Saturday, 18 August 2012

Patterned plumage

The local blackbirds have successfully fledged another brood. The tropical-sounding chirps of the youngsters have been evident for several days now, even if the birds themselves have not. The parent blackbirds divide their efforts between the offspring, each chick most likely tucked up in cover somewhere around the garden, having just left the nest. The calls attract my attention and one hopes that the local cats are elsewhere at this critical stage.

It was only this morning that I saw the chicks for the first time, now developed enough to venture from cover to seek food around the bird table and from the large border in which it stands. It is clear that these youngsters have a lot to learn. Instinctively, they seem to peck at everything, swallowing some items that I cannot imagine would prove edible. So long as they don’t prove to be toxic no harm should be done. The adults look fatigued, their plumage tatty and suggestive of a long and difficult season. I suspect that this will be the last brood of the year for these birds and I wonder how many chicks they have managed to get off since the first nesting attempt, made many months ago.

Other blackbird youngsters have already started to moult through some of their body feathers, the warm gingery browns of youth being replaced by the more sombre feathers of adulthood. These young birds look most peculiar, like a parlour game in which two different species have been spliced together to form some new creature. It is easy to see why they cause confusion among those just starting out with birdwatching; such intermediate plumages are often absent from field guides. The same thing happens with young starlings which, part way through their moult, are neither one thing nor the other.

Most young birds will have left the nest with their body plumage not fully developed. All the effort has been directed towards attaining a size at which the chick can leave the nest and fly. In the warmth of summer the full complement of body feathers can wait a few weeks. Once the chick has become safely independent then it can add the extra feathers in preparation for what lies ahead. For these young blackbirds the future is likely to be a winter spent here in Britain, perhaps with some local movement out of town to feed on autumn’s bounty and a period of dispersal to where, next year, they will set up territories of their own. For other birds, like the nestling swifts, the future holds a staggering journey south, to wintering grounds that stretch beyond the equator. The next few weeks will be critical, as preparations are fine tuned and journeys begun.

Friday, 17 August 2012

A forest palette

The patches of clear-fell are coming into their own now. Several seasons on from when the conifers were harvested, the ground cover has now developed into a sward that, although dominated by grasses, contains a diversity of colours and forms. The sward’s colour palette is definitely slipping towards autumn though, the flowering grass heads now faded to take on pale golden hues. Here and there the rich yellow of ragwort stands strident, balanced by the pale blues and soft purples of vipers bugloss and vetch.

Although the sward looks dry and brittle, it is still heavy with moisture from overnight rain and my trousers are quickly soaked, much like the dogs that follow at my heel along the narrow track that snakes back towards the road. The strong, almost acrid scent of a fox hangs on the air, proving that it is still around even though I have not seen it for several weeks. The dogs note its passing too, an audible sniff as two heads drop to the ground and cast around.

A moth, pale in colour and heavily worn skips up from the path before I can identify it and is away across the broken ground. In the distance, a line of beech fringes the road, a veneer of deciduous woodland in a landscape dominated by regimented lines of conifers. Beneath the beeches it is dry, there is no sward here despite the thin canopy that casts a soft green light onto the ground below. I like these beeches; they remind me of home and of the great beech hangers of my youth. The silvery-grey trunks reach up towards the canopy and the spacing of the trees gives a sense of being inside some airy outdoor cathedral. This sense is heightened by the stillness of the air and the early morning calm: no traffic, no planes and little bird song at this late season.

Even though I rarely vary my route, these early morning walks seem ever changing thanks to light, season and weather. You get a real sense of place by visiting the same site over time, learning its changing moods and responding to them subconsciously. Right now, the forest is calming and there is a sense of timely transition from summer into autumn. The forest smells autumnal and the early morning mist, an increasing feature of these autumn mornings, hints at the days that lie ahead. Some say that we’ll get an Indian Summer, one last hoorah to round off a summer of celebration, but I am not sure that it will feel right. The transition from summer to autumn is a gradual process and, judging by how the forest feels, it has already started.

Thursday, 16 August 2012

The doctor fish

I used to fish as a boy, mostly bobbing a little bubble float down one of the local streams to catch trout and gudgeon. One summer, however, a school-friend secured access to a private woodland lake, well-stocked but rarely fished and it was there that I caught my first tench. Even though I have not been fishing for years, I can still remember the cool muscular body, enveloped in mucus and the characteristic smell that lingered on hands and clothes long after the fish had been released back into the dark, reflective waters.

Although I cannot remember the weight of those tench that I caught that summer – for me, the fishing was never about catching the biggest fish – they were a fair size and felt solid in the hand, even though they lacked the raw muscular power of a game fish. Their docile nature, they pulled on the line but never really fought, fitted with the heavy air and quiet surroundings of that shaded pool and it is perhaps unsurprising that I always associate the tench with that particular place. Their soft, olive-brown colour also seemed in keeping with the woodland surroundings.

The tench is a fish of slow-flowing rivers and stagnant pools with muddy bottoms, where it can tolerate low oxygen conditions. It can even survive out of water for several hours, provided it is wrapped in something moist. Here in Britain it is regarded as a sporting fish, though less popular than carp – presumably because it does not grow as big. Elsewhere in Europe, however, it is caught for the table and cooked in a similar manner to carp. The flesh is dark and reputed to have a strong flavour not suited to all palates and perhaps derived from its bottom-living lifestyle. The Romans, for example, saw it as a dish for the ‘common people’ preferring other delicacies for their own higher tables.

The mucus is said by some to have healing properties, hence the name of ‘doctor fish’ that is sometimes given to the tench. The mucus and the small, deep-set scales - which were ground into powder - were used by physicians for the treatment of various ailments over several centuries. I can’t say that I ever put the mucus to the test, though I do remember that it caused consternation to my mother, who had to wash my ‘fishy’ clothes after a long day’s fishing.

Those school holidays are long ago now and I do sometimes think that it would be nice to see a tench close up again, to sniff that smell that would transport me back to those lazy summer days and the wiping of mucus-covered hands on to once clean trousers.

Wednesday, 15 August 2012

In praise of rat tails

The other week, a fellow wildlife gardener tweeted her delight at attracting rat-tailed maggots to her nettle feed. It might seem an odd thing to be delighted about but not if you are a gardener and happen to know what these unpleasant-sounding creatures turn into. Rat-tailed maggots are the larval stage of certain hoverflies and hoverflies, as any wildlife gardener will tell you, are considered to be great allies in the garden.

Looking rather, well, ‘maggot-like’ these larvae get their name from the long breathing tube at their rear. A number of different hoverfly species produce larvae of this form, including the familiar drone-fly Eristalis tenax, which (as an adult fly) mimics a bee. In some species the ‘tail’ can be several centimetres in length, allowing the larva to remain hidden in the detritus that gathers at the bottom of a pool while still enabling the larva to take air from the surface. rad-tailed maggots are typically found in stagnant water, such as that which forms in farmland ditches or garden water troughs. Others make use of slurry, rot holes in trees and sap runs; it is easy to see how nettle feed emulates some of these peculiar habitats.

Not all hoverfly larvae live such a damp existence though. Some live under bark or within dead wood, while others live on the surface of plants where they hunt aphids – something which may seem surprising for a maggot-like creature lacking legs. It is these aphid-eating larvae that are really the gardener’s friend, rather than the other species that have no impact on potential pest populations. There are even some species that, dare I say it, feed on plants! Each of these larvae tends to show adaptations to its particular way of life. Aquatic species, for example, may have modified mouthparts that enable them to filter feed and to take organic matter from the ‘soup’ in which they live.

Quite a few species have larvae that are similar in appearance so that, even with a guide (believe it or not there is a field guide to these creatures) you have to rear them through to adulthood in order to find out what you have been looking at. I am not quite sure that I am ready to have a go at those species that live in manure or slurry but I think I could manage some of the stagnant water or dead wood forms. It is amazing to discover this part of the hoverfly lifecycle and to find creatures making the most of the opportunities that these rather unusual microhabitats provide. It is also amazing to see the adult hoverfly and to know just how very different things were when it was a larva.

Tuesday, 14 August 2012

Transition to evening

The swifts deliver stereo, a whole performance played out in the evening sky above me. Each scream, high-pitched with a rough and rasping edge, whizzes over and away at speed. The sound enters one ear, builds and then passes to the other like some carefully crafted accompaniment, best heard through headphones. Looking up from my book I see them, many more birds than the occasional drawn-out scream suggests; tiny, black bodies that scythe through the air on wings that beat rapidly and then solidify from blur to the solidity of a fixed-wing glide. Every now and then a group of these rapturous dogfighters wheels over in a low arc and I hear the rush of wind on their wings.

Five swifts blast onto my sky canvas from behind the towering of the next-door semi; a sudden jolt of noise that makes me jump in my seat, so sudden is the appearance. As they bank they flash from black to silver like shoaling fish in a vast ocean that stretches away to the deepest blue.

Even here, not far from the centre of town, there is a stillness that descends with evening and with it the sense that the transition from day to night is approaching. The air feels heavy and moist, the dry drones of daytime insects replaced by the flutter and whirr of the first of night’s moths nectaring on the flowers around me. Occasional noises from the back of the border suggest that larger creatures are also stirring, perhaps the wood mice that abuse my shed, raiding the bird feeders and amassing a winter store amid my carefully-arranged clutter.

A nearer movement gives the sense of being more lumbering than the skittish movements made by mice and I watch its progress as the moving vegetation points to a likely emergence at the border’s edge. Soon the source of the sound appears; a toad, replete and welcome. May he have a productive night feasting on the slugs that plague my tender flowers and vegetables.

By now my book lies face down on the table, the light faded to a point where reading is no longer possible. My ears pick up the sound of a feeding bat, the high-pitched echolocation calls still registering on my ageing ears. Every now and then I catch a glimpse of it as its silhouette flicks across the sky. It looks like one of the brown long-eared bats that catch yellow underwing moths and then carry them to the shelter of the passageway. There they will perch on the wall and remove the wings before munching noisily through the moths succulent body. It is time for me to head inside and tackle the final chores of the day.

Monday, 13 August 2012

Look up!

Lift your gaze above the horizontal, directing it towards likely spots as you wander through town, and you will soon discover that there are nesting woodpigeons everywhere. Two of the houses on our street, for example, sport climbing plants that trail the outline of the front door and in each of these, wedged just above the frame, is a nesting pigeon. There are another three nests along the high street, two in trees and one on the top of a metal cage that protects some passageway lighting from the mindless attention of the local hooligans. There is even one in my garden, a bulbous platform of sticks, formed from the combined nests of three previous seasons and many previous nesting attempts. On top of each nest sits the plump and unmoving form of a woodpigeon.

Many of these nests go unnoticed; despite their bulk the sitting birds are usually silent and many of us wander around with our heads down, watching the pavement or avoiding the gaze of passers-by. This is good news for the woodpigeons, incubating their two eggs or brooding young chicks. Not all of the sitting birds will be on eggs or young, however, as the two members of the pair may take turns at sitting on the empty nest in the days leading up to when the first egg is laid.

It might seem odd that woodpigeons only lay two eggs, but it is a feature characteristic of pigeons and doves more widely. Both parents take turns at incubation, the female incubating for roughly 18 hours in every 24, the male the remainder. The birds switch over at or near the nest so the eggs are rarely left uncovered for long.

One curious aspect of woodpigeon reproduction is that the young pigeons are initially fed on crop-milk, something that is known from very few bird species around the globe. Crop-milk is a secretion that is produced within special glandular cells in the crop wall. These cells become filled with a cheese-like substance and, when full, are sloughed into the crop from where they are fed to the young by regurgitation. The sloughing does not happen continuously and there appears to be a trigger that causes the cells to be released en masse just prior to the time at which the young are due for a feed. Feeding visits to the young decrease with age, the diet also switching from crop-milk to other material, so that older chicks may only receive feeding visits twice a day. This may reduce the risk of an adult being followed back to the nest by a predator and less activity at the nest also makes them more easily overlooked by us.