Thursday, September 27, 2007

European mole Talpa europeae

I am an amateur naturalist trying to identify everything living in my garden.

Typical isn't it, you wait thirty-seven blog postings for a garden mammal, and then two come along at once. After my triumph of badger photography, ladies and gentlemen I present photo 1: the European mole (Talpa europeae). As may be obvious from the photo, though mole hills have periodically appeared in my garden for a number of years, I (in common with most people) have never actually seen a live example of this elusive little creature that lives almost its entire life underground hunting for worms and insects.

To learn something about moles I have been reading The Mole (Kenneth Mellane, Collins New Naturalist). Having been written over thirty years ago (1971) I expected the information in the book to have dated somewhat, and indeed the extensive treatment of the methods employed by mole exterminators and the suggested method of tracking moles by fitting rings of radioactive Cobalt-60 (!) to their tails might less readily find their way into a textbook aimed at amateur naturalists today. Interestingly however, though my searches have been far from exhaustive, turning to the internet I've yet to come across any very detailed site describing the ecology of this most secretive of British mammals (can anyone point me to one?).

From Dr Mellane's book I learn that the average male mole comes in at 14.3cm, 110g with females marginally smaller. European moles are not entirely blind, though their eyes are tiny and mostly hidden by their fur (which, I learn, has no particular 'lie' i.e. it responds equally to being stroked in either direction, unlike the fur of, say, cats as pet owners will know). Moles have a highly developed sense of touch - their snout being covered with thousands of tiny, sensitive 'pimples' known as Eimer's organs. I have to confess at first reading I was highly sceptical of the suggestion in the book that:

"it is tempting to think that moles have other and more unusual senses...[finding] its way in its burrows by some sort of "radar" using some radiation we do not experience"

Subsequently however I've come across the NSF Digimorph site, where I read:

"some authors have suggested that the nose of Talpa may be sensitive to electrical or magnetic signals"

Can anyone comment more concretely on whether moles do or don't have senses of this nature?

Apart from a short time spent mating, moles are, as Dr Mellane puts it:

"aggressive, quarrelsome and solitary"

The Arkive site explains that female moles are the only mammals to contain vestigial testes ('Ovotestes'). These produce large amounts of testosterone and it seems this may account for the tendency of female moles to be just as aggressively territorial as males.

Gestation in moles lasts four weeks. Birth is in late April in the South of England, and the young start to leave the nest (one of the few times they may travel above ground) after about a month to establish territories of their own.

Of course, the most widely recognised feature of moles is their hills. They've certainly made quite a mess of my normally immaculate (hem, hem) lawn as photo 2 shows (does anyone know of a humane way of getting rid of moles incidentally?). Moles are extremely skillful tunnelers: burrows may be on multiple levels and in experiments in which whole sections of burrows where removed, Dr Mellane found that they will even pack together balls of clay to reconstruct a tunnel arch. Moles work and sleep in 3 hour shifts (3 awake, 3 asleep etc.) and Dr Mellane likens the effort a mole makes in pushing up the soil in a molehill to a human miner moving 12 tons of soil in an hour.

Occasionally moles may construct giant mole-hills known as 'fortresses' comprising hundreds of kilos of soil. The suggestion seems to be that fortresses are built to raise a brood chamber above the water-level in flood-prone areas. Dr Mellane disputes this however, and asserts that their real purpose remains a mystery.

Finally, I warned last time of the perils of listening to badgers! The lesson from King William III of England's death is that moles can be just as bad for your health. In 1702, William was thrown from his horse when it tripped over a mole hill. William broke his collarbone and subsequently died from complications. I shall be watching where I tread when I next time mow the lawn!

Thursday, September 20, 2007

The European Badger Meles meles

I am an amateur naturalist trying to identify everything that lives in my garden.

Photograph 1 may not be about to win too many wildlife photography competitions (!) - but after more than thirty postings describing the creatures that visit my garden, I am pleased to announce my first mammal: the European Badger (Meles meles).

I must confess that strictly I have not actually seen said badger(s) in my garden, but on the basis that: i) I do not know what else, besides a badger digging for worms, could have left the holes in my lawn in shown in photos 1 and 2 ii) it's not uncommon to see dead badgers on the roads within a mile of my house iii) lying in bed at night I'm fairly certain I've heard the 'wailing' of badgers (very helpfully, the good people of the Department of Zoology at Oxford University have placed a detailed series of badger-call audio files on their site) and iv) my neighbour has seen badgers in his garden - I'm reasonably confident to assert their presence.

Being one of the UK's few, large, wild mammals so much has been written about badgers (not least with regard to the UK government's controversial policy of culling them on the basis of their supposed ( but strongly-contested) link to the spread of tuberculosis in cattle) that it seems almost pointless for me to add more. Since my own purpose in penning my blog is to fix in my own mind some knowledge of my garden's natural history however, I'll press on:

To learn something about badgers I have been reading The Badger (E. Neal, The New Naturalist Monographs, Collins, 3rd ed.). With the greatest respect to the author, having been written in the 1940's, I did find some of the anecdotes just a little dated, but nevertheless came away with a much improved knowledge of this most secretive of mammals.

The European badger is spread across Europe and Asia from Britain to Japan. It is part of the Mustelidae family of mammals which includes weasels, otters and wolverines (none of the latter in the UK). An old, common name for the badger is Brock and in the UK it's not uncommon to find towns and villages with names like Brockhampton and Brockenhurst.

Badgers have the dentition of carnivores - large canines and extremely powerful articulated jaws - but their diet is basically omnivorous. In his book Dr Neal describes his studies into the stomach contents of badgers and reports finding, amongst other things: rabbit bones and fur; grass; beech nuts; shoots of Dog's Mercury (Mercurialis perennis); 45 beetles of the genus Geotrupes; large numbers of earthworms; four hedgehogs (but only 3 spines swallowed); and a stomach full of wasp larvae and comb.

Badgers are communal, and live in underground dens called sets. Set tunnels can extend for more than a hundred metres into hillsides. In Dr Neal's book he describes his studies of the badger population in a 45-acre wood: Conigre Wood near Rendcomb (UK). Despite the many changes to the British countryside since the 1940's I was delighted to find the 2007 picture of Conigre Wood on Google Earth is essentially identical to the black and white photo in Dr Neal's book (Conigre Wood is the large slanted " j" - minus the top dot - in the centre of photo 3) (as here, I understand it's o.k. for me to use Google Earth images). In the book Dr Neal reports there being five badger sets in the wood of which two were large and regularly used. In all, the woodland supported 11 badgers in 1945. I wonder how many are there today?

One of the more remarkable facts I discovered from reading Dr Neal's books is that for badgers there is a very considerable delay between conception (i.e. the act of mating and a female badger egg becoming fertilized) and "pregnancy-proper" (my phrase) when the fertilized egg becomes implanted in the uterine wall. For three months or more following fertilization, the egg simply 'floats around' inside the female as a so-called blastocyst. Only once the blastocyst becomes implanted in the uterine wall does the embryo start "serious" development, with birth occurring 7-8weeks later. The result of this delay is that although a male and female may mate in Spring, birth does not normally occur until December or January. Badger cubs are weaned after 12weeks and will normally leave the parental set within a year.

Finally, for those of you tempted to listen out for the calls of badgers, you may want to take steps to ensure there are no owls in your neighbourhood! According to a manuscript from 1800 quoted in Dr. Neal's book:

Should one hear a badger call
And then an ullot [owl] cry,
Make thy peace with God, good soul,
For shortly thu shalt die.

Ear-plugs in bed from now on ?!

Saturday, September 15, 2007

An Ichneumonoid Wasp Netelia testacea

I am an amateur naturalist trying to identify everything living in my garden.

Photo 1: "I vant to drink your blood!"

Actually, that's not true at all! If you're unfortunate enough to be a caterpillar however, he (/she?) wants to do something even worse to you! Read on:

On the same evening as I met the Brimstone moth in my previous posting, the red wasp in the photo was also fluttering around my night light. Photo 2 (click on photo's to enlarge) shows my wasp's beautifully slender waist and photo 3 (shot from below) his/her long antennnae.

Using the colour plates in Michael Chinery's excellent "Field Guide to Insects of Britain and Northern Europe" (Collins, 3rd Ed.) I've been able to identify my wasp as a member of the Ichneumonidae family of wasps. The Ichneumonidae are parasitic wasps in the grizzly business of laying their eggs on, or inside, caterpillars. In the latter case, when the eggs hatch the unfortunate caterpillar, often still alive, is eaten from the inside out. For those with strong stomachs, this site has lots of quality images of unfortunate caterpillars being variously parasitised.

As I repeatedly discover for the creatures on this site, it seems that a certain Charles Darwin has beaten me to comment. He was so struck by the grizzly business above that in an obscure little book (!) entitled 'On the Origin of Species' (you can find the complete, searchable text on the excellent Darwin online site incidentally) he wrote:

"to my imagination it is far more satisfactory to look at ...the larvae of ichneumonidae feeding within the live bodies of caterpillars,- not as specifically endowed or created, but as small consequences of one general law...namely, multiply, vary, let the strongest live and the weakest die."

If he keeps up his hobby, who knows, one day his natural-history writings may be as famous as mine (hem, hem!).

As every amateur naturalist knows, a bewildering array of insects can be found in the average garden. The question arises therefore, how do you know when you've found a Ichneumon wasp? Common features are long antennae and the long slender ovipositor, as with hoverflies however, ultimately identification rests on an analysis of the venation of the wings. Photo 4 (you'll need to click to enlarge) highlights the wing vein that, as I learn from Micheal Chinery's book above, indicates my wasp is indeed a member of the family Ichneumonidae.

Incidentally, I in no way harmed the wasp in photo's 2 and 3. He/she was released back into my garden after I'd taken my snaps. I can only ask that you take me on trust when I explain that by complete coincidence, 24 hours later, I found a superficially identical dead wasp on the upstairs carpet in my house. It was he/she who contributed the wing to photo 4.

When it comes to an identification of a particular species of Ichneumon wasp, as with beetles, things are much more tricky. There are some 3200 British and Irish species species (and more than 12000 worldwide). Gavin Broad has added an online checklist to the Biological Records Centre database. Based on the colour plate in the book above and its description as:

"one of our commonest ichneumons...Adults often come to lighted windows"

I'm going with the identity of my wasp being Netelia testacea. Unfortunately, as the book adds however:

"Ophion species are superficially very similar, but their venation is slightly different"

and indeed, googling Ophion yields pictures of wasps very similar to mine. Sadly the book gives no further details on separating Netalia from Ophion species. Gavin Broads has helpfully added a pdf key to Ichneumons to the BRC database, but, as he admits in the introduction,

"Identifying ichneumonids can be a daunting process...".

As an amateur I feel I'm lacking in the time (and very likely the skill) needed to work through the several dozen pages of microscopal details in the key. If anyone can confirm or deny my guess at Netalia testacea based on the face- and wing-images above therefore I'd be grateful.

Finally, a word on antennae! Insect antennae fascinate me. Using these tiny flexible rods, I read accounts of insects' ability to detect mating partners and food, sometimes from miles away. For no more reason than simple fascination value therefore, photo 5: a closeup (x100) of the tip of my wasp's antenna. Another of mother nature's tiny miracles.

Saturday, September 8, 2007

Brimstone moth Opisthograptis luteolata

I am an amateur naturalist trying to discover what lives in garden.

As part of my mission to blog all my garden's life , I have so far covered a number of insects. So far however, all have been found during the hours of daylight. The rules of my mission are that I should identify all lifeforms however, so recently I left an outside light on after dusk and was delighted to come back an hour later to find the moth seen in photo one (click to enlarge).

From the characteristic lemon-yellow colouring and patches of brown on the costa (the leading edges of the wing), and using my copy of 'Butterflies and Moths of Britain and Europe' (Collins), I'm confident in my identifying my moth as the Brimstone Moth.

My moth's Latin name is Opisothograptis luteolata, which, by piecing together snippets of information from various sources, I believe translates as Opistho =backwards , graptis=graphics/writing , luteolata= yellowish : "the yellow-with-backward-facing-graphical-symbols moth" though I'm happy to be corrected.

In an effort to learn more about moths I have been reading the excellent and scholarly 'Moths' (Michael Majerus, The New Naturalist series). There are so many fascinating facts contained in this book that I'm sure I'll be referencing it many times in the future. Specifically on the subject of the Brimstone it mentions that it, together with a two other British moths (the Scalloped Hazel and the Peppered) was the subject of an extensive study in the 1890's showing that the caterpillars of these moths vary in colour according to the colour of the plant on which they feed, so as to afford the best camouflage protection. This site has pictures of the brown and green form of Brimstone larvae. Amongst various other shrubs, Brimstone caterpillars feed on apple, birch, rowan and hawthorn.

Those who read my blog will know I don't like to cause harm to any of the creatures in my postings. Sadly however, rather than finding my moth fluttering around my outside light, when I found it it was lying dead on the ground. I suppose it could be that the wall light itself somehow caused my moth's death (by e.g. causing my moth to collide with the wall). Equally, perhaps my moth was simply at the end of its lifespan - an old moth that used the last of its energies in a flight "towards the light!". I have read that some adult moths are doomed to a pitifully short lifespan by a lack mouth parts with which to feed (the purpose of the adult being simply to mate, lay eggs and die, feeding being unnecessary). This led me into a minor quest to try to ascertain whether adult Brimstone moths can feed and if so, on what. My moth was equipped with a proboscis and from Ian Kimbers moth site I learn that adult Brimstones can produce a number of broods across the season from early May to mid-August. Both thse facts suggest an extended lifespan. With the exception of a few vague reference to adult Brimstone moths feeding 'on plants' however, I've been unable to find any detailed description of what they eat. Can anyone comment?

Brimstone moths overwinter as pupae. Naively perhaps, of the options open to a moth - egg, larva, pupa and adult ('imago') - the rather 'dormant' pupal state seemed a natural overwintering choice to me. The Brismtone is a member of the Geometridae family of moths however, and from Michael Majerus' book I was fascinated to learn that of 288 British species of Geometridae, although 152 do indeed opt to overwinter as pupae, 41 do so as eggs, 88 as larva, and surprisingly (to me anyhow) 7 as adults. I imagine that uncovering the ecological factors that influence these choices presents a wealth of opportunities for scientific study.
And finally, partly in response to a recent comment received on this blog, and partly since I simply enjoy them: some microscope picture (click to enlarge) of the wingscales of my moth (400x magnification).