December 2017

As I write this, the weather has taken a relatively sharp turn as we moved from autumn to winter.   The temperature has dived from a relatively mild 15°C to a decidedly chilly 5-6°C.  This has the effect of driving many of us indoors, venturing out only when fully wrapped.  One insect that also likes to be indoors is the common green lacewing.  The lacewing overwinters as an adult (as opposed to hibernating as an egg or caterpillar) and if it can, it will find a way inside your house where it is warm and cosy and safe from predators.  Once inside your house, a remarkable change takes place – it goes from bright green to a delicate pink colour.  Just why this should happen is unclear – perhaps it is better camouflaged that way despite your choice of décor – but in the spring it will turn back to its natural green colour.  In the wild, lacewings hibernate naturally under leaf litter or in other rough and untidy places you may have in your garden, so perhaps pink is less conspicuous in such places.

Common green lacewing - Chrysoperia carnea

When your lacewing leaves your house in spring it will find a mate and very quickly lay a batch of green eggs.  The eggs also change colour to grey before the emergence, in a few days, of the lacewing larvae.  These are one of nature’s most voracious predators and will eat the larvae and adults of many different species of insect.  Aphids are one of their favourite prey insects and they will chomp their way through a greenfly infestation in very short order.  When I say chomp, that is not quite accurate as they have no biting mouthparts.  Instead, they adopt a similar technique to spiders by injecting their prey with digestive enzymes and sucking out the resultant ‘soup’.  Their appetites make them popular with farmers and gardeners who can buy lacewing eggs as a non-chemical pest control.  (You can even buy them in batches of 1000 from Amazon!)  Once they have cleared your rosebush of greenfly, however, their predatory instincts reduce them to cannibalism until they have eaten enough to spin a cocoon from which the adult insect will emerge.  The entire life cycle takes only about 4 weeks, so that there will be several generations produced before the colder weather drives them in search of a warm winter home.

Common green lacewing (Chrysperia carnea) found in our moth trap

If you want to encourage lacewings to your garden – and with an appetite for aphids like theirs why wouldn’t you? – then you can make a ‘hotel’ for them.  The ‘hotel’ will be similar to the solitary bee hotels that all the garden centres and supermarkets sell nowadays full of short lengths of bamboo for the bees to nest in.  To make one, simply cut the top off a 2 litre plastic bottle (if nothing else it will stop the bottle from ending up in the ocean!), roll up a length of corrugated cardboard and put it inside the bottle so that the ends are protected from rain.  Then hang your hotel in the fork of a tree or under the eaves of your shed, pointing downwards so that water can drain out.  This may attract ladybirds as well as lacewings, a double blow to next year’s aphids.

Here are a few other species of lacewing proving that they are not all green or all that common.

A well marked species found on comfrey. Chrysopa perla

A brown lacewing or Alder Fly, possibly Sialis lutaria

Another species found in the moth trap, possibly Sympherobius elegans

November 2017

My apologies for rattling on about spiders again, but it does seem to have been a particularly good year for our eight-legged friends.  (Of course they are friends, they keep the fly population under control.)  We recently came home to find a garden spider (the one with the white cross on its back) apparently floating in mid-air.  It was, on closer inspection, in the centre of its web, but it was still way above the hedge and surrounding shrubs.  This spider, clearly dissatisfied with the diet obtainable by building a web between shrubs, had climbed the telegraph pole and suspended its web from the telephone wire.  This is as good a demonstration of spider planning and intelligence I’ve ever seen.

Garden Spider

I recently had a trip out to Aberdaron in North Wales where I was struck by the variety of wildflowers still in flower in mid-October.  The trees were starting to lose their leaves there but there was plenty of clover and knapweed in flower.  One particular species stood out - Common Fumitory.  There are only a handful of species of fumitory found in the UK and they are in a very small sub-family called fumariaceae.  I was quite surprised to find that fumariaceae is a sub-family of the poppy family, mainly because of the huge difference in the shape of the flowers.  Apparently they got the name fumitory from the smoke-like appearance of the plant with its grey-green leaves.  It is a certainly a very delicate plant with its fern-like leaves, though I would have called the leaves bright green.  An alternative name for the plant is earth smoke, though to appreciate the smokiness, perhaps you need to get up early when there is dew about and maybe squint a bit. The scientific name for common fumitory is fumaria officinalis.  Plants with officinalis in the name were normally used as herbs or medicines and fumitory is still used by herbalists to treat skin blemishes and conjunctivitis.  Interestingly common fumitory is a source of fumaric acid, which is something human skin produces when exposed to sunlight.  It is also a food additive, often shown in the ingredients list as an acidity regulator and has the E-number E297.  And if you have a taste for salt and vinegar crisps, then the vinegary flavour probably comes from fumaric acid.

Common Fumitory

One consequence of the late flowers is that the insects that depend on nectar are still about and we saw several red admiral butterflies.  This species used to be a migratory species.  Eggs were laid in Southern Europe or North Africa and several generations worked their way northward, arriving in the UK in late spring.  As the weather gets colder in autumn, they then fly south to over-winter and start the cycle again.  But now, with milder winters, there is less pressure to return south and so we now find that some red admirals hibernate here and together with the migrating population swell the total population in the UK.  A sister species of the red admiral is the painted lady which also migrates northwards from Africa and the mystery there was that nobody saw them flying back southwards.  It wasn’t until 2009 that investigations of insects using new radar techniques discovered that they do fly south but at altitudes of over 1000 metres (about 3,300 feet in old money).  The migration(at speeds of up to 30mph in favourable winds) involves a round trip of more than 9,000 miles and six generations of hungry caterpillars. 

Red Admiral

This is a much longer migration than the better known migration of monarch butterflies from Mexico to Canada.  So next time you see a red admiral or a painted lady you can marvel not just at their beauty, but also at just what a tough creature it really is.

Painted Lady

October 2017

Warning: This article makes reference to creatures with eight legs.  Well now that we’ve lost the arachnophobes we can talk about creatures that at this time of year suddenly seem to be everywhere.  They have, of course, been everywhere since the spring, it’s just that now they are much, much bigger, and consequently they build bigger and stronger webs to catch bigger meals for themselves.  And talking of size – now that the arachnophobes have gone – the average person is at least 150 times taller than the biggest UK spider, and at least 30,000 times heavier, so what’s the problem?  Having said that, however, I have seen some sizeable spiders recently.  On a recent survey at Rye Harbour I found a four-spot orb-weaver spider and two very impressive wasp spiders.

The four-spot orb-weaver was a large female with a brick-red abdomen that accentuated the four white spots on her back – a real beauty.  She had just caught a turnip sawfly and was injecting venom into it as I was taking photographs.  She had a very large abdomen that suggests that she was carrying a heavy load of eggs.  It has been found that a female with her egg load can weigh as much as 2.5 grams, and that after laying her eggs into the protective cocoon that will keep them safe until the spring, she only weighs 0.8 grams – less than half the weight of her eggs.  After the sawfly had been subdued, it would be eaten.  Unlike most other spider species that inject digestive fluids into their prey, and then suck out the resulting ‘soup’, the four-spot orb-weaver chews its prey and doesn’t leave the empty husk.  One bizarre fact I discovered while fact checking for this column was a quote from a research scientist who had done a spider taste test and found that… of the spiders tasted that day, ‘the four-spot orb-weaver – with a slightly nutty flavour – was the best’!

The turnip sawfly is part of the Hymenoptera family that includes bees, wasps and ants.  Like bees, the turnip sawfly adults feed on nectar and pollen, but unlike bees, wasps and ants, they don’t have a sting.  They get the name sawfly because the females have an ovipositor with a serrated edge that is used to cut into the plant stems in which they lay their eggs.  The turnip sawfly is bright orange with a few contrasting black bits – one of nature’s most reliable warning signs.  So if they don’t sting, why the bright colours?   It’s called a turnip sawfly because the larvae feed on brassicas – like turnips, cabbage, etc.  Brassica leaves contain substances called glucosinolates that give the leaves a bitter taste to discourage insects from eating them (and possibly to give children a reason to dislike sprouts).  But the sawfly larvae ingest the glucosinolates and concentrate it in their blood.  This can then be released in foul-tasting droplets to try and prevent predatory insects from eating them.  Even though the adult turnip sawfly doesn’t eat turnip leaves, its blood still contains the glucosinolates, hence the ‘don’t eat me I taste horrible’ colours.  Sadly for the turnip sawfly in the four-spot orb-weaver’s web, the spider ignored the warning.

September 2017

It is said that nature abhors a vacuum, and if proof were needed then our partly built pond would provide it.  Filled only with clean rainwater, it had many aquatic bugs in it even before we introduced a few plants into it.  One of the most notable visitors to the pond was a large emperor dragonfly which spent much time laying eggs into the pondweed.  This was several weeks ago, but already I have seen dragonfly larvae swimming about in there.  I have heard it said that dragonflies only live for a few weeks, but that refers only to the adults.  The larvae will lurk on the bottom of a pond for two or three years until the weather is fit for them to emerge as beautiful and aerobatic predators. The larvae are powerful predators that will eat anything from water fleas to small fish.  The adults are also agile predators that will take any flying insect, including smaller dragonflies.

Emporer Dragonfly (Female)

We caught sight of another aerial predator recently as a sparrowhawk flew over ignoring, and ignored by several seagulls as it flew past.  It was also ignored by a large gathering of house-martins and swallows that were flying round the house and landing on neighbouring roofs or telegraph wires.  Swallows and martins have nothing to fear from sparrowhawks which are neither fast enough nor agile enough to catch them.  Sparrowhawks method of catching prey is to use surprise, which they do by swooping low over hedges and fences, taking the prey while it is still perched in a bush or tree.  Swallows and martins are preyed on by a much more agile bird – the hobby, which will accompany swallows and martins as they migrate to Africa.  We assume that the gathering of martins and swallows was to do with migration which they won’t start until the flock is large enough.  A large flock of birds constantly shifting position within the flock confuses predators and just on numbers alone reduces the chance of an individual bird being taken.

Sparrowhawk (Male)

Birds of prey are almost defined by their prey and their hunting methods.  Sparrowhawks swoop, hobbies use sheer speed, and peregrines use that amazing vertical dive at nearly 200 miles an hour.  But there are many birds of prey that adopt more sedate methods.  Walk around Rye Harbour reserve and you are almost certain to see a kestrel hovering and keeping perfectly still waiting for a mouse or vole to stray into the open, the kestrel alerted to its presence by urine trails that reflect ultra-violet light.  The barn owl doesn’t quite hover, but moves very slowly above the ground, relying on silent flight and pale colours to hide it from its prey.

Larger raptors like marsh harriers or buzzards are able to take larger prey like rabbits or weasels which are generally slower moving and easier to see.  They use a swift pounce from slow soaring flight to secure their prey.  One of our largest raptors and one that you are increasingly likely to see in this area is the successfully reintroduced red kite.  How does that catch its prey?  Well, it doesn’t.  It is not a bird of prey, it is a scavenger that, when it is not being overfed by farmers in Wales that charge the public to see them, will take carrion or any other scraps it can find.  The red kite reintroduction has been so successful, that it makes you wonder why it became extinct in the first place.  Perhaps it was persecution by those same farmers who mistakenly saw it as a threat to their livestock.

August 2017

Midsummer can seem a quiet time in the natural world – the riot of spring flowers is over, those chicks that have survived the fledging process have moved on and the birds no longer need to sing to defend their territories or to attract a mate.  In the insect world as well, solitary bees have mated and laid eggs for the generation that will emerge next spring, bumblebee colonies have reached their natural end, and summer butterflies are now on the wing.  This natural progression through the year, though ultimately driven by the changing day length starts with plants, the base of the food chain.  In our lawn/meadow the clovers and vetches that started the floral year, are now dominated by the slower growing and taller plants like ragwort and wild carrot.

Wild Carrot Flower

Wild carrot (Daucus carota carota) is a sub-species with its cultivated sibling, the familiar orange-rooted culinary carrot (Daucus carota sativus).  It is an umbellifer, that is, it has a large flat-topped flower head that looks a bit like an umbrella.  It is one of the more elegant umbellifers and the buttressed flower heads always make me pause to admire nature’s beauty and complexity.  One thing that sets the wild carrot apart from most other umbellifers is that amongst the white florets, right in the middle of the flower head is a dark dot.  This dot is actually a couple of florets that are red rather than white.  Why should these florets be red?  I don’t know, but it is certainly not there so that we can distinguish wild carrot from other species.  One likely explanation involves looking at what pollinates the flowers.  Bees and bumblebees are rarely seen on wild carrot, they are much more likely to be pollinated by small flies or beetles, like the orange-red soldier beetles that frequently use the flat heads as a mating post.  So it may just be possible that evolution has favoured a flower head that contains a dark dot that from a distance looks like an insect already feeding there or perhaps an insect waiting for a mate?

A couple of other wild flowers that are in flower at the moment and can be seen around the village hedgerows are woundwort and black horehound.  Both are members of the large mint family, or lamiaceae, which are also known as labiates after their ‘lipped’ flowers.  The mint family also contains white dead-nettle that provides such good early forage for our bumblebees.  Woundwort has two species – hedge woundwort and marsh woundwort – the names of which clearly indicate where they are likely to be found.  Plants with the –wort suffix were used medicinally in the days before large drug companies decided what is good for us, and woundwort was used as its name suggests as a wound dressing.  Apparently marsh woundwort was the most effective dressing.  Woundwort is very similar to other plants with tall purple flower spikes, and I always check that it is woundwort by tearing off part of a leaf which has a distinctive and unpleasant, slightly antiseptic smell.

Black horehound is another plant with tall purple flower spikes and an unpleasant smell.  It has such an unpleasant smell that it has earned the alternative common name of Stinking Roger.   It is called black from its dark foliage and to distinguish it from the much rarer white horehound.  It is used as a nectar and pollen source for later emerging bumblebees and when we are doing bumblebee surveys, we always check black horehound for the rare ruderal bumblebee, and its rarer cousin the short-haired bumblebee.  Plants run a fine line between attracting insects to pollinate their flowers and deterring other insects from eating their leaves which is what the foul smell is all about.

Fleabane winning the competition for pollination

The bizarre spiky seed pods of wild carrot

And no need for lack of beauty while waiting for the seeds to ripen

July 2017

Apart from some exceptionally strong winds and a few thunderstorms, June has been its usual flaming self, though still unusually dry.  The birds have been getting on with bringing up the next generation.  A pair of swallows have been nesting in our carport again and as far as we can see are raising at least three chicks. Today I saw the swallows mobbing a magpie that was cowering on a neighbour’s roof.  I don’t know if the magpie had made an attempt to get at the chicks, or if the swallows were just making sure that it didn’t.  Either way, magpies are intelligent and ingenious birds and I wouldn’t be surprised if it found a way up to the nest even though it is tucked high up in a corner of the roof. 

Barn Swallow - Hirundo rustica

Talking of magpies, I read recently of an interesting experiment performed to see how nesting birds reacted to the presence of a stuffed cat compared with a stuffed squirrel and a stuffed rabbit.  This showed that the birds weren’t worried about the squirrel or rabbit but, as expected made a huge fuss about the cat.  One sad result from this research was that in a high percentage of cases where the cat was placed near nests, the nests were predated soon afterwards by magpies or jays that had been alerted to the presence of the nest by the birds attacking the cat.  We do seem to have a plague of hunting cats round us at the moment and though they may have little direct impact on birds by catching a few fledglings (especially when their thoughtful ‘owners’ fit them with bells), they have a much stronger indirect impact by revealing nests to other predators. 

We have had blue tits nesting in a box on the side of the house but we don’t know how many chicks there were as this box is not where we can observe it directly (and they won’t use the box with the camera in it!).  However, we have seen blue tit parents with young fledglings on our feeders, so hopefully we have given them a good start one way or another.   The sparrows have pushed the house martins out of their nests at the front of the house and seem to be raising chicks there.  (It is possible to discourage sparrows from stealing nests like this by hanging a curtain of short chains in front of the nest that the sparrows can’t negotiate, but that needs somebody happier on ladders than I am.)  The house martins have successfully occupied a nest at the back of the house and judging by the mess on the paving below, there is some breeding activity up there, but as yet we haven’t seen any heads poking out.

The only other nest of note is that of the buff-tailed bumblebees that have taken up residence somewhere under our shed.  (We have another in a pile of rubble in the 'untamed' part of the garden.)  We have a large shrub in the garden which is covered in white flowers (species unknown) and the bumblebees love it.  I have seen several fresh queen buff-tailed bumblebees feeding on the shrub and if they are from the nest under the shed then that marks the end of that colony – at least as far as the original queen is concerned.

Despite all these signs of new life, all is not well out there.  I heard recently that the worldwide biomass of insects has reduced by more than 80% in the last 100 years.  Chris Packham on Springwatch said that we have lost 44 million birds since 1970 – yes 1970! – including 51% of farmland birds.  What can we do about it? Grow flowers for pollinators, keep feeding the birds, chuck out the chemicals, and elect greener governments.  Some hope!

June 2017

We’ve had yet another unusual spring.  April and the early parts of May have been dry and sunny with no April showers or strong winds.  This has meant that the blossoms have been spectacular and long-lasting.  It seems that everything that can flower has flowered better than ever.  We’ve even had four bluebells come up in our lawn/meadow that we didn’t plant and have never seen since we moved here.  The bluebells in the field at the end of Peter James Lane have been wonderful as well.  One thing that you may not have noticed flowering are the oak trees.  Firstly, oak tree flowers are small, green and inconspicuous, and secondly they don’t flower every year – every 3 to 5 years is typical.  It has been found that oak trees in a forest all flower at the same time.  Beech trees do the same thing.  Apparently, the trees communicate using nerve impulses and chemical signals via their roots and the symbiotic fungi with which they swap nutrients.  The nerve impulses travel at one third of an inch per minute – slow, but maybe not so surprising in an organism that lives many hundreds of years.  This is all set out in a brilliant book called ‘The Hidden Life of Trees’ by Peter Wohlleben, a German forester.  And it’s not mumbo-jumbo pseudo-science either, everything is properly referenced to the appropriate scientific literature. 

There are good evolutionary reasons for this sporadic flowering of the trees (the years that they flower are called ‘mast years’ after the abundance of beech-mast) – firstly, flowering and producing fruit is expensive in energy terms and diverts resources from growing wood and leaves that would be used to harvest more energy from the sun.  Secondly, producing acorns or nuts every year would support a population of deer and pigs that would eat them all leaving none to grow into seedlings.  If all the trees in the forest produce acorns at the same time then there will be too many for the deer population to eat, especially a population that has been thinned by starvation or migration during the non-flowering years.  This is mitigated to some extent by the jays and squirrels that try to eke out the harvest by burying acorns or beech nuts, something that is helpful to the trees, whereas a reduced population of jays and squirrels is not so helpful.  Evolution, though efficient is often imperfect.   

This sporadic flowering of oak trees got me thinking about the knopper gall-wasps (Andricus quercuscalicis), whose bizarre life-cycle I wrote about in November 2014.  To recap briefly, the female gall-wasp lays eggs in the male flowers of the turkey oak; males and females hatch from the oaks, mate, and the females go and lay eggs in the female flowers of the English oak.  The generation that hatches from the English oaks are all parthenogenetic females that reproduce asexually and go on to lay eggs in the male flowers of the turkey oak and so on.  This made me wonder what happens to the gall wasps when there are no oaks in flower. (The gall wasps are not pollinators of oaks, or predators of species that do pollinate oaks because oaks are wind pollinated and don’t produce nectar to attract insects (hence the inconspicuous flowers).   I had assumed that the gall-wasps life-cycle was annual, but maybe that isn’t the case.    So how do the gall-wasps  survive when the oaks don’t flower – do they stay in their galls, if so, how do they know when to emerge?  Or can they survive using the isolated oaks that cannot communicate with their neighbours and flower out of synch?  Do turkey oaks communicate with English oaks?  Is the alternate sexual and parthenogenetic generation life-cycle of the gall-wasp an evolutionary response to the sporadic flowering of the oaks?   Nature is wonderful, but sometimes it just makes your head hurt.

May 2017

Last month I wrote about the small tortoiseshell butterfly which hibernates as an adult.  As spring moves on apace, one of the first butterflies that hibernate as a chrysalis has emerged - the orange-tip butterfly.  The males and females of the orange-tip are different (sexually dimorphic).  The male has the signature orange tips to its wings, whereas the female doesn’t and can easily be mistaken for a small white butterfly.  The female lays her eggs in the flower-heads of lady’s smock (cuckooflower), garlic mustard, or large bittercress amongst several other flower species.  There is a link here in the scientific names – the orange tip is Anthocharis cardamines, lady’s smock is Cardamine pratensis, and large bittercress is Cardamine amara.  It was only when researching this column that I found out that lady’s smock is related to hairy bittercress (Cardamine hirsuta), two very common and very different wild flowers.  The scientific name Cardamine incidentally, comes from its similarity to the cardamom plant, an entirely unrelated species. 

Male Orange-tip

One irritating feature of the orange-tip butterfly is that it rarely settles, at least in our garden, and at rest it is well camouflaged by tucking its forewings into its hindwings which it closes to show the green and white undersides.  This makes photographing them difficult, but last year I managed to photograph a female for the first time, and this year got a photo of the male to complete the set. 

Female Orange-tip

Apparently the caterpillars are well camouflaged as well, so I will be carefully examining our lady’s smock later on to see if I can find any.

Recently while working in the carport, I disturbed a moth.  At first glance it looked like a species I’d not seen before so I dropped my hammer and cable clips and ran for the camera.  Fortunately the moth was still dozy from the hibernation that I’d disturbed, so it was still there when I got back and it posed for several photographs.  Later, comparing the photographs with the moth book, it turned out to be a buttoned snout – a nationally scarce species.  It is called a buttoned snout from the resemblance of markings on its wing to a buttonhole.  It is mainly found in eastern parts of the country and there have been scattered records from along the south coast.  Perhaps the reason for this distribution is the food plant of its caterpillars which feed almost exclusively on hops.  We did have hops growing in the hedge last year so maybe that explains its choice of hibernation site.  This is not a species that turns up in moth traps, so I probably wouldn’t have seen one if I hadn’t been up in the carport sorting out the wiring.

Buttoned Snout - Hypena rostralis

While the spring is racing ahead, it does seem to be an unusually warm and early spring.  Our shed roof was in full flower in mid-April, something that doesn’t normally happen until early May.  (We have a Clematis montana that completely covers the shed roof.)  I also saw workers of both common carder and early bumblebees which shows that their colonies are already in full swing.  I read recently that eleven new species of dragonfly have bred in the UK since 1995, some completely new, some that have previously become extinct in the UK, but all expanding their range northwards from Europe.  All these facts suggest global warming, and all are facts to be ignored by the Trump’s and Cameron’s of this precious world.  

April 2017

Spring is a remarkable time of year.  As I write this there have been stunning displays of spring bulbs throughout the village and there are buds swelling everywhere.   On a day that was the second sunny day in a row, I saw my first small tortoiseshell butterfly of the year, three species of bumblebee, a large green caterpillar and heard two woodpeckers.  And just for a bit of extra excitement, a sparrowhawk swooped through the garden.  I saw, or heard all of this in just half an hour pottering round the garden, which just shows what a lively season spring is.

The small tortoiseshell butterfly hibernates as an adult which is why they can be seen flying so early in the spring.  When they emerge from hibernation, they will feed up on the nectar from willow catkins or dandelions, before mating and laying their eggs on young nettles.  Other butterflies that overwinter as adults are Red Admirals, Peacocks, and Brimstones, all of which will soon be on the wing as the weather warms and more nectar sources become available.

Small Tortoiseshell

I haven’t managed to identify the caterpillar, but I suspect that it is probably the larva of one of the Yellow Underwing moths, most of which overwinter as caterpillars.  They will then spin themselves a cocoon underground in which they will perform one of nature’s most amazing tricks as they rearrange their body plan from fat grub to elegant flying thing.  (Isn’t DNA brilliant!)

Unidentified caterpillar

Hearing two woodpeckers may, in fact, be an exaggeration.  I heard a woodpecker drumming, and I heard the yaffle of a green woodpecker.  More expert birders would have been able to tell from the frequency of the drumming whether it was a great-spotted woodpecker or a green woodpecker.  If it was a green woodpecker then I only heard one bird as the call and the drumming came at different times.

The three species of bumblebee are much more certain as I got a good look at all of them.  The first on parade was an Early bumblebee queen (Bombus pratorum).  This is one of our smallest bumblebees and is identified by having a red tail and yellow stripes, which distinguish her from the red-tailed bumblebee which, apart from the red tail, is all black.  This particular queen was searching round our flowerbeds and the various rodent holes on our lawn looking for a suitable nest site.  The buff-tailed bumblebee queen (Bombus terrestris) was also looking for a nest site, only this time in the crevices of a large pile of stones.  The buff-tailed bumblebee is our largest common bumblebee and if the winter is mild may be active for most of the year.  The common carder bumblebee queen (Bombus pascuorum) was not looking for nest sites, but feeding on the red dead-nettle that seems to be springing up all over the garden.  The carder bumblebees don’t nest underground or in crevices, but rather in hollows under tussocky grass where they scrape or ‘card’ plant material together on which to found their colony.

Early Bumblebee

I know that spring happens every year, but there’s something so magical about it, that it always seems to come as a surprise.

Buff-tailed Bumblebee

Common Carder Bumblebee

March 2017

There is a lot happening in space right now with probes looking at distant planets and asteroids, and many planned space missions that will launch soon to investigate gravitational waves, dark matter and all sorts of other phenomena.  One thing all of these spacecraft have in common is the need for power.  Most experiments are long-term and so battery power is not an option and neither is any sort of refuelling.  So they will get their power from the sun using solar panels.  The problem with that is that the panels need to be really big especially if they are going to be a long way from the sun.  In order to use large panels that need to be fitted inside much smaller launch modules, they will need to be folded.  Not only will they need to be folded, but they will need to unfold reliably because there will be no engineer there to give them a kick.  The designers, however, are looking much closer to home to see how best to fold them.  There are two things in nature that unfold reliably – leaves and beetles wings, and studying these has allowed the designers to improve the designs making them both lightweight and easy to deploy.

It may not be immediately apparent, but if you look at a freshly emerged beech leaf and at the size of the bud it has just emerged from, then there is a big mismatch.  The bud is much shorter and less wide than the leaf, and that is because the leaf is folded up inside the bud.  That initial burst from the bud is relatively rapid as sap is forced into the veins and the leaf flattens out, ready to quickly use the sun’s energy to provide the sugars and proteins the tree will need for growth.  The leaf will carry on growing until it reaches full size, but nowhere near as rapidly as that initial unfolding from the bud as can be seen in time-lapse videos of the process.  (There are plenty of examples on UTube.)

Even more remarkable than the unfolding leaf, is the beetle’s wing.  And it is remarkable because it has to fold as well as unfold.  Most flying insects have four wings – butterflies, bees, dragonflies to name a few, but beetles’ wings have evolved so that the forewings form a tough shell to protect them from predators, leaving the hindwings to do all the flying.  (Evolution didn’t quite get it right in this case though.  The whole point about flight is that it gets you away from predators, but if you’ve got a tough shell that predators can’t penetrate, then why have wings as well?  So, many beetles – appropriately called ground beetles – only have the tough outer shell that is firmly welded shut.)

Violaceous Ground Beetle - note the one piece wing case.

  If you look at a ladybird, for example, you may see its wing-cases open as it prepares to fly, but the unfolding of the hindwings is almost instant and too fast to follow.  You have a much better chance of seeing them fold the hindwings when they land and you will see the much longer hindwings tuck themselves under the wing-cases.

The remarkable thing about this wing folding is that there are no muscles in the wing itself.  The folding and unfolding is all done by subtle flexing of the wing at the joint where it is attached to the insect’s body, as well as having veins that curve and bend in such a way that they pop into a rigid structure when flight is required, and un-pop into folds when compactness is required.

Talking of veins, I didn’t realize until relatively recently that the veins in insect wings aren’t veins.  That is, they don’t carry blood around the wings.  When the adult insect first emerges from its cocoon, the wings are soft and it has to pump fluid into the veins to expand the wings to their full size. (Think butterfly and chrysalis.)  But once expanded, that’s it, the fluid doesn’t circulate. The veins are just there to stiffen the wings and if a piece of wing falls off or is knocked off by a predator, the veins don’t leak because there is no fluid after the initial inflation.  Amazing!

If you want to see leaves unfolding or ladybirds wings unfolding, then you don’t have long to wait, it’ll be happening in a garden near you any day now.

If you want to prove to yourself that a leaf can fit in a smaller bud, try this -

Take a piece of A4 paper and fold it lengthwise like so -

Then mark a line at about 60 degrees from about a third of the way along the fold, like so -

Then fold along the line you have drawn and fold back and forth in half-inch strips to make a shape something like this -

Then open out the paper like this -

Then the tricky bit is to reverse the folds on one half of the paper so that peaks become troughs and vice versa. (Use the edge of a ruler to fold it against.) It should then look like this. -

You can then cut it into a rough leaf shape if you want, like so -

Then you should be able to fold it enough to fit inside its bud, or at least so that it is both shorter and narrower than the original piece of paper - nature is much better at origami than us humans!

February 2017

Winter is a time to keep warm and contemplate. So I have been mostly contemplating feet. Nothing for chiropodists to worry about, I wouldn’t want to tread on any toes, so instead I’ve been thinking about birds’ feet.  Birds’ feet are particularly well adapted for what they do, which is to support the bird that they are attached to, in the way that the bird needs them to – which is to perch, hop, walk, run or cling.

Feet of a young robin - standard perching feet

The first thing to notice about a bird’s foot is that they are quite small – not because they don’t need to be bigger, but because they are lighter that way.  The whole of a bird’s anatomy is tuned to being as light as possible from beaks to hollow bones, not to mention the arrangement of the lungs and the amazingly strong and light feathers so that flight involves the least effort.  If you look at any flightless bird such as a kiwi, you will notice how stocky the legs are – the same basic pattern, but much heavier.

A pukeko, another flightless bird from New Zealand with
very sturdy legs.

A poor photo, but you can still see the 'tree-trunkiness' of the
 legs relative to the size of the kiwi.

  At the other end of the scale are swifts’ legs; these are short and almost useless because swifts spend the whole of their life apart from nesting, mating and fledging in the air.  If you see a swift-like bird perched on a wire then it will be a swallow or a martin, never a swift.

When it comes to perching, there are a number of ways this is done; most birds have three forward pointing toes and claws, and one pointing backwards.   This is an ideal arrangement for gripping a twig or a branch, but it’s not all about perching or roosting; woodpeckers and their ilk use the same arrangement to cling to the trunks of trees.  The three forward, one back arrangement works here quite well, but the relatively heavy woodpecker has also developed short and strong tail feathers which are used to brace it against the trunk. 

A young woodpecker, not a good photo but it shows long claws
 and the two very stiff tail feathers

Nuthatches and treecreepers don’t need to use their tail for balance; they rely instead on strong toes and longer claws than other birds.  The nuthatch is renowned for being able to climb down the trunk as well as up and it relies on an exceptionally strong rear claw to achieve this.  This gives them a different range of insects perhaps invisible to an upward facing bird like the treecreeper that doesn’t have that ability.  (I was once told that nuthatches have two backward facing toes but this appears not to be the case.) Whilst on the subject of perching – when did you last see a gull or a duck perched in a tree?  It is a rare sight, and you will only see them do it on relatively wide, flat branches and it is simply because they don’t have the rearward facing toe like other birds.  Their feet are webbed for swimming and the rear toe has been reduced to a small spur on the back of their legs. 

If you do happen to see a large gull sat in a tree, you may want to know if it is a greater or a lesser black-backed gull.  The most reliable indicator is not the greyness or blackness of their wings but rather that one has yellow legs, the other has pink legs.  All you need to do then is remember which is which!  Identification by birdwatchers is one thing that evolution hasn’t worked out yet, but feet can be quite distinctive.  Some birdwatchers reckon to be able to tell the difference between a willow warbler and a chiffchaff by the colour of their legs.  One has darker legs, but that really needs them sat side by side.  Apparently the only reliable indicator is that one has a notch in the third primary wing feather, the other doesn’t.  So you just need to catch it and then remember which is which! 

The Common Kestrel - in India

Same kestrel slightly enlarged showing the shiny black claws.

Recently I took a photo of a kestrel in a place where the lesser kestrel was also a possibility.  Fortunately, the difference is clear – the lesser kestrel has yellow legs and pale claws and the common kestrel has yellow legs and black claws – and beautifully shiny black claws they were too.