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Nature Notes 2019

March 2019: Connections

You know that BBC programme, Only Connect, where brainy panellists have to guess the unlikely connections between quite different words.  Well, here’s a free suggestion for a tricky question: what’s the connection between cows, beetles and partridges?  

Starting with cows, then. Cows have been blamed for a serious contribution to global warming through their massive emissions of methane gas. That comes from both ends, so to speak –belching and flatulence.  Apparently, a cow can produce some 50 gallons of methane a day, and since methane is over twenty times as powerful as the carbon emissions we hear so much about, and there are some 16 million cows in Britain, you can see (and often hear) the scale of the problem.  In New Zealand, which has much more livestock than we do, there was even talk a few years back of a ‘flatulence tax’ to help save the planet.  But I recently read a scientific article with the splendid title, ‘In praise of cowpats’, which makes a rather different point.  Cowpats feed a host of insects.  Masses of flies and beetles arrive within minutes of a fresh, glistening cowpat hitting the ground; these are followed by legions of others as the pat matures, decays and is eventually pulled underground by worms and dung beetles, so contributing to rich new plant growth. Each pat in open pasture produces some 1,000 developing insects this way – so with an average output of six pats a day that’s 6,000 insects a day or over 2 million a year.

And we now know how crucial insects are to the whole chain of animal and plant life.  They pollinate plants, provide food for birds and mammals, and are crucial to human agriculture and food supplies.  It’s been estimated that if all the world’s insects were ever to disappear humanity would only last a few months and the earth would eventually become a vast compost heap, supporting only a gigantic blooming of fungi.  But we also know that insects are themselves under great threat. A recent study in Germany revealed a 75% decline in insects since 1989 – and that was in German Nature Reserves! This is largely a consequence not of climate change but of habitat loss and the pesticides with which we drench the land; and that in turn explains why many farmland birds have declined so sharply. 

Which brings me to the third element in my quiz question: the grey partridge, whose numbers in Britain have declined by a staggering 90% in a single generation.  Wild grey partridges were once common in the East Anglian countryside, but the ones you see around here now tend to be released birds, though there are plenty of red-legged partridges. Now – I’m getting to it at last – the scientific name of the grey partridge is perdix, so called because the whirring sound of a covey of partridge taking flight was thought similar to the natural human process described by the ancient Greek verb perdomaimeaning ‘to break wind’. So there you have it.  Not many people know that. 

 

Jeremy Mynott

16 March 2019 

 

 

February 2019: Changing diets

Did you make any New Year resolutions about diet?  Still keeping to them? Thought not, so take a tip from wildlife.  Some species have remarkable ways of changing their diets to suit the season – and in particular to get them through the winter.  As the days get darker and colder in autumn insects become much scarcer, so blackbirds, blue tits, starlings and other insect-eaters go vegan and switch to alternative sources of energy like seeds, nuts and berries.  A good example for us, if you believe all those diet books.  

But other species take more extreme measures you’re unlikely to want to imitate.  There’s a bird called a bearded tit, for example – a real misnomer, since (a) it isn’t bearded (it has a nice black moustache) and (b) it’s unrelated to the blue tits and great tits you see on your bird-table.  Bearded tits breed in large reed-beds like those at Minsmere and Walberswick, but they range more widely in winter.  I’ve seen them a few times on the Suffolk coast, feeding – rather incongruously – at the roadsides.  What they were doing was swallowing gravel and tiny stones, which they store in their crops to help them crush and digest the seeds they’d been harvesting from bulrush heads.  It’s a sort of DIY grinding machine. Their waists and weights expand accordingly over the winter period.

Shrews go even further.  They can’t hibernate and switch off, but need to feed continuously and therefore have to take quite drastic measures.  The organ that absorbs most of their energy budget is the brain, so they re-absorb that and literally shrink their heads to reallocate resources. The scientific name of this strategy is known as Dehnel’s phenomenon. As a solution to a critical problem it’s a no-brainer, you might say. Come spring, if the shrews have survived, they just grow their brains again. Don’t try this at home, but ‘going to see a shrink’ may take on a whole new meaning for you.

The most extreme solution of all is practised by various moths. The December moth, for example, is so called because it’s one of the few flying at that time of year. But in its earlier form it fattens itself up as a caterpillar, over-indulging as if it’s Christmas lunch every day. And when it later emerges as a plump moth from its chrysalis stage into chilly winter, with no nectar or sap to feed on, it just lives off its accumulated fat … and then dies.  Adults are physically incapable of feeding, so that’s it.  No Plan B and not much of a life, you might think.  But it does at least get to mate and deposit some eggs to ensure the next generation.  Whether as a moth it remembers its happy childhood seems unlikely, but that’s metamorphosis for you.

I think humans tend to put on a little weight in the winter as well – to cheer themselves up and add a little insulation, but you can always revive your resolution and change your diet again in the spring.  Life goes on.

 

Jeremy Mynott

Lavender Cottage

12 February 2019

 

January 2019: Berried alive

HawthornI’ve never seen the hawthorn bushes so laden with berries as this year.  If you walk along the lanes you’ll see the lines of ancient hawthorns stippled in scarlet like a pointilliste painting.  The haw of the hawthorn is the red oval cup, technically called a pome (not to be confused with the acronym P.O.M.E.  ‘Prisoner of Mother England’, originally used of inmates deported to Australia – just in case you’re doing any pub quizzes).  The hawthorn belongs, somewhat surprisingly, to the large rose family, which also includes rowan, blackthorn, damson, apple and cherry, as well of course the rose itself, all of which have similar pomes encasing their seeds.  The word ‘haw’ comes from the old-English haga-berige, meaning hedge-berry, and the trees are an ancient part of our landscapes.  There are more references to hawthorns in the Anglo-Saxon charters than to any other tree and hawthorns are also the trees most often encoded in English place-names, like Hawstead.  But it wasn’t until the parliamentary Enclosures of the 18thand 19thcenturies, when some 200,000 miles of these ‘quick-thorns’ were planted, that they marked the rectilineal geometry of our field boundaries in such abundance.  

In spring, of course, this is the May tree (the only tree that shares its name with a month), and last spring was notable for the billowing clouds of white blossom that graced our hedgerows everywhere.  I met a lady on a walk in Thurlow recently who asked me if I believed the old country saying that a heavy berry crop presages a hard winter. In fact, I fancy that the causation works the other way around, and that the foaming bridal display in spring is now being realised in this wonderful, winter fruitfulness.  I doubt the hawthorn can make long-range weather forecasts any better than the BBC can … 

Any tree as ancient and charismatic as the hawthorn is bound to present itself today not just as a biological species but also as a cultural icon, trailing a comet’s tail of myth, fable and folklore.  The hawthorn’s red berries, like those of the holly, speak of dark rites involving blood and sacrifice. But they can be positive omens, too: Joseph of Arimathea, leaving Jerusalem after the crucifixion, is supposed to have travelled to Britain and struck his staff into the ground at Glastonbury, whence it burst into a sacred thorn tree that has for centuries flowered in the nativity season; and every Christmas a sprig from its descendants is still sent to the Queen as a symbol of renewal.  And these same berries are providing a rich larder for all the winter thrushes – redwings, fieldfares and blackbirds – that have migrated here from northern Europe to escape the hard weather.  Let’s hope these little beasties from the East don’t bring it with them this year.

 

Jeremy Mynott
Lavender Cottage

 

 

 

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