Nature 2007 August

B, Ef(t) and J – Just one Small Spoonful Of Nature’s Alphabet Soup

I start this month’s Notes with a maths question. What is the next number in the following sequence: 91: 85: 45: 1: 149: 74? Not even Stephen Hawking could compute the answer when I wrote this, but by the time you read this it will be no longer a mystery as these are the monthly rainfall figures in mm that fell chez nous each month this year and the next number will be the July total. The media would have you believe the unpredictable weather we are experiencing this year, reflected in these rainfall stats, and the floods in various parts of Britain provide a trite explanation that global warming suddenly taking a grip. Well I’m sorry to disappoint these ill-informed hacks but the amount of rain this year is not the only reason for the floods which is more to do with the rain last year not this raising the water table exacerbated by houses being built on flood plains without sufficient thought being given to loss of run-off areas, sewers and flood relief schemes. Thankfully, for us in the Chilterns the height above the surrounding areas and the chalk geology provide a natural drainage system or we too could be seeing water lapping at our doorsteps. What surely is an indicator of climate change (or maybe just plain insanity) has been the depositing of neat little piles of road salt on 29th June by the County Council. Beware an arctic winter is clearly imminent.

One of the last birds we have seen fledging this year has been a family of Jays. Like their cousins the magpies and crows they’re not inconspicuous and their intimidating behaviour and habit of robbing nests cause other birds to be on edge. Their Latin name is Garrulus glandarius, which says it all. The first of these two words coined by Linnaeus was derived from the fashion to keep the bird as a pet due to their ability to mimic everything from cats and lambs to cockerels and even the sound of a saw. The second word refers to the acorns, which they have a habit of secreting away in September for consumption over the food-starved winter months. Jays are mischievous but clever birds and possess an excellent special memory and use landmarks in the woodland to locate the acorns they secreted away 3 months earlier. No one is infallible and the acorns that survive the recovery programme contribute to the successful dispersal of oak trees through Chiltern woodlands. Another intelligent bird is the sparrowhawk. The abundant smaller birds start to feed on the insects that congregate on ripening fruit including many of the wild bees collecting sugars to feed syrup to the larvae. The ‘hawk stakes out a likely patch and waits for its chance to swoop.

Meanwhile another potential prey tries to be overlooked. The Harvest mouse, our smallest rodent, weighs in at no more than a 20p piece. Uniquely in Britain it has a prehensile tail and can balance on a stalk of grass. Its signature habitat as described by Gilbert White who first recorded them in fields around Selbourne in Hampshire, is a cereal crop where it makes a tennis ball-sized nest below the thick canopy of the ripening seed. More and more these miniatures of the mammal clan are finding richer pickings on motorway embankments.

With all this talk of water it is an opportunity to encourage a closer look when out and about of the many ponds around that make an important contribution to the ecology of the area. We owe the existence of local ponds to two main factors, one natural and one due to man’s influence. Despite the prevalence of chalk we owe the abundance of small ponds in the area (I can immediately think of a dozen or so) to pockets of clay overlaying the chalk, the same clay that supports brick making, past and present. But think also where the ponds are to be found, as this is a clue to their survival today. Most are adjacent to roads and if not originally dug or enlarged for the purpose would have been the source of water for livestock, cows, sheep and horses. A photo from the early part of 20th century of Pallett’s Pond on Cholesbury Common, beside the road to Wigginton, clearly shows the track made by animals as they walked into or through the pond. Additionally, there must be further dozens, natural and man-made, in gardens and fields. Over the past 100 years 75%, or 1 million, ponds have been lost in the UK so those that remain plus those that have been created are crucial for the 60% of British wildlife that rely on fresh water for survival. Look out for pond skaters and whirligig beetles, both good indicators of a healthy pond. Skaters use their middle pair of legs to propel them across the water surface staying afloat thanks to thousands of tiny hairs on the base of their feet. From June onwards this year’s frogs and toads have been leaving ponds and can appear almost anywhere damp. Whilst in transition they make easy prey for the early morning grey heron. The distinguishing features of these amphibians are the smooth skin of frogs compared to warty skin of toads; frogs have two ridges along the backs whilst toads backs are flattened. Toads walk while frogs tend to hop. There are three species of newts in the UK; Great-crested, Palmate and Smooth. In their early stages they are known as efts. During summer months they feed voraciously ahead of leaving the water in October to hibernate. Common sights overhead are the Blue-tailed and Blue damsel flies as well as the Banded damoiselle with its characteristic flight showing off its black wing bands.

There are 33 native British trees (excludes imported and hybrid trees). Of these I suspect around 20-23 will be found in this part of the Chilterns (at least 19 can be found on the Commons). Some of the rarer and more unusual for the area to look out for are Black Poplar, Large-leaved Lime, Wych elm. It will be interesting to see how they fare this Autumn but given the high water-table there could well be a grand display.