On the property ladder

From my study window I can see the nest box that I attached to the studio last autumn. It is a robust affair, hand-made and presented to me by a visitor, but it has everything that a cavity-nesting bird could require. Over the winter the box has been used by roosting birds, most likely blue tits, and it is a pair of blue tits that has occupied the box for this spring’s breeding attempt. From my upstairs vantage point I have been able to watch the female – the male does not help with nest construction in this species – taking in moss and grass, a process that has taken many days.

Initially the building was a stop-start affair; the bird would be busy on one warm morning but not the next. Then things became more focussed and the nest building efforts more intense. There is a suggestion, not just from this box but from others elsewhere across the county, that blue tits are running a little late this year. We’d normally expect the first eggs from mid-April but I’d be surprised if this particular pair gets to that stage much before the month’s end.

The timing of a blue tit nesting attempt is important, not least because the birds seek to time things so that the period of peak food demands of their growing chicks matches the peak abundance of the caterpillars on which they feed. The peak in caterpillar abundance follows soon after bud burst, when young leaves are at their most tender and not packed with deterrent chemicals. Of course, bud burst is also running late this year, so the blue tits should not be too far out in their timing. There is a wider concern, however, that a changing climate might eventually lead to a more serious mismatch between the availability of caterpillar prey and the timing of blue tit nesting attempts. This may occur because insects, like moths, are able to respond to a changing climate more rapidly than larger, more complex organisms like birds. We know that, on average, blue tits now nest more than a week earlier than they did a few decades ago, but just how much earlier now is the peak in caterpillar abundance?

My blue tits also face one additional challenge. They are not nesting in a wood – the preferred habitat – but in an urban setting, where fewer caterpillars are available. Urban birds are often less productive and, on average, rear fewer chicks than their country cousins. It may be that many urban pairs are young birds, not able to secure a breeding territory in a better quality habitat, so the option to breed in a garden still provides their best chance of success. 

Evening

It is a beautiful spring evening and without doubt my favourite time of the day. In the hour before dusk, and as the sun slips away, so stillness descends onto the landscape. It is as if things are winding down; the songs of birds dwindle and the brown hares stretch stiffly or scratch at troublesome flies. This early in the year the warmth of the day is insufficient to carry far into evening and there is just enough of a chill in the air to make me glad of the fleece that I had sense to bring.

Earlier, the still young evening had felt very different, the sky buzzing with the calls of swallows and house martins, newly arrived and hawking over the lakes. These birds were probably moving through, a steady procession of exuberant groups following the line of the old river as it meanders towards the fens and beyond. Willow warblers and chiffchaffs could be heard singing from scrubby parts of the reserve, together with more blackcaps than were here when I had last ventured out. Not all of these birds would remain to breed and I suspect that many of the willow warblers would depart soon enough to leave us with the dozen pairs that we normally hold. Some of the chiffchaffs have been here for several weeks and are definitely paired and on territory. It will not be long before they have nests for us to find and monitor.

But that was earlier, that was when I was looking hard, scanning for migrants and searching for nests. Now it is late, too late to be visiting nests but a good time to stop and to take in the landscape. I don’t what it is about dusk that resonates so strongly with me. Perhaps it is the sense of transition from day into night, from a world with which I am familiar towards one that is less well known. I never feel unsettled by the darkness, instead finding its embrace comforting, but it does change the balance of one’s senses. Visual cues are replaced by auditory ones and I become more alert to what is going on around me. There is also, I suppose, the sense of satisfaction; a good day’s work is done and I can turn for home.

As the lights fades, the last brief glow of the daytime sky plays shadow puppeteer to the silhouetted trees. Blackbirds chook nervously in the hedgerows and the occasional pheasant rattles off a loose call. A toad shuffles across the sandy track, heading towards the shallow pools where it will gather with others of its kind. Spring is here and I hope this is the first of many such evenings. 

Tough times for Hedgehogs

It has been a long winter, not just for us but also for our mammals, birds and invertebrates. Some indication of just how late winter hung on this year can be seen in the later than usual sightings of spring’s first butterflies or the delayed arrival of our summer migrants (many of which are a fortnight or more behind what we would normally expect).

Perhaps the best indication of the what effects the winter has had on our wildlife comes from the BTO’s weekly Garden BirdWatch survey (www.bto.org/gbw). Each week throughout the year, the 15,000 participants chart the comings and goings in their gardens of birds, mammals, amphibians, butterflies, dragonflies and bumblebees. This community of ‘citizen scientists’ – as the Americans like call them – provides a fascinating insight into patterns of garden use, both between seasons and across years. The latest results from the survey show, for example, that the emergence of hedgehogs from hibernation is nearly a month later this spring that it was in either 2011 or 2012. Even the cold start to 2010 only saw hedgehog emergence delayed by a fortnight.

Of course it is not just a case of the hedgehogs emerging just a little bit late. A late emergence means more time spent in hibernation, placing greater strain on the energy reserves that were laid down last autumn. It seems likely that there will have been higher levels of overwinter mortality this year, something that may place additional strain on a population that is known to be in decline. It is not known just how many of our hedgehogs die during hibernation but mortality levels among young animals, born the previous summer, is thought to be high. A study in southern Sweden, where winter conditions are more challenging, found that just under a third of young hedgehogs entering hibernation failed to survive through to spring.

Newly emerged hedgehogs will need to feed up, replacing lost resources, before the breeding season starts in late April or early May, with the first young normally born in the last week of May. This year, however, I suspect that births will be delayed, shortening the amount of time that newly independent youngsters will have to fatten themselves up ahead of entering hibernation, something that can begin as early as mid-October. The first individuals to enter hibernation are the adults and youngster may remain active for longer, suggesting that they are still seeking out feeding opportunities and trying to achieve a body weight that will see them through the winter. Let’s hope that the summer is long and delivers good numbers of large invertebrates on which this year’s generation of hedgehogs can fatten themselves up. 

A chilly reception

Perhaps the most surprising sight for me this spring was that of a newly arrived stone-curlew. The bird was sat in a snow-covered stubble field, huddled up against some taller game cover and looking decidedly nonplussed that spring had not followed it north. It was not alone and there were even a few reports of newly-arrived stone-curlews found dead because of the tough conditions. Now, just a few weeks later, things look very different and the warmer weather sees these birds more settled on their traditional Breckland haunts.

The first stone-curlews to arrive normally reach us in late March, having travelled many hundreds of miles from wintering grounds located in Africa. The birds favour nesting sites located in areas with a very short sward and plenty of bare ground. Within Breckland it is the large arable fields with spring-sown crops, like carrots and sugar beet, which are often used. You might think that stone-curlews would be rather exposed nesting in these open landscapes, but they are well camouflaged and easily over-looked. The birds favour open habitats so that they can see the approach of potential predators from some distance. This allows the female to slip quietly off the nest and to leave her eggs secure under the blanket of beautifully marked camouflage.

The stone-curlew is our only representative of a group of birds known as ‘thick-knees’, characteristic of open habitats in arid landscapes. Our small breeding population is concentrated on just two areas, the Breckland of Norfolk/Suffolk and Salisbury Plain in Wiltshire. It has been the focus of considerable conservation efforts, both through habitat management to provide the optimum nesting conditions and protection to prevent the unwelcome attentions of egg-collectors or over-enthusiastic birdwatchers. There is no doubt that the stone-curlew is a striking bird with a quirky appearance. Its hunched appearance and over-sized eyes could be something out of a comic book or children’s cartoon and it is easy to fall in love with this wonderful bird.

The fortunes of the stone-curlew owe much to the landowners of Norfolk and Suffolk who welcome these birds onto their land. Were it not for their interest and careful management then there would be far fewer of these birds breeding here. Many of the landowners also work with conservation organisations to make sure that nesting pairs are monitored, so that vital information on breeding success and population structure can be collected. This partnership is vital and sets a good example of what can be achieved by working together. It cannot be easy having a very rare bird breeding in the middle of a field full of crops, so our farmers and landowners deserve recognition for the efforts they have directed towards this unusual bird. 

Norfolk goes batty

I wrote a column last year about the Big Norwich Bat Project, a study that set out to discover which bat species could be found in and around the city (www.norwichbatgroup.org.uk/project.html). The project has proved to be stunning success, with 85 percent of the city surveyed and some 30,000 records generated. Eleven different bat species were recorded during the survey, including Nathusius’ pipistrelle, a species previously only known from a handful of sites across the county. The project is being run again this year but, additionally, it is also being expanded to cover the whole of Norfolk.

The success of the project is, in a large part, down to the volunteers who ‘host’ a bat detector for a few days. These detectors record the calls of passing bats and store them on a memory card which, once the detector is returned to the survey organisers, can then be downloaded and the data analysed by computer. The detectors are available from 17 different centres located across the county and volunteers can sign up to the survey via the project website (www.batsurvey.org).

Monitoring of this kind is important and has the potential to revolutionise our understanding of bats and their distribution across the county. Our knowledge of bat distribution, particularly for some of the less common species, is relatively poor and this new approach should deliver a far better understanding of which species are present and where. It will also tell us how bat activity is influenced by the weather and with season.

UK bat populations have declined over recent decades and many are still under threat because of our activities. Building and development work, which affects roosting and breeding sites, and loss of foraging habitat, which reduces feeding opportunities, are thought to be particular problems. One of the difficulties in dealing with the problems that are faced by bats is that we have insufficient information on bat distribution and population structure. Knowing where a species occurs and in what numbers are key to successful conservation action; projects like the Norfolk Bat Survey will go some way to addressing these gaps in our knowledge, adding information that will slot in alongside that collect through other schemes that look at roosts and breeding sites.

Equally important is the way in which the Norfolk Bat Survey will introduce many new ‘citizen scientists’ to bats and their study. Being nocturnal, bats are often misunderstood or even feared and work is needed to demonstrate to a wider audience just what fantastic animals they are. It looks set to be an interesting summer for this pilot year of bat recording. If all goes well then it is likely that other counties will follow Norfolk’s lead and more people will get involved with bats.

Un-sprung

It has been just over a week since the weather changed and spring uncoiled herself from the grip of winter, a winter uncharacteristically long and reluctant to shift. Since that Sunday morning, when everything suddenly felt different, the countryside has burst into life. The half-light of dawn echoes to a chorus of bird song. Initially dominated by the songs of resident species like robin, dunnock and blackbird, it now carries the added notes of newly arrived chiffchaff, blackcap and willow warbler. Blocks of forest clear-fell, initially silent, now carry the descending notes of woodlark and tree pipit. It is as if everything had been held back and is now rushing into the breeding season headlong.

Even my small urban garden is full of activity. Both dunnock and blackbird have been collecting nesting material; the dunnock is well on and clearly lining the nest, the blackbird a bit further behind and taking mud to form part of the nest’s core structure. The blue tits have been busy adding moss to the nest box on the studio, seemingly a protracted process and sometimes involving the removal of material viewed as unsuitable. A quick check with my endoscope (a tiny camera on a flexible cable) revealed that the tits have got the base of the nest finished but still have some way to go.

Then there are the woodpigeons, comical in their approach to nest construction. The pigeon pair have been rather haphazard in their selection of sticks and other material for the nest that they are building in next door’s apple tree. Oversized sticks are collected with zeal but then dropped as the bird struggles to add them to the nest. One of the pair even tried to remove a long piece of ivy, still attached to a wall; the bird struggled for a dozen minutes before accepting that this was one tug-of-war that it simply was not going to win.

I suspect that over the next few weeks the pace of spring will continue to increase, as birds shift from nest building through to egg-laying and the rearing of chicks. Everything seems to happen so quickly, as the vegetation unfolds, the insects emerge and the nesting season moves into top gear. It is such an exhilarating time of the year and there is a real sense that new life is being created. In fact, so much seems to be going on that it can sometimes be a struggle to keep up with it all. As someone who spends a lot of hours studying birds and their nesting behaviour, it can feel as if everything is happening at once, the days and weeks quickly slipping by towards mid-summer and beyond.

Sprite of the water

There is a sense that winter is losing her grip, the warmth in the morning sun sufficient to pierce the legacy of last night’s frost. The sky is clear too and the light ideal for photography. There is just time enough on the walk into work to seek out the black-bellied dipper that has been wintering on the river, pulling in the crowds of birdwatchers to the edge of my little patch. It is the presence of these other birdwatchers that spurs me on to visit so early; the selfish pleasure perhaps of having the bird to myself.

The dipper has remained faithful to this one small stretch of the river for several weeks now and each morning I expect it to have gone. It hasn’t though and I am soon crouched close to the bank of a small channel that carries water away from the main river and through a small belt of trees. Just where the channel widens out and deepens slightly into a small pool is where the bird is often to be found. Sure enough the bird is here again this morning, perched on a partly submerged branch and bobbing gently as only dippers can do.

I can feel the warmth of the sun on my back, a welcome feeling given the draining cold of the ground on which I am crouched. The bird is remarkably tolerant of these visits and soon ventures in close, leaving the branch to swim across the water, the head occasionally thrust below the surface as the dipper searches for submerged prey. With a flick of its wings the dipper forces itself below the surface, bouncing back up again with a caddis or some other delight in its bill. Every now and then it blinks, a silver-grey membrane flashing across the eye’s surface; another little detail that is so pleasing to take in.

As a child I always associated dippers with the fast flowing streams and rivers of northern and western Britain. This spot, heavily shaded and with its gentle flow, didn’t appear to fit at first but now seems perfectly suited to this delightful bird. The dark tones of the dipper’s plumage seem to mirror the dark soil of the bank, the wet logs that lie part submerged and the smooth surface of the water, which is reminiscent of deeply polished wood.

This bird has taken on the character of this bit of wet woodland, perhaps giving something of itself in return. I suspect that when the dipper does eventually head off, the wood will seem empty; devoid of its newly acquired sprite the sense of place will feel different and I will look back at my photographs with a sense of longing.

Return of the otter

Water is often the focal point of a landscape and the two rivers that meander their way into the Breckland town of Thetford are a case in point. Once an important crossing point, the area around Nuns Bridges has again brought people from great distances to interact with the river and its environs. Initial interest from beyond the local naturalists and birdwatchers, who keep a regular beat along the river’s margins, was down to the arrival of a black-bellied dipper. This small bird, a vagrant from the continent, had chosen to winter here, feeding from the river and the network of streams that work its margins. It was an unusual visitor and ‘wanted’ for many a bird-lister’s notebook.

Soon, however, visiting birdwatchers encountered the local otters and discovered just how approachable these normally shy creatures are along this section of river. As the weeks have passed so the number of otter watchers has increased, an army of green and camouflage with long-lenses on their cameras and a glint of expectation in their eyes. By and large the otters seem oblivious to this new found audience and they regularly ‘perform’ by fishing, porpoising, play-fighting or by lumbering out onto the bank for a closer look at the growing crowds. Some days I am confronted by the comical sight of a long-lensed cameraman, frustrated by an otter that is too close to his lens to allow him to frame the image properly.

As someone who walks to and from work along the river I have shared the otters with other regulars, a community with a common love of the river and its inhabitants, and together we have felt the joy of seeing these wonderful creatures reclaim their watery realm. There have been otters on the river here since at least the mid-1990s but it is only recently that their numbers have reached a level where individual animals appear comfortable abroad during daylight hours. The origins of these otters stems from the breeding and release work carried out in earlier decades by the Otter Trust. The success of the Trust’s efforts can be seen in generations of young otters born on this stretch of river over recent years. The population is now self-sustaining and access to clean rivers, rich in favoured prey, has been particularly important in the otter population reaching this point.

The otters are normally seen singly, but sometimes two may be seen together. Larger groups, comprised of a female and her dependent cubs, are a less common sight and I suspect that they are more wary in their interactions with the local human population. The family groups can prove particularly engaging, the playful youngsters often chasing one another from water to bank and back. There are times when the group of young otters are in such fluid motion that it becomes impossible to count the number involved.

The arrival of the otters has not been without its problems. The presence of these predators has been blamed for a decline in fish stocks, even though I am unaware of any monitoring work by which such a statement could be supported. No doubt, the local waterbirds no longer have things all their own way, the return of a native predator will mean the failure of some nesting attempts and the predation of some chicks and adult birds. I have monitored a few failed nesting attempts but it has been impossible to say whether these were the result of the otters or of a dog walked off of the lead. More vocal criticism has come from some local residents, however, whose homes border the river. Treasured koi carp have been taken from ornamental ponds and I’ve also seen images of a chicken being taken from a waterside garden. Of course, the responsibility for these losses lies not with the otters but with the residents who have left fish and livestock unprotected. As a nation we have been spared the shadow of dangerous predators and, without wolves or bears, we have become over-confident in our interactions with the natural world. The return of the otters has, for some people at least, forced them to re-evaluate how they keep and manage their livestock.

The otters have not had things all their own way either and I know of three individuals that have been killed by traffic at locations where the river passes under a road. Efforts could be made to reduce the chances of an otter coming into contact with a car by manipulating the banks of the river as it passes under a bridge, making it less likely that the otter will venture away from the river and onto the road. There is also the problem of some people attempting to feed the otters, often in an attempt to lure them into a position favourable for photography. This is clearly an irresponsible thing to do; the otters are wild creatures and we should avoid blurring the lines by offering food in this manner.

The arrival of the otter watchers has drawn attention to the presence of the otters. I have heard it muttered that we should not be promoting their presence and that it would be better if we left the otters alone. However, the sight of a wild otter can be a powerful force for good, strengthening our bond with the natural world and reinforcing messages about the need to look after our rivers so that they continue to support the diverse communities of animals and plants that are associated with them. Yes, some of the otter watchers have been badly behaved; yes, there may be people who wish the otters harm, but in my experience sharing wildlife in this manner strengthens the community’s support and helps to secure its future survival. Alongside this we need to educate those who view the otters as a threat, so that they understand the responsibility they have to safeguard their livestock, rather than simply blaming the otters for doing what is part of their natural behaviour.

The Thetford otters are unusual in their tolerance of human activity and you only have to see them nonchalantly feeding in front of a crowd gathered outside Argos to appreciate this. Their presence underlines that the river is currently in a healthy state but we need to make sure that it remains this way if we are to retain our otters for future generations. These otters are the true denizens of this river, haunting the hollows that have formed under the exposed root-plates of riverside trees and slipping effortlessly between the worlds of water and land. The late Roger Deakin, describing the otter in his wonderful book Waterlog, wrote of the otter’s “puckish, Dionysian habit” and how it would veil itself from view. While the Thetford otters retain this ability, appearing and disappearing with the slightest of ripples, they have become something else too; they are now the street performers whose ‘street’ is a watery one, cutting through the centre of this small market town to the delight of human observers.