The ecology of bats (Focus - May)
Bats can live up to 30 years. After spending the winter hibernating, bats will now be fully active and feeding. At first light or dusk, on warm dry days, is the best time to look out for them. Some hunt high in the sky while others swoop low over water. The females, which will have been pregnant since the autumn mating season, will set up nursery colonies in May and then give birth to a single pup, usually in June. These pups are very small and, as bats are mammals, will be suckled until they learn to fly and hunt insects for themselves by August.
Although different species frequent different areas, a landscape generally favourable to bats includes varied sites to roost in, such as old buildings, caves, and hollow trees; hedgerows along which to commute to and from foraging areas, woods, copses, lakes, and ponds. This seems to be a rather good description of the Nadder Valley, and it seems to suit bats.
Last year, the South Wiltshire Greater Horseshoe Bat Project carried out a programme of acoustic surveys using bat detectors across 40 locations in the Nadder Valley. Of the 18 bat species found in the UK, they detected 13 species, both common and rare. At the same time, a small stone mine was monitored, and this confirmed that it is used by several rarer bats, including the greater horseshoe bat. These data contribute significantly to the knowledge of bats in the area.
Unfortunately, bat populations declined severely during the last century. In common with most bat species, those found in the UK feed on insects. Given that even a single tiny pipistrelle bat can eat more than 3000 insects in a night, the well documented fall in insect numbers in our countryside is likely to be contributing to this decline. If they cannot get sufficient food in autumn, when they are building up fat reserves to get them through the torpor and hibernation of winter, they will perish. They are also vulnerable to a range of other factors such as loss and fragmentation of habitat, destruction of roosts, and predation.
Bats and their roosts are protected by law, but are still under threat from building and development work that affect the old buildings and trees where they roost or set up maternity colonies.
by Andrew Graham
Mid-March into early April is the time of a “blackthorn winter”: a cold spell when the blackthorn is in bloom. This is perhaps because the combination of different strains of the species and the varied micro-climates of their growing locations mean that you can find blackthorn in flower somewhere for more than a month, during which it is likely that there will be at least one cold spell. Or perhaps it is that blackthorn scrub, with its clouds of flowers at their peak, look like the bushes have been covered with snow.
The small white flowers bloom on short stalks from buds along the spines and do so before the leaves appear. En masse, the bloom provides a welcome early source of nectar for insects. These pollinate the flowers, which then develop the distinctive blue-black sloes.
The tree grows naturally in scrub, copses, and woodland, and is commonly used to form a cattle-proof hedge. It favours sunny positions, and when left uncut can develop into considerable thickets, such as those in the Oddbrook valley. Mature trees can grow to a height of around 6–7m and live for up to 100 years. The deep brown bark is smooth, and twigs form distinctive, straight, side shoots which develop into thorns. Its trunk and stems form a dense wood which is good for burning and straight stems have been used for walking sticks, including the Irish shillelagh.
The foliage provides food for the caterpillars of several moths. The dense thickets provide sheltered nesting sites for birds, which then feast on these caterpillars, and later on the sloes.
The scarce brown hairstreak butterfly lays its eggs on blackthorn. This is the largest and brightest of the hairstreak butterflies, the female looking a gorgeous golden colour in flight. However, in common with other hairstreaks, it is quite a small butterfly and notoriously easy to overlook. They spend most of their adult lives perched in the tops of trees, out of sight, lapping honeydew from the leaves. If you are lucky, you might see a female when she descends to lay eggs, nearly always on blackthorn twigs in hedges or bits of sheltered scrub.
Our knowledge of the local distribution of this butterfly is improving all the time, due to the efforts of a small number of lepidopterists who tirelessly search suitable locations for these tiny eggs. Correctly identified, these are a reliable indicator of presence, although not necessarily breeding success, but gets around the difficulties of spotting an adult on the wing. The population appears to be spreading westwards from the area north-east of Salisbury. As eggs have been found in the vicinity of Grovely Wood, who knows, they may be present hereabouts without being recorded. Eyes peeled this August/September.
by Andrew Graham
Lapwings (Focus - March)
In early March, lapwings return to their favoured place to breed. I can still remember them being such a common bird that their evocative courtship call and swooping flight was well known. Now, their population has declined so much that locally only a few pairs come back to just one field. During the 80's, their ancestors nested in the spring barley sown in 'Three Corner Piece,' a stony small field. But then the fence was pulled down, the field enlarged and wheat was planted so the birds moved on. They were then looked after by the Carter family at Place farm, who would search the maize fields before cultivating around them or who would move the nests to safety. When the Carters left, the lapwings left too, as the fields quickly became unsuitable for nesting. Luckily, at that time an environmental scheme came in, which paid for a ‘Lapwing plot' to be prepared for them annually. At least, they had somewhere permanent safe to breed in the middle of an arable field. Sometimes they would nest off the plot and it would take both myself and Geoff Lambert to find them and put down a marker. But even so, the numbers of pairs were still declining year on year, so I gave them a pond for water and a source of insects. I even cut down some hedgerow trees where crows would perch to predate on the chicks.
As lapwings are long lived (up to twenty years) and the old birds faithfully return each year, a lack of breeding success can go unnoticed for years, until finally, the old birds die and no more birds ever return.
This year, Nick Adams (a local ecologist with a long RSPB experience) has recommended fencing an area of grass to be grazed by a couple of sheep, which will provide the lapwing chicks with insects. Let's hope that works!
All this shows how farming and the countryside has changed even in my working lifetime, and a species which had adapted to a centuries-old agricultural system, suddenly find themselves relics in a hostile environment.
If you want to see and hear lapwings, a good place to go is Winterbourne Downs RSPB Nature Reserve near Newton Tony. The whole farm has been converted to suit the habitat requirements of stone curlews (another endangered bird species), and lapwings just happen to like it too.
by Andrew Graham
Tree husbandry (Focus - February)
Members of the Society have been busy on practical projects recently. Before Christmas, in the parish meadow (behind the Nadder Centre) we planted nearly 150 trees. A number of trees and shrubs were planted in 2013 in the sheltered, south-western, bottom corner of the field. These are established now and are beginning to knit together. The new planting will augment these. Species planted included oak, birch, hawthorn, willow, dogwood, buckthorn, hornbeam, beech and crab apple. This diversity of species aims to make it as valuable for wildlife as well as interesting to look at. Most of the trees were relatively small, bare-rooted plants; planted correctly, these have the best chance of rapid establishment. Each is supported with a bamboo cane and spiral guard for protection while a woodchip mulch around the base will help to suppress weeds and retain moisture. We look forward to them bursting into leaf in the spring.
We also took the opportunity to weed amongst the young hedge line between the community orchard and the skatepark, again applying mulch to help their establishment.
An ongoing project is to lay the hedge which separates the parish meadow from orchard and skatepark. It will involve cutting away some of the existing growth to make the hedge line thicker and more vigorous in the long term. Laying prompts the existing shrubs in the hedge to send up new growth from the base while still growing from the remaining branches that have been laid. This prevents it getting gappy and top heavy and helps the hedge to develop the width which makes it most valuable to wildlife.
In the New Year members were hard at work coppicing in Oysters Coppice Wiltshire Wildlife Trust reserve near Semley. The society will also continue to organise coppicing in the community field in years to come. When coppicing, all the small trees and bushes are cut down to the ground over a defined area. This lets sunlight in and results in a flush of flowering plants for a few years until the cut stumps have regrown and shade returns. Some of the cut material is woven into dead hedges to protect the cut stumps – or stools as they are known – and later more is placed over the stools to prevent deer browsing. Many woodlands in Britain used to be managed as coppices but as the markets for the products that they produced – e.g., hurdles, thatching spars, fence rails and posts – declined so did coppicing, to the detriment of many woods’ wildlife.
by Andrew Graham
Winter can be a tough time for wildlife and while a number of mammal species will hibernate, many birds deal with poor weather by moving to lower ground or even to a different country. The storms and snowfall of December got many thrushes on the move, and in the weeks following there appeared to be many more blackbirds, redwings and fieldfares in the local fields and hedgerows. It is not just the cold temperatures that they are escaping; a blanket of snow will make food inaccessible forcing them to move to clearer land to feed. Redwings and fieldfares will already have travelled from Scandinavia and Russia to find a milder winter and will keep moving to keep clear of the worst conditions. Similarly, there are increased numbers of coots, mallards, and tufted ducks on Fonthill Lake, where they will spend the winter.
This is all normal but what makes things interesting is when there is real dearth of food for birds in their normal wintering areas. This might be because the food crop (for example acorns, beech mast or fruits and berries) has failed or a species has had a population boom after a good breeding season. This is when an irruption can occur, and huge numbers of birds move to parts of Europe where they are not normally seen. A recent example of this was during the winter of 2017/18 when unusually large numbers of hawfinches were seen throughout the UK. They made a rare sight in the beeches around Fonthill Lake and even popped up in Tisbury gardens. This year it seems to be the turn of the brambling to visit us in large numbers, presumably because of a failure of the beech mast crop on the continent. After reaching the east coast in late September, they had soon spread across the whole country and by the end of November seemed to outnumber the chaffinches in some local beech woods. (You can see this movement graphically on eurobirdportal.org).
It has been a particularly poor year for acorns which will hit jays which favour this as their winter food, normally burying thousands in the autumn for later retrieval. They may travel several kilometres from their home range looking for acorns and will be more visible than usual as they do so. But if the acorn supply is exhausted, they too will be on the move. The classic irruptive species is the waxwing, a bird rarely seen in the UK apart from during one of their irruptions which only occur once every 10 years or so when flocks of a hundred or more may be seen. Who knows what this winter will bring?
by Andrew Graham
Holly and ivy (Focus - December)
As Christmas approaches, thoughts turn to decorating our homes for the festive season. Along with spruce trees and mistletoe, the plants I most associate with Christmas are the holly and the ivy. As well as providing decoration and being easy to identify, these common plants are important for our wildlife. Although hollies can live for up to 300 years, they rarely attain a large size. As they often grow in the understorey of woodlands, they can develop quite a straggly form as they seek whatever light they can reach. This slow growth makes the white wood very dense and good for a number of uses as well as the traditional walking stick.
Male and female flowers occur on different trees and are white with four petals. The flowers provide nectar and pollen for pollinating insects as well as a food source for holly blue butterfly caterpillars. These feed on the flowers of holly in spring while those emerging from the eggs laid in summer predominantly feed on ivy flowers.
Younger trees have spiky leaves, but as trees grow and age, the leaves are more likely to be smooth, especially in the upper branches. Unless a female plant has a male sufficiently close by, its flowers may not be pollinated and will not develop the bright scarlet berries that look so attractive against the glossy leaves. These berries are a vital source of food for birds in winter, and small mammals, such as wood mice and dormice and this helps to spread the seeds.
In the autumn and early winter, the fruits are hard and apparently unpalatable. But after being frozen or frosted several times, the fruits soften, and become milder in taste. At this point, favoured trees can be stripped by groups of thrushes which may noisily dispute possession of this food source.
Berries of ivy are also in demand as winter food for birds. They are black and are held in clusters on mature plants which are the only ones to produce the yellowish-green flowers. These bloom in small clusters in late summer when most other countryside flowers are over and so attract many bees and late flying butterflies such as the red admiral.
Ivy is a woody stemmed, self-clinging climber but can also grow as a trailing plant which roots at many points as it spreads. Ivies have enormous value to wildlife, providing all-important year-round shelter and nesting sites for huge numbers of creatures including birds, small mammals and invertebrates. Ivy has long been accused of strangling trees, but it does not harm the tree at all simply using it for support as it climbs towards the light.
As well as its association with Christmas the ivy has a number of symbolic connections. A wreath around the head was thought to prevent drunkenness and it was also thought to be a symbol of fidelity. Newly married couples used to be presented with an ivy wreath and an ivy frond remains a part of many a bridal bouquet today.
by Andrew Graham
Help for garden birds
During the recent cold and snowy spell, the birds have been very grateful for any food left out in our gardens. Fallen apples prove very attractive to several species and rail travellers may have noticed the blackbirds and fieldfares feeding on the fallers beneath the apple tree at the east end of the station platform.
Collecting and storing fallen apples in autumn means that through the winter you can stick them on the ends of twigs in garden bushes or hedges which makes them easy to access for those birds that will normally avoid ground feeding.
They are proving particularly attractive to overwintering blackcaps. These neat grey birds, with a black (male) or chestnut (female) cap, are the size of a goldfinch and worth looking out for, if you feed your garden birds. They are far easier to see now amongst the bare branches than in the spring, when they are more often heard than seen as they sing hidden in the foliage. I have a pair of blackcaps that are regulars in my garden this winter, though the male is dominant. Indeed, on some days I had noticed that very little food was being taken from the feeder. I then saw the male sitting in the nearby hedge, and every time another bird attempted to visit the feeder, he flew out and shooed them off. He seemed to do this for hours on end for a couple of days, but has now reverted to a more collaborative approach. Perhaps he was just being so protective while it was really cold.
By Andrew Graham
Photo: Avocets (Izzy Fry)
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