic birds tending to be larger and darker. Interestingly, the species has bred in Britain on occasion, typically when populations elsewhere have been at their peak, something that is no longer the case.

On the move

When you think of bird migration you tend to think of summer or winter visitors, such as Swallow, House Martin or Redwing; birds that are only with us for a small part of the year. This means that many of the birds that are on the move during autumn or spring go unnoticed, simply because they happen to belong to species that you would normally see throughout the year. For instance, birds as familiar to us as Song Thrush, Chaffinch and Goldfinch all either have a migratory component to their British breeding population or to a population elsewhere within wider European range.

While most of our breeding Song Thrushes and Chaffinches are rather sedentary in their habits, some winter abroad in France, Spain, Ireland or Portugal. At the same time, Britain also receives Song Thrushes and Chaffinches arriving here to overwinter, or passing through en route further south during the autumn months. A visit to the Norfolk coast soon after dawn may well reveal some of these visitors. On Sunday morning, for example, I saw and heard good numbers of Chaffinches and smaller numbers of Song Thrushes passing overhead at Kelling Quags, together with other autumn migrants – including Brambling, Siskin and Meadow Pipit.

Both Meadow Pipit and Chaffinch are diurnal migrants (migrating during the day), and the birds I saw may well have been continuing journeys initiated in Scandinavia over recent days. Some of these birds, notably the Brambling, will have made a direct crossing of the North Sea but others, like the Chaffinch, will have avoided the crossing altogether by taking a longer route around the North Sea coast, through the Low Countries and then making a short hop across the English Channel. Such a convoluted journey will have required some nifty navigational skills along the way, given the change in compass direction needed at different stages of the journey.

Another interesting aspect of Chaffinch migration (at least for the birds leaving the northernmost part of the breeding range) is the difference in timing between males and females, and adults and young. Females Chaffinches tend to move before males (and migrate further) and the same is true of young birds, when compared with adults. In the case of the Song Thrush, individuals from different parts of the breeding range show variation in their movements; those from the northernmost populations tend to move the furthest south, with some birds even reaching North Africa. What amazes me about all these movements is not simply that such small birds can undertake such large movements but how individuals of the same species can behave so differently depending upon where they were born, what sex they are or whether they are a young bird or not.

A scatter of winter thrushes

It was wonderfully bright and crisp the other morning, as I explored the fields around Harling. Mobile tit flocks were much in evidence within the small patches of woodland, while great spotted woodpeckers could be heard drumming in the distance.  Near to the Dower House at West Harling I came across a mixed flock of birds that was feeding on an area of overwinter stubble. The flock was not overly large but was spread out over a reasonable area and, as I scanned across it with my binoculars, I was able to pick out a number of different species. Brightly coloured yellowhammers stood out against the stubble, foraging alongside less obvious greenfinches and the occasional chaffinch. Starlings shuffled about with a busy action, searching for food, among similarly sized redwings and larger fieldfares.

The fieldfare is one of my favourite birds, with a gait and pose similar to a mistle thrush but marked more distinctively. The bold, grey head and rump contrast with a rich chestnut brown back, dark wings and a black tail. These wary birds often stand with the neck and head held high, the wings drooped at their side and the tail held horizontally. They have a rapid, almost bounding gait and, when disturbed, they will take to the top of the nearest tree. The redwing is much smaller and more subtly marked than its larger relative. Slightly smaller than a song thrush, the redwing is darker in colour and has a distinctive white stripe above the eye (known as the supercilium). The chest has dark streaks, rather than spots, and the underwing is smudged rufous-orange.

Both species are winter visitors, arriving in autumn from breeding grounds that stretch across Fennoscandia and east into Russia. Arable fields containing permanent pasture and stubble are favoured and the birds feed on earthworms, snails and other invertebrates taken from the surface of the soil. In early winter, fruits and berries feature prominently in their diet but stocks are usually exhausted before the year’s end. Redwings, in particular, struggle during cold weather and will make nomadic movements to escape the worst of the cold. In some years, individuals will venture into gardens in search of food. Although more robust, Fieldfares may also visit gardens to feed on windfall apples.

This flock was one of few that I have seen this winter and there seem to be fewer around this year. It will only be a number of weeks until these wonderful birds begin to depart, though some may linger through into May and occasional birds have summered here in previous years. While their departure heralds the arrival of spring, it will be a shame to see them go.

20 pence flight from Norway

There is something special about birdwatching on the east coast during autumn. You get a real sense that vast numbers of birds are on the move, streaming into the country from across the North Sea. This was something that was brought home to me the other day as I walked the lanes around Happisburgh, enjoying the bright, clear weather that carries just enough edge to let you know that summer is truly over. Small groups of blackbirds were passing overhead, together with smaller numbers of redwings and occasional fieldfares. From the hedgerows, more ragged here than elsewhere in the county, came the high-pitched contact calls of diminutive goldcrests, busy searching for insects. Even though goldcrests breed in Britain (there are some 600,000 pairs nationally), these particular individuals were more likely to be migrants, freshly arrived from Scandinavia or western Russia.

As well as being the smallest British bird, the goldcrest has the distinction of being one of the lightest birds anywhere in the world to make regular sea crossings as part of an annual migration. For a bird that weighs roughly the same as a twenty pence piece (about 5.3 grams) such movements are truly remarkable. In some years, bushes and hedgerows at east coast sites may be literally ‘dripping’ with exhausted goldcrests during autumn. These are birds that must operate very close to their physiological limits. Information generated from bird ringing schemes, operating across Europe, has revealed that goldcrests breeding in the northernmost boreal forests are almost completely migratory in their behaviour. Birds from breeding populations situated further south are more likely to remain where they are to overwinter. Some coastal populations on the edge of the Arctic Circle in Norway also remain close to their breeding grounds in winter. By doing so, they have to cope with severe cold and nights that are 18 hours long. It has been calculated that these birds may burn off a fifth of their body weight each night, just to maintain their body temperature at a safe operating level!

This autumn has seen very large numbers of these tiny birds arriving on our shores. Even though the main arrival took place in the second half of October, and was centred on the Yorkshire and Lincolnshire coast, there still appear to be good numbers within East Anglia. Most mornings, while exercising my overly energetic spaniels in Thetford Forest, I encounter goldcrests foraging among the conifers. As if to reinforce the origins of some of these birds, I received a report last week of one individual caught within a mile or so of Thetford which sported a Norwegian ring. One wonders where the individuals I had seen at Happisburgh were from.