Butterflies & Moths

Some kind of miracle

American Eastern Tiger Swallowtail butterfly (1). Image courtesy of www.publicdomainpictures.net.

Many of those who visited either of the presentations displaying the proposed new development on land at Highland Court Farm in Bekesbourne last week expressed suspicion at some of the claims made on the presentation boards. Not least of these is the notion, put forward by the developers, that their development will enhance biodiversity on the land. By this they mean: more individual species of flora and fauna would be present on the site in the years after the development.

There is a confused but partially valid argument here. While much of the land would of course be built over in the scheme, thereby destroying farmland and wildlife habitat, some of the proposed measures, like ponds, wild flower meadows and copses of trees, would undoubtedly attract a greater variety of species to those areas where they are located: but this should not be used to suggest that the proposed scheme is of benefit to wildlife overall.

However, to illustrate their point, the developers presented a board including what we might presume to be some of the wildlife we would hope to see in the revitalised areas of the farm. Among them were such valued native species as a reed bunting, a wild bee, a grass snake: all of which have been recorded in this area by BridgeNature.org in recent years. Yet remarkably, also included in the display, was what appeared to be an Eastern Tiger Swallowtail butterfly!

This is either an unfortunate error, or the developers are proposing some kind of ecological miracle, because the Eastern Tiger Swallowtail butterfly resides only in the Americas (2). Our own native species of Swallowtail, Papillon machaon britannicus, which looks rather different, lives only on the Norfolk Broads, primarily because its sole larval food plant, Milk-parsley, grows there. Occasionally, Britain is also visited by the Continental Swallowtail Papillon machaon gorganus which closely resembles its British cousin, not the American relative.

The proposal for development at Highland Court Farm may attract support or criticism, but we suspect there is very little chance that it will attract any Swallowtail butterflies on a permanent basis.

(1) The picture presented above is not the same photograph that was displayed in the presentation.
(2) In 1932, a single Eastern Tiger Swallowtail butterfly was discovered and captured in County Wicklow, Ireland, having been accidentally imported from America.

A pause, in the history of the Comma

Comma butterfly, The Butts, Bridge 2015. Image © Copyright BridgeNature.org 2017.

The photograph above shows one of our most beautiful butterflies, the Comma, pictured near the old railway at Bridge in 2015. Another has just been recorded near the same location in August 2017.

For hundreds of years at least, the Comma was one of the more common species of butterfly in Britain: its larvae fed on hop plants, and from the 15th to the 19th century, hops grown for brewing beer were a hugely significant crop in the British countryside. In those centuries, when sources of clean fresh drinking water were unreliable, beer, which is effectively water sterilised and flavoured by the brewing process, was the main source of daily fluid intake for the British population. In consequence the Comma butterfly would have had vast acreages of hop plantations on which to feed.

However, by the end of the 19th century, cheaply imported hops, increased taxation, changes in public tastes, and the indomitable popularity of tea (made with boiled water), meant that British hop growing went into massive decline: huge swathes of hop fields were pulled up, and the Comma butterfly, which relied on them, very nearly became extinct. It survived only in parts of Wales and in the remaining hop fields of Kent.

Yet astonishingly, just as the British people had changed their diet, the Comma seems to have gradually changed its diet too, and by adapting to eating nettles instead of hops it began to thrive again, right across the south of England. By the end of the 20th century the Comma had regained its place in the list of our most common butterflies: it was heralded by conservationists as one of the great comeback species of the natural world.

The 21st century has not been kind to British butterflies: huge areas of habitat have been lost and numbers have fallen. Yet once more the Comma appeared to defy decline, this time by increasing its geographical range across the country: it moved further north; the conservationists were thrilled. But in the annual national butterfly count of August 2016, run by the charity Butterfly Conservation, sightings of this beautiful butterfly suddenly fell by 46%*. Is this the beginning of the end, or just another pause in the history of the Comma? Only time will tell; so we too take a pause, as we wait for the results of this year’s count.

* In the same year a number of other butterfly species also saw huge declines.

*****UPDATE*****

14 OCTOBER 2017: We are pleased to announce that this year’s Big Butterfly Count revealed that the Comma butterfly has made a significant recovery. Numbers are up by an astonishing 90% and the Comma has recorded its second best Big Butterfly Count ever.

Butterflies at The Butts

Butterfly on The Butts, Bridge. July 2015

Butterfly on The Butts, Bridge. July 2015

The recent spell of hot weather has encouraged butterfly activity up on The Butts’ field across the old railway from Flint Cottages. This week a large number of butterflies, sometimes in dancing pairs, could be seen flitting across the wild flowers and grasses which grow there on the chalkland downs.

There are generally four species of butterfly to be seen and of course these include male and female which can be coloured differently, giving quite a vibrant spectacle for the observant viewer.

Marbled White butterfly. The Butts, Bridge.

Marbled White butterfly. The Butts, Bridge.

The Marbled White is the most obvious and easily recognisable butterfly in the field. It is a native of southern downland, like ours here in Bridge, with a preference for purple flowers such as thistles, knapweed and wild marjoram, all of which are growing in abundance in the area. Males and females have similar upper sides, but where male lower sides contrast light with dark, females contrast white and pale brown.

Meadow Brown Butterfly (Female). The Butts, Bridge.  Image copyright © Mike Burns-Stark 2015

Meadow Brown Butterfly (Female). The Butts, Bridge. Image copyright © Mike Burns-Stark 2015

The Meadow Brown is a grassland specialist and one of the most widespread butterflies to be seen in Britain, perhaps because it is willing to be active in dull weather when other species do not fly. The male is also one of our most drab butterflies in terms of colour, being an earthen brown, but the female is brighter with subtle hues of orange. Both have the ‘eye’ marking towards the end of the wing.

Small Skipper Butterfly. The Butts, Bridge.

Small Skipper Butterfly. The Butts, Bridge.

The Small Skipper is one of a number of Skippers that live in Britain. This is much smaller than the other butterflies seen at The Butts. Although one might assume its colour to be its most distinctive feature it is this butterfly’s flickering flight that tends to attract attention; most of the time it sits basking or resting unnoticed in vegetation. On close inspection we can see that at rest the fore wings lie at an oblique angle to the rear wing in a kind of half open position: this is distinctive of the Skippers.

Small Tortoiseshell butterfly. The Butts, Bridge.

Small Tortoiseshell butterfly. The Butts, Bridge.

The Small Tortoiseshell is one of the most familiar butterflies in Britain, commonly seen in gardens and farmland across the country. However this sense of ‘common’ is deceptive; alarm bells are beginning to ring for this once ubiquitous butterfly because its numbers are in rapid decline. Contrary to popular assumption the Small Tortoiseshell does not fair well in long periods of hot dry weather and as the summers of our latitude are becoming hotter and drier it appears that this butterfly may fall victim to global warming.

Also observed at The Butts this week was one blue butterfly which will be featured in another article to follow.

The Butterfly effect

Brown Argus Butterfly. Kingston

Brown Argus Butterfly. Kingston

The Guardian today reports that 2013, with its wonderfully warm summer, was an excellent year of recovery for farmland butterflies after their worst year on record in the wet weather of 2012. In that year, 52 out of the 56 species monitored saw their numbers decline. However, figures just collated and released by a coalition of conservation agencies indicate that numbers of the majority of the affected butterflies appear to have doubled in 2013.

Wet and windy summers, like that of 2012, have an adverse effect on the breeding cycle of butterflies, while hot summers, like the summer of 2013, are ideal for breeding, provided that there is no drought to kill their food sources. They are cold blooded and the shunshine warms them up, gives them energy and provides more sources of nectar for feeding.

In 2012 numbers of the Common Blue butterfly, which we often see on the Downs above Bridge plummeted by 60%, but in 2013 numbers increased five fold. Large White and Small White butterflies, often collectively called Cabbage Whites, increased by a factor of two and a factor of five respectively.

The most common butterflies, by abundance, are:
1. Small Tortoiseshell
2. Peacock
3. Small White
4. Large White
5. Common Blue

However, it’s not all good news on the butterfly front. Government figures show that overall butterfly numbers in the wider countryside have fallen by 49% since 1990 and reached their lowest point in 2012. This must surely be regarded as an ecological disaster! Butterflies perform an important role in the pollination of plants and are to some extent an indicator of the health of our countryside. At this rate of decline, things are not looking well.

The fearsome butterfly

The fearsome Peacock Butterfly. Image © Copyright BridgeNature.org 2015.

To us humans there is nothing much in nature that is less frightening than the harmless butterfly. With its delicate wings and pretty colours it has become a caricature of  gentleness and timidity as it flutters from flower to flower in search of nectar.

The butterfly has natural predators like birds, spiders, snakes and mice who will take advantage of this delicacy if they get a chance, particularly when it is at the stage of pupa, egg or caterpillar. However some butterflies do hibernate through the winter as a fully formed butterfly and need an extra level of self defence. One example is the Peacock Butterfly which is seen at this time of year in much of England.

With wings closed the Peacock resembles a dry dead leaf, but as a predator approaches and the wings are opened in alarm, what they see is a frightening creature like an attacking owl, with big angry staring eyes and a powerful beak that makes a hissing noise if they approach. Tests have shown that when confronted by potential predators the Peacock is so successful at frightening them away that it has a 100% survival rate in laboratory studies, which is far higher than most other butterflies have achieved.

The Gatekeeper

Gatekeeper Butterfly (Male). Kingston. Aug 2013. Image © Copyright BridgeNature.org 2015.

The attractive ‘Gatekeeper’ butterfly is so called because it was often seen around the taller grasses and brambles growing at farm gateposts and toll gates where, in days of old, there would have been men employed as gatekeepers. It remains a common sight in southern England with peak numbers appearing in early August.

Another name for this butterfly is the Hedge Brown, which only adds to the confusion when comparing it to the very similar Meadow Brown which is often seen in the same areas. However, although the two appear similar in flight and with their wings closed, only the Gatekeeper (Hedge Brown) has the double pupils in the eyespots on the forewings. The bars or dark ‘brands’ half way up the forewings indicate that the picture (above) is of a male.

 

Elephant Hawk-moth

Elephant Hawk-moth, Ford Close, Bridge

Our thanks to Brigid who contacted BridgeNature.org regarding a beautiful moth seen in her garden early one morning this week in Bridge. We managed to get a picture of it as the sun came up over the trees.

The moth is an Elephant Hawk-moth. They are relatively common and can be seen occasionally in gardens, woodlands and grassland at about dusk between May and July.

Elephant Hawk-moth caterpillars can be seen from July to September and are quite spectacular in green or brown. Near the head they have two large, black eyespots which they can expand to frighten predators. They will over-winter as chrysalides before the metamorphosis.