Tuesday, 26 March 2013

Time for action ...

2012 was the worst year on record for UK butterflies.

We all knew it, but it's now official ...

"Washout 2012 was the worst year for UK butterflies on record with 52 out of the 56 species monitored suffering declines, a scientific study today revealed. Some of our rarest species, such as the fritillaries, bore the brunt of the second wettest year on record and now face the real threat of extinction in some parts of the UK.

Last year’s relentless rain and cold created disastrous conditions for summer species in particular as they struggled to find food, shelter and mating opportunities; butterfly abundance plummeted to a record low as a result and 13 species suffered their worst year on record. The critically endangered High Brown Fritillary fell by 46%, the vulnerable Marsh Fritillary was down 71% and the endangered Heath Fritillary saw its population plummet by 50% in comparison to 2011. Many of our most threatened butterflies were already in a state of long-term decline prior to the 2012 deluge. There are now real fears that these already struggling species could become extinct in some parts of the UK as a result of last year’s wet weather.

Hairstreaks did particularly badly last year - the Black Hairstreak, one of the UK’s rarest species, saw its population fall by 98%. The Green Hairstreak was down 68%, the White-letter Hairstreak fell by 72% and the Brown Hairstreak, slipped by 34%. Many common species also struggled. The Common Blue plummeted by 60%, the Brown Argus collapsed by 73% and the Large Skipper fell by 55%. The widespread ‘Whites’, including Green-veined White, Large White and Small White, saw their populations tumble by more than 50%. The Orange-tip fell by 34%. The alarming slide of garden favourite the Small Tortoiseshell continued, with its population slipping 37% from 2011 figures. Only four species saw their populations increase. The grass-feeding Meadow Brown was up 21% and the Scotch Argus, which thrives in damp conditions, rose by 55%.

Dr Tom Brereton, Head of Monitoring at Butterfly Conservation, said: "2012 was a catastrophic year for almost all of out butterflies, halting progress made through our conservation efforts in recent years. Butterflies have proved before that given favourable conditions and the availability of suitable habitat they can recover, but with numbers in almost three-quarters of UK species at a historically low ebb, any tangible recovery will be more difficult than ever.

Data was gathered by the UK Butterfly Monitoring Scheme (UKBMS) jointly led by Butterfly Conservation and the Centre for Ecology & Hydrology (CEH).

UKBMS has run since 1976 and involves thousands of volunteers collecting data every week throughout the summer from more than 1,000 sites across the UK. CEH butterfly ecologist Dr Marc Botham said: “Despite the horrific weather in 2012 over 1,500 dedicated volunteers still managed to collect data from over a thousand sites across the UK. Their amazing efforts enable us to assess the impacts of wet summers on butterfly diversity.”
The UKBMS is operated by the Centre for Ecology & Hydrology and Butterfly Conservation and funded by a multi-agency consortium including the Countryside Council for Wales, Defra, the Joint Nature Conservation Committee, Forestry Commission, Natural England, the Natural Environment Research Council and Scottish Natural Heritage. The UKBMS is indebted to all volunteers who contribute data to the scheme."

Dr Tom Brereton
Head of Monitoring at Butterfly Conservation

But it’s not too late if we act now …

In Sussex, last ‘summer’ checked the upward population trend for the rare Duke of Burgundy. Nevertheless, our conservation efforts over the previous years means that 2012 will have seen a decrease, not an extinction, of this rare and beautiful butterfly. This tells me that we must highly value and protect what we have. It tells me we must continue to research and keep learning - we may only have 59 native species of butterfly in the UK but there is still much we do not know. We must learn from our successes and we must learn from our mistakes. We must educate and we must conserve. We have no control over the weather but we do over our attitudes and actions – we have the ability to change things.

If you have the time and the ability to get involved with a local conservation project, run by your local branch of Butterfly Conservation, then please consider getting involved. You won’t regret it, and I can guarantee you will get far more out of it than you put in.

We have a responsibility …

Thursday, 14 March 2013

Research ...

Hope Department of Entomology, Oxford

Over the past couple of months, I have been fortunate to spend some considerable time in the good company of Pete Eeles at the Hope Department of Entomology at Oxford’s University Museum of Natural History (OUMNH). Pete, who runs the UK Butterflies website at www.ukbutterflies.co.uk, has added, and continues to add, considerable value to this excellent resource and it has been my pleasure to join him on what can only be described as a mutually rewarding adventure of discovery.

As an example of our earlier and continuing research the Large Blue (Phengaris (Maculinea) arion) has played a significant role. Our studies have involved tracking down specimens from lost colonies and reviewing historic literature relating to their final outposts e.g. from areas including North Cornwall, South Devon, Somerset, the Cotswolds and Barnwell Wold in Northamptonshire. The image capture process, expertly undertaken by Katherine Child (OUMNH), has provided an excellent means of better understanding the original descriptions and has provided an excellent graphical means of comparing regional colonies. Some of the specimens we have selected for inclusion are historic in their own right, in that they have been used in past reference works, not least, the Barnwell Wold specimens of P. arion from the important Dale collection, which feature on Plate 12, Figures 1 and 2, in Butterflies by E. B. Ford (pictured below).

Of the literature, which has been reviewed, the diaries and correspondences of the late James Charles Dale (1792-1872) have transported us to a period when Large Coppers, Mazarine Blues, Swallowtails, Bath Whites and other lepidopteran wonders graced our countryside. The middle image below, showing Dale's log from circa 1835, is of particular interest as it details the capture of Papilio arion, now Phengaris arion, from Mouse's Pasture, Bromham near Bedford. Examination of other diaries in Dale's archive also indicate reference to this location which is referred to in A History of British Butterflies by the Rev. F. O. Morris, 1853. Dale’s diaries and communications have sometimes been a challenge to read, but the effort has been worth it, as their contents continue to take flight into our imagination.

The search continues ...

Friday, 8 March 2013

Frogsporn ...

West Sussex, 8 March 2013

Overnight, and exactly a year to the day, my pond is once again awash with frogspawn.

I woke this morning to a mass of frantic sexual activity, with at least seven individuals taking part in this annual mating pilgrimage. Every year I keep watch for returning Common Frogs (Rana temporaria), their presence generally betrayed by their calling.

With heavy rain falling for most of today, I decided to keep my camera dry. The picture below was taken on 11 March 2012.

A positive sign of spring ...

Thursday, 7 March 2013

Morphology ...


Most identification of Lepidoptera does not require the use of a dichotomous key (a means for the identification of organisms based on a series of choices between alternative characters), but relies on pattern recognition and learning the species verbatim from images in books and the internet, the ability growing with experience. However, in most other large orders (e.g. Diptera, Coleoptera and Hymenoptera) even the beginner must learn from keys, or diagnostic characters to be able to distinguish taxa even at the family level. Although there are exceptions, it is generally not until the lepidopterist begins to tackle the microlepidoptera that the use of morphological characters (e.g. genitalia, wing venation and body structure) becomes commonplace, and often a prerequisite, in aiding identification.

Most butterflies and moths have two pairs of overlapping scaled wings. These are comprised of an extremely thin double membrane with rigidity provided by a network of nervures (the hollow ‘veins’ which radiate from the base of and form the framework of the insect’s wing). The pattern of nervures is different for each genus of butterfly and, as such, this is one of the key criteria used by taxonomists when classifying butterflies.

To venture a little deeper, the fore and hindwings of most moths, though not all, are united during flight by a coupling apparatus, the frenulum (a bristly structure on the hindwings that holds the forewings and hindwings together). This particular mechanism is never found in butterflies, in which the wings are held together only because the front pair overlaps the hind to a considerable extent. The amount of this overlap is increased by the humeral lobe, a special projection found only in butterflies, and situated at the basal end of the costa on the hindwings. This type of arrangement is known as amplexiform (clasp-like) wing-coupling.

The image below, of a female Brown Hairstreak (Thecla betulae), shows the humeral area, close to the rear and either side of the thorax. In addition, key wing venation is visible, including the radial and medial veins on the hindwing, and the radial, cubital and anal veins located on the forewing. The discoidal cell of the forewing is also clearly discernable.

A  Humeral area
B  Radial nervure (vein)
C  One of the medial nervules
D  Radial nervure (vein)
E  One of the cubital nervules
F  Cubital nervure (vein)
G  One of the anal nervures (veins)
H  Discoidal cell

I appreciate that this level of detail, which by no means is digging very deep, is not to everyone’s interest. However, for those who have the time and the inclination to do so, I thoroughly recommend looking a little closer and you will soon discover a whole new world full of fabulous hidden wonders …

Try it sometime ...