Saturday, 10 February 2007

Have Badgers moved in?

The spoil heaps outside the old foxes earth have grown in size over recent weeks, a sure sign that new tenants are in place. The loose sandy-coloured soil spills from these heaps down the steep leaf-strewn slope and into the dark waters that sit silently below.  It is an odd location, positioned as it is at the top of a crumbling slope that eats its way into a small block of woodland. Well-worn paths lead away from the five different entrances, along the very top of the slope and into the wood itself. Not wanting to approach too closely, I can only scan the compacted soil of the entrances with my binoculars, but this fails to reveal a clear footprint that would identify what creature has taken ownership.

The entrances themselves have been enlarged quite considerably and the weak winter sunlight shining directly into one of these is sufficiently strong to reveal that the tunnel remains wide even as it disappears underground. Could it be that badgers have taken ownership? There have been occasional sightings from nearby over recent years, so perhaps this is a sign of a resurgent badger population, expanding into new areas. Norfolk does not hold the number of badgers seen in more southerly or westerly counties. In fact, there are relatively few active setts, though this is changing slowly for the better. Badgers prefer loose, free-draining soils for their setts and need to be near arable land or grassland where they can forage for food. Many areas within the county are too low-lying but some parts are both suitable and well-used. This particular spot is relatively free from disturbance so may have proved attractive to the badgers. Our understanding of Norfolk’s badgers is improving, mainly due to the efforts of Tony Vine and John Crouch who have championed these wonderful animals, spending many hours searching for and documenting active setts. Other records are sent to me, as county mammal recorder, and relate to badgers involved in collisions with traffic on our increasingly busy roads.

A quick search through the wood, following the obvious paths that radiate out from the potential sett, reveals evidence that bedding has been dragged towards the entrances but there is no sign of the shallow pits containing badger faeces, known as badger latrines, that I would expect to see. Since these have a social and territorial function it may be the wrong time of year to come across them. Although badgers do not undertake a true hibernation, they do reduce the levels of activity during the winter months. This suggests that I will need to return in spring in order to find out if it really is badgers who have taken up residence.

Friday, 9 February 2007

Take on the challenge

The British Trust for Ornithology (BTO) and the BBC have just launched a major new project, seeking to follow the fortunes of our nesting birds. Called “The Nestbox Challenge” the scheme forms the centrepiece of this year’s National Nestbox Week (an annual event initiated by the BTO and Jacobi Jayne). Tradition has it that songbirds pair up on February 14th and National Nestbox Week, running from 11th-17th February, provides the focus for a host of nestbox-related events up and down the country. Many of these events are being coordinated by BBC local radio or television and are geared towards children, often providing the opportunity to build your own nestbox.

The Nestbox Challenge itself is what the Americans would call a “Citizen Science” project, where you (the “citizens”) collect information that can make a valuable addition to our scientific understanding. The Challenge is an online survey (visit to access the survey), so you will need a computer and access to the Internet. In addition you will need a nestbox – either one that is already in your garden or a new one that you have just put up. I have already visited the website to register the robin nestbox in our garden and found the whole process very straightforward. Asked to enter some basic details about my garden, such as where it is, how big it is and what sort of plants it contains, I could then log details about my robin box. Once I had entered this information, I could then view its location by using a built-in satellite view of the earth. Now all I need to do is keep an eye on the box, watch to see if nesting birds are using it and then log the details of how the nest is progressing. Guidance is given on how to monitor the nestboxes without disturbing the nesting birds and what information is needed by the researchers.

It is hoped that results from the Challenge will enable researchers based at the BTO to examine the nesting patterns of familiar species like blue tit, blackbird, robin and spotted flycatcher, and to find out how nesting success may be influenced by location, garden type, the presence of predators (like cats) and weather. Understanding such interactions is important if we are to determine the effects of a changing environment (and climate) on our wildlife. The project also serves to engage people with wildlife, providing you with an opportunity to discover new things. Being part of an army of citizen scientists also means that you are making a valuable contribution to conservation science within Britain. So go on, put up a nestbox (or register one already in place) and take the Nestbox Challenge. 

Thursday, 8 February 2007

Centipedes shake a leg

Rooting about the other afternoon amongst some fallen timber, I disturbed a veritable mass of centipedes. Each was just less than three centimetres in length, rich chestnut brown in colour and equipped with sufficient legs to exhibit a substantial turn of speed. No sooner had I registered the presence of this throng of centipedes than they had erupted in all directions fleeing from my intrusion. I have always been a little wary of centipedes; a childhood trait that I have never quite managed to overcome. As with so many childhood fears this one is unfounded, since centipedes only rarely bite humans and even when they do, the sensation is reputed to be little worse than that delivered by a stinging nettle. In fact, centipedes are overwhelmingly beneficial. They are fearsome predators of slugs and insects larvae, making them a true friend of any gardener. While their bite has little effect on us, the powerful poison it delivers is more than adequate to overpower a range of invertebrate prey.

So far, more than 50 species have been recorded in Britain, belonging to two main classes of centipede. First there are the “runners”, surface-active predators like those I had uncovered in the timber. Then there are the “crawlers”, subterranean species that make a worm-like living within the spaces that form between particles of soil.  Although the name centipede means “one hundred feet”, many species have fewer than this, while some have more. In fact, some species hatch from their egg with just four pairs of legs, gaining more pairs with each of the moults they must undergo before reaching adulthood. One of our most familiar species starts life with seven pairs of legs and ends up with 15 pairs as an adult. The species are equally variable in their behaviour. In some species an adult female will show a high degree of care for her brood of youngsters, wrapping her body around them to defend them from predators. Other species simply abandon their eggs and leave the resulting young to take their chances.

Being long and thin has its disadvantages and, with the jaws positioned right at the front, some of our longer centipedes are vulnerable to attack from the sides or the rear. To overcome this threat, some species exude a fluid from their back legs if attacked. This fluid is distasteful to would-be predators like ants and they soon abandon their attack. Other species, notably the soil-dwelling crawlers, can secrete copious amounts of sticky glue from glands along their flanks. This glue is sufficiently strong to bind together the jaws of a predatory beetle for several hours, providing more than enough time for the centipede to make good its escape. 

Wednesday, 7 February 2007

Hair trigger mouse traps with teeth

Stoats and weasels are two of our most widely distributed mammal species, familiar to most but only rarely seen well in the field. Their small size, use of available cover and energetic manner mean that the typical view is of one dashing across a quiet country lane with an arched-backed gallop, in the case of the stoat, or as if on tiny wheels, in the case of the weasel. These two carnivores are beautifully equipped for the pursuit and capture of their favoured small mammal prey. The small, almost cylindrical bodies and short legs enable them to chase small mammals into their burrow systems. The degree of efficiency associated with their ability to hunt small mammals even led one researcher to refer to them as “hair-trigger mouse-traps with teeth”, a suitably apt description.

Both species have long fascinated me. First introduced to them through a gamekeeper friend, I enjoyed many encounters with both species when I spent three years live-trapping small mammals on a north Norfolk estate. Part of my study site was well used by at least one stoat and he would sometimes stand on his back legs and stare at me intently from a short distance away. Even closer encounters were achieved with the local weasels, some of which got into the habit of entering my small mammal traps. My normal procedure for emptying these involved tipping the contents into a clear plastic bag so that the mouse, vole or shrew could be aged, sexed, weighed and marked before being released. Dropping an unexpected and angry weasel into such a bag is not something I would recommend! One such individual stood at my feet and berated me for several minutes upon release and, despite it’s tiny size, was actually rather intimidating.

Stoats may be equally intimidating and are commonly believed to mesmerise rabbits, reducing them to dithering and helpless wrecks, before delivering the killing bite. Examination of rabbits killed by stoats does reinforce the view that some of these victims have literally died from fright. Another curious behaviour associated with both stoats and weasels is the manic somersaulting and leaping about that is sometimes witnessed by observers. Some have suggested that this behaviour is either a form of play or is a trick to catch overly curious prey. However, it may actually be linked to a parasitic nematode worm that goes by the tongue-twisting name of Skrjabingylus nasicola. This bright red worm occupies the sinus cavities of a fair proportion of both species, causing damage to the skull and, potentially, the brain. It could be this that, through irritation, causes the “dancing”. Curiously, the worm spends part of its life cycle in small mammals, further strengthening the link between predator and prey.

Tuesday, 6 February 2007

Old brown is doing well

One of my most enduring memories is of sitting at the window late on a winter’s night, the landscape so strongly illuminated by a bright moon that I could see the detail in the fields and hedgerows. Cupping my hands together and blowing into them through slightly spread thumbs I mimicked the wavering hoot of a tawny owl. Moments later an owl responded, initiating a conversation that lasted for many minutes. Even now, the call of a tawny owl sends a shiver through me. The sound is so strong and evocative it rekindles old memories and re-emphasises the stillness I enjoyed, living, as I did, in the middle of the north Norfolk countryside, away from the drone of traffic and noisy youths of our towns and villages.

It is welcome news then, that the tawny owl population seems to be doing rather well, giving every indication that this enigmatic species will continue to call across our countryside. Results from a new survey of tawny owls have highlighted that, contrary to certain recent suggestions, the population has changed little since the last survey in 1989. Perhaps we should not be surprised by this news. After all, the tawny owl has proved itself to be an adaptable species. Although predominantly thought of as a bird of deciduous woodland, the tawny owl has exploited the opportunities provided by the large tracts of land now under conifer plantation. It has also moved into the built environment, where its catholic diet has expanded to take advantage of roosting house sparrows, brown rats and earthworms taken from garden lawns on wet nights.

The tawny owl is the first of our owls to lay its eggs each spring. According to information collected by the British Trust for Ornithology’s Nest Record Scheme, on average the first egg is laid on the 25th March. By the time that our barn owls are starting to lay their eggs, tawny owls will already have young in the nest. Such early nesting is reflected in the pattern of calling behaviour. Adults are at their most vocal when establishing breeding territories during the early winter. Once the pattern of territories becomes more rigid, the level of calling falls. Later in the year, once the chicks have fledged, they can be heard begging for food from their parents and, once independent, they will call as they establish territories of their own. By calling at night, when few other birds are vocal, the tawny owl has drawn our attention, though not always in a good way. Hearing a calling owl was once considered an ill omen and as a consequence they were heavily persecuted. Fortunately, things now look much better for the old brown owl.

Monday, 5 February 2007

Piggy in the reeds

The winter landscape feels open; last year’s growth is now brittle beneath my feet and the chill of the wind cuts into my exposed flesh as sharply as the dry reeds that edge the narrow path. Summer’s green and lush vitality, expressed through the aromatic growth of fenland plants, has been replaced by the crisp bleached browns of umbellifer stalks, now dead, and wind blown branches. Other than the sound of the reeds being pushed against one another by the wind, there is little other noise. For a few brief minutes I am treated to the twittering calls of a tit flock as it moves through the alders in search of food but even these birds do not linger.

Then, quite suddenly, I hear it; an abrupt whistling squeal reveals the presence of a water rail. It is close-by, ahead of me in the reeds but hidden from view. This retiring bird, with its repertoire of grunts, squeaks and squeals, is one of the real characters of the bird world. Seen well, it is possible to appreciate the mix of colours that adorn this clown of the fens. The rich brown back, streaked with black and the soft grey of the neck and breast may seem plain enough but the zebra-striped flanks, red eye and red, slightly down-curved, bill add a sense of showmanship. Still, this is a reclusive clown and is more often seen, if seen at all, disappearing into the reeds with a flash of its white undertail coverts and a smooth swift gait. This gait has given rise to the local name “skittycock” in some parts of England ­– the word “skit” originally meaning to move lightly and rapidly ­– but it is the water rail’s calls that give rise to a more lasting name, one that has its origins in Norfolk. During the 1800s, when water rails and their eggs appeared regularly on the stalls of Norwich market between March and May, it was known as a “sharmer”. Since then, this name has been adapted to refer to the piercing calls uttered by the rail, reminiscent of squealing piglets, and known widely as “sharming”. It is this name that appears in the textbooks.

It is during the winter months, when continental immigrants join our resident birds, that you stand your best chance of seeing a water rail. If temperatures fall below zero, freezing over favoured water bodies, then water rails may be forced from cover in search of food. At such times they may also supplement their largely insectivorous diet with carrion or fresh meat, the latter sometimes taken in the form of small birds stabbed or grabbed and drowned. A clown with a sinister side?