Saturday 30 April 2011

Dinner is unfurled



The sap is rising and all around the countryside things are springing into leaf. Fresh green leaves, often miniature versions still to expand to their full size, see a welcome return of green hues to the landscape. The stark, two-dimensional forms of branches are now clothed and the dry soil beneath shaded by an expanding canopy of life. These new leaves will power this season’s growth, enabling many trees and other plants to lay down reserves that will see them through the distant winter.

This flush of green serves another purpose and is already being eyed by hungry bugs that will chomp, munch and slurp their way through its plump cells. The caterpillars of various moths will be among the most numerous of these eager herbivores. While some will live on the surface, trimming back the fresh growth, other tunnel their way through the soft tissue leaving behind them characteristic ‘leaf-mines’ full of frass (caterpillar droppings)! Caterpillars are not the only creatures to mine the leaves; various sawflies, flies and beetles also make a living in this manner.

Some of these mines will be familiar enough to regular readers of these columns. The Horse Chestnut Leaf Miner has made the headlines on numerous occasions since it first reached our shores. The sheer size of its population on individual trees has turned the entire canopy a rusty brown and there have been calls that ‘something should be done’. It might well be that the population of this particular leaf miner settles down to a more respectable level over time, in much the same way as was the case with the Firethorn Leaf Miner just a few years ago. The mines made by many of the small leaf mining moths tend to be all that we see of the moth, so small are they in size. However, these diminutive creatures, just a couple of millimetres in length, are some of the most beautifully marked and patterned moths, with tufty golds, shining purples and wispy whites.

Some of the other leaf feeders are equally impressive but many adopt more subtle tones, attempting to blend in with their surroundings and avoid the unwelcome attentions of would be predators. Nevertheless, the vast number of leaf feeding invertebrates is a food resource that is fully exploited by nesting birds. Resident tits and newly arrived warblers will feast on this spring bounty, using it to fuel their own breeding attempts. So tightly are some of these birds tied into their invertebrate prey that their breeding success is dependent upon them matching the timing of the peak in their chicks’ growth with the peak in caterpillar abundance. This, in turn, is linked to the timing of bud burst and that first flush of green.

Friday 29 April 2011

Taking a moment


How do you interact with the countryside? Do you use it for recreation? Is it, perhaps, the backdrop to a walk with family or friends? Is it something in which you exercise yourself and the dog? The real question is, ‘Do you ever stop and truly engage with it?’

I know from experience that it is hard to find the time to stop and do nothing, to step outside of your daily life and find a moment when you can become part of the countryside, aware of and immersed in your surroundings. It is something that I don’t do enough, but when I do I find that the benefits stay with me for a long time afterwards. It does require patience and the ability to temporarily switch of thoughts of the things you should really be doing.

The first thing I do is find somewhere off the beaten track, a spot on the river perhaps, the shade of a hedgerow or the middle of some wooded gully. I settle myself down and just watch and listen to what is going on around me. It is the sounds that you notice first, invariably the songs and calls of birds; being able to recognise the different species means that you can soon place the players that make up the soundscape: the distant Chiffchaff, the sweet-sounding Blackbird and the thin song of a Dunnock. Behind these is a deeper chorus; a low, drowsy buzz of dozens of insects, the true background to an English spring. Once you have settled into the rhythm and melodies you then start to pick up other sounds, perhaps the rustling of some small mammal in the grassy sward.

Then you start to pick up movement, your peripheral vision charting foraging birds as they move through the scrubby cover. Now you are settled you become part of the scenery and other creatures pass by unaware of your presence. I have had Munjtac approach to within a foot or so, oblivious to my dappled form, hunkered down in the shadow of a hedge. I have had shrews and, once, a mole, run over me, going about their business at a rate that counters my calm immobility. Very occasionally, if I have not chosen the place of my solitude well, it will be another human being that passes close by, unknowing and blinkered, perhaps deep in thought.

As we have become more divorced from the world around us I feel that our senses have been dulled. With no predators to fear in this pleasant English countryside, our senses are no longer alert to what is going on around them. Taking time out provides an opportunity to re-engage them.

Thursday 28 April 2011

A wdier community


The Internet has brought with it many things, not all of them welcome. What it does provide, however, is access to a wider community of naturalists and the ability to share information on the countryside and its wildlife with like-minded enthusiasts. For me, one of the most useful things about having access to this wider community is that it enables you to get advice on the likely identity of creatures that you have found but been unable to name. Pretty much all of Norfolk’s wildlife has one or more people that are passionate about it and many of these supporters share their passion and knowledge with a generosity that is to be applauded.

The availability of digital cameras, including those on most mobile phones, means that it is relatively easy to take a photograph of some insect and seek an online identification. Of course, not everything can be identified from a photograph and, in such cases, the specimen may still have to be sent off to the expert for identification. As someone who regularly gets asked to identify things, I know that in with the many common species you get asked to identify there will occasionally be something truly amazing, making the effort of identification well worth the effort.

Being part of this online community does not just revolve around sending records or identifications to our network of county recorders. Many naturalists share their experiences online, working collaboratively through projects like i-spot to develop and share their identification skills and to help with surveys and studies. Such collaborative projects are invariably fascinating and, in addition to making a valuable contribution through your participation, you will find that you learn some really amazing things. OPAL, the people behind i-spot, have run surveys looking at earthworms, water quality and lichens – things that you might not have looked at yourself had someone not asked you to do so.

Being able to share your observations with others is rewarding in its own right; in fact, it is one of the reasons why I enjoy writing this column. Hearing that someone has recorded a species, perhaps in a particular location or in a particular week, can prompt you to go out and look for it yourself. Word soon spread around the local network here in Thetford once it became known that our local Otters had cubs and were frequenting the river in daylight. One of the local bridges became known as ‘the Otter Bridge’ and many local residents were seen there each morning and evening, all hoping for a shared glimpse of these sometimes elusive creatures. I met people on that bridge who I now bump into elsewhere, reinforcing that joy of shared community. 

Wednesday 27 April 2011

Summer migrants have started nesting


The onomatopoeic song of the male Chiffchaff has been much in evidence over recent weeks, with birds setting up territories in many of the scrubby habitats around the reserve and out in the forest. They are one of the first summer migrants to arrive but their morning chorus has now been joined by Blackcap, Whitethroat and Willow Warbler. While many of the new arrivals are likely to be passing through and not yet settled on a territory, the Chiffchaffs have had time to get themselves sorted and many will now be paired up. This makes it a good time to go out in search of their nests. Later in the season, when the birds are less obvious and the vegetation has grown up, it will be a lot more difficult to pin them down.

I spent a couple of hours this morning watching one of the local Chiffchaff pairs that I thought was settled and likely to have started building. The nest of a Chiffchaff is like a rather untidy and flattened Wren nest, built low down in tangled vegetation but always just off the ground. Many are built where the tangle of the herb layer pushes up into the lowest branches of some shrub.

The male of the pair I was watching was delivering his chiff-chaff song from a number of perches and it took me a little while to pick up the female. She was working her way through the herb layer, swapping between bouts of feeding and pecking at potential nesting material. Her route brought her towards me and, as I watched her flicking from stem to stem, I began to wonder if the position I had chosen to watch her from was a little too close. The hen reinforced this opinion by uttering her off-nest alarm call, a ‘hueeet’ note that rises in pitch at the end, and by picking up nesting material and then dropping it. As soon as it was clear that she was working a semi-circle around me I retreated back up the track to watch from a greater distance.

This seemed to work; the hen stopped calling and began to feed, soon joined by the male who had come to see what was going on. He then flew up to one of his perches and started singing again, prompting the female to pick up some material and carry it to a tangle of dead stems. She repeated this several times, arriving with new material and leaving empty-beaked. I had found the nest but would leave it alone for another week until she was likely to have started laying her eggs. It will be then that another visit to monitor the breeding attempt will be needed.

Summer migrants have started to nest



The onomatopoeic song of the male Chiffchaff has been much in evidence over recent weeks, with birds setting up territories in many of the scrubby habitats around the reserve and out in the forest. They are one of the first summer migrants to arrive but their morning chorus has now been joined by Blackcap, Whitethroat and Willow Warbler. While many of the new arrivals are likely to be passing through and not yet settled on a territory, the Chiffchaffs have had time to get themselves sorted and many will now be paired up. This makes it a good time to go out in search of their nests. Later in the season, when the birds are less obvious and the vegetation has grown up, it will be a lot more difficult to pin them down.

I spent a couple of hours this morning watching one of the local Chiffchaff pairs that I thought was settled and likely to have started building. The nest of a Chiffchaff is like a rather untidy and flattened Wren nest, built low down in tangled vegetation but always just off the ground. Many are built where the tangle of the herb layer pushes up into the lowest branches of some shrub.

The male of the pair I was watching was delivering his chiff-chaff song from a number of perches and it took me a little while to pick up the female. She was working her way through the herb layer, swapping between bouts of feeding and pecking at potential nesting material. Her route brought her towards me and, as I watched her flicking from stem to stem, I began to wonder if the position I had chosen to watch her from was a little too close. The hen reinforced this opinion by uttering her off-nest alarm call, a ‘hueeet’ note that rises in pitch at the end, and by picking up nesting material and then dropping it. As soon as it was clear that she was working a semi-circle around me I retreated back up the track to watch from a greater distance.

This seemed to work; the hen stopped calling and began to feed, soon joined by the male who had come to see what was going on. He then flew up to one of his perches and started singing again, prompting the female to pick up some material and carry it to a tangle of dead stems. She repeated this several times, arriving with new material and leaving empty-beaked. I had found the nest but would leave it alone for another week until she was likely to have started laying her eggs. It will be then that another visit to monitor the breeding attempt will be needed.

Tuesday 26 April 2011

Fruit flies enjoy bumper spring


Over the past few days there have been dozens of small flies gathered in the corners of the kitchen windows. They seem to spend much of the day walking around on the windowpane, but every so often one will fly off with a slow, almost ponderous, tail-heavy flight. Numbers are most concentrated around the fruit bowl, something that underlines the fact that these are Drosophila fruit flies, small insects with which many students of biology will be familiar. Another name that is sometimes given is vinegar fly and this might explain the way in which they are drawn to the wine glasses over dinner.  It seems that I am not alone in receiving this visitation; similar reports from across the county have been posted on local wildlife forums and the flies have already made it into the local paper.

According to Tony Irwin, writing on Dipterists Forum, most of the flies involved are a species called Drosophila melanogaster but smaller numbers of a related species are also involved. Drosophila melanogaster is an interesting fly because it is one of the most studied organisms in the world, being used as a model subject in the field of genetic research. One of the main reasons for its use in the study of genetics is its remarkably short generation time. At roughly two weeks per generation, this means that many generations can be studied in a short period, allowing the effects of genetic manipulation (e.g. by cross-breeding) to be studied readily in the laboratory. Two additional features of particular use to researchers are that the females produce lots of eggs over the course of their lifetime (some 2,000 according to some studies) and that the males and females are easy to distinguish from one another. Mind you, since the flies are just 2.5 mm in length, you need a magnifying glass to spot the male’s dark abdominal patch and sex-combs. The latter are a series dark bristles on each of the front pair of legs.

Fruit flies have been an important research tool in laboratories across the world. Rightly or wrongly they have been used to study the effects of radiation, with researchers documenting the effects of different radioactive doses on the behaviour and body morphology of subsequent generations. Associated with this wider work has been Cornelia Hesse-Honegger, whose paintings of fruit fly mutations are both amazing and, at the same time, somewhat shocking. Cornelia has also used a similar approach to document the potential legacy of Chernobyl on other insects and plants, charting mutations and deformities that would otherwise be overlooked. Certainly when you are working with such small creatures, you do need an eye for detail.

Fruit flies enjoy a bumper spring


Over the past few days there have been dozens of small flies gathered in the corners of the kitchen windows. They seem to spend much of the day walking around on the windowpane, but every so often one will fly off with a slow, almost ponderous, tail-heavy flight. Numbers are most concentrated around the fruit bowl, something that underlines the fact that these are Drosophila fruit flies, small insects with which many students of biology will be familiar. Another name that is sometimes given is vinegar fly and this might explain the way in which they are drawn to the wine glasses over dinner.  It seems that I am not alone in receiving this visitation; similar reports from across the county have been posted on local wildlife forums and the flies have already made it into the local paper.

According to Tony Irwin, writing on Dipterists Forum, most of the flies involved are a species called Drosophila melanogaster but smaller numbers of a related species are also involved. Drosophila melanogaster is an interesting fly because it is one of the most studied organisms in the world, being used as a model subject in the field of genetic research. One of the main reasons for its use in the study of genetics is its remarkably short generation time. At roughly two weeks per generation, this means that many generations can be studied in a short period, allowing the effects of genetic manipulation (e.g. by cross-breeding) to be studied readily in the laboratory. Two additional features of particular use to researchers are that the females produce lots of eggs over the course of their lifetime (some 2,000 according to some studies) and that the males and females are easy to distinguish from one another. Mind you, since the flies are just 2.5 mm in length, you need a magnifying glass to spot the male’s dark abdominal patch and sex-combs. The latter are a series dark bristles on each of the front pair of legs.

Fruit flies have been an important research tool in laboratories across the world. Rightly or wrongly they have been used to study the effects of radiation, with researchers documenting the effects of different radioactive doses on the behaviour and body morphology of subsequent generations. Associated with this wider work has been Cornelia Hesse-Honegger, whose paintings of fruit fly mutations are both amazing and, at the same time, somewhat shocking. Cornelia has also used a similar approach to document the potential legacy of Chernobyl on other insects and plants, charting mutations and deformities that would otherwise be overlooked. Certainly when you are working with such small creatures, you do need an eye for detail.

Monday 25 April 2011

Two birds in the bush


There was a certain amount of relief the other morning when I finally found out what was going on with our nesting Robins. The saga began six weeks ago; a spot of nesting in the grounds at work revealed a Robin’s nest, complete and fully lined, just waiting for eggs. This was clearly the nest belonging to the pair that spent a lot of time around the entrance gate, the male singing from the avenue of trees and, occasionally, the nearby gate post.

A week later and the nest still sat empty. Curious to see what was going on I used the car as a hide and watched for signs of activity. I soon saw a hen collecting nesting material but, to my surprise, instead of carrying it to the nest, she took it to an ivy-covered tree less than 20 foot distant. I watched her for a while to be certain of what she was doing. Several more loads of nesting material followed, each time the bird was cautious in her approach to the new site, spending a short while in the ivy and leaving empty-beaked. I figured that the building work that was going on next door, and within a few feet of the original nest, had prompted her to give up and to try elsewhere.

Another week later and it was time to locate the second nest. I had a pretty good idea where it was and soon found it, complete with three eggs. ‘Great’ I thought, ‘we are up and running’. As a matter of course, I went to check the original nest and was stunned to find it contained six eggs. Was the female using both nests or were there two females nesting in the territory of the one male ­– a case of simultaneous bigamy. My most recent weekly visit has, finally, revealed that it is indeed two females, since both were sitting on their eggs upon my last visit. The female in the tree popped off the nest and took refuge in the ivy while I checked her nest contents (four warm eggs), while the other female simply peered over her nest cup and looked down at me. I left her alone but will return in a few days to see how she is doing.

Robins are essentially monogamous and are renowned for their territorial aggression so it is unusual to see two females with a single male. It does happen though, as it has done here, the two females maintaining their own territories within the larger territory of the male. It will be interesting to see how the birds fare once there are hungry mouths to feed.

Saturday 2 April 2011

Mistress of the skies


It was Nick who spotted the Peregrine: its sleek, sharp-winged profile, drifting in a shallow dive that took in an extended arc of sky. The metre wide wingspan was silhouetted against the bright blue, the bird itself drifting south and scanning for prey with leisurely ease. This was my first Peregrine over the lakes, though not the first one to be seen here this year. In fact there had been several sightings in recent weeks, most likely of the same bird and hinting at an individual that was wintering and roosting nearby. Such is the range of these birds, however, that ‘nearby’ could easily mean Bury beet factory, a dozen miles to the south.

We’d speculated on the presence of such a bird earlier in the day while scanning some of the adjoining pasture for Stone-curlews or an early Wheatear (we saw neither). A broad scatter of feathers and the remains of a Mallard suggested an act of predation. Given that the middle of a field was an unlikely place for a Mallard to be caught on the ground, we suspected that it might have been taken in the air by a Peregrine. Our sighting of the bird itself now added weight to that hypothesis.

To have a Peregrine around locally shows how far we have come since the dark days of the 1960s, when there were no more than fifty pairs of these magnificent birds in England. The effects of persistent organochlorine pesticides, accumulating up through the food chain, had brought about a decline in the Peregrine population by poisoning both adults and unborn embryos, with DDT additionally reducing the thickness of Peregrine eggshells, which then broke during incubation. The banning of these compounds, coupled with more enlightened attitudes to birds of prey, has allowed the Peregrine population to recover and many former haunts have been recolonised.

You do not need to travel out of the county to see Peregrines any more. A pair of Peregrines is resident on Norwich cathedral and you will often find local birdwatchers on hand to point them out if you happen to wander by and take an interest. The presence of the Peregrines will make things interesting for the many Feral Pigeons living in the city, and the return of a top predator is to be welcomed. Not only is it a sign that our attitudes have changed but it also provides an opportunity for those living within the city to see a truly wild and magnificent part of nature. I felt a surge of adrenaline when I saw the Peregrine drift over the other morning. To see a creature that has such an impact must be a good thing and is to be recommended.

Friday 1 April 2011

A difficult start


It has been something of an inauspicious start to the nesting season for some of our familiar species. Mid-March, the best time to pin down the intricate domed nests of Long-tailed Tits, had started well and we had found five pairs busy building within the space of a few hours. Two other pairs were behaving suspiciously, leaving tell-tale pointers as to where the nest was likely to be built over the coming days. A week later and three of the nests had been predated, most likely broken into by crows or other corvids. The three that were predated were all fairly exposed, perhaps because the vegetation has been slow to green up this spring as a result of the severe winter we have just come through.

That second visit also revealed another two nests and a suggestion of three other pairs we had yet to pin down. There was also a good chance that the birds who had failed so early, and almost certainly before laying any eggs, would have another go, so things may well get back on track. The question of whether the Long-tailed Tits will do as well as they did last year, when all our nests succeeded in raising young, is something that we will not be able to answer for a number of weeks.

The nests of Long-tailed Tits mark the start of the nest finding season for us, although there is always the odd pair of Robins or Blackbirds having a go in town. The tits are fairly easy to watch, and are readily located by their characteristic calls. Once you have found where they are it is simply a question of sitting and watching where they go and what they do. Sooner or later you will see them collecting and carrying nesting material to the chosen site, a site that is invariably well hidden in some thorny bush (ours tend to favour gorse at this time of the year). Once complete, and covered with lichen and spider webs, the nests are surprisingly well-camouflaged and difficult to spot.

Being completely enclosed, the nests are difficult to monitor and so we have recently invested in an endoscope (a miniature camera on the end of a flexible cable and attached to a hand-held monitor), which allows us to see inside the nest to count the eggs and chicks. Being able to monitor these nests, plus those of many other species, allows us to collect important information on productivity which can then be used to alert conservation bodies to any changes in breeding success that might give cause for concern. With just two to three hundred Long-tailed Tit nests monitored nationally our contribution is an important one.