It’s a glorious sunny day in the third week of July and temperatures are tipped to rise above 25 degrees Celsius. Many species of flowering plants in the chalk grasslands in the North Downs close to London are in bloom. The conditions are ideal for watching butterflies. It's approximately the eighteenth month since Covid-19 arrived in the UK. We are into a second year where travel overseas is fraught due to the risk of sudden lockdowns and imposition of expensive hotel quarantine regimes. Once again it looks like a year where one’s precious annual leave will need to be largely or entirely used with domestic travel. Given that travel restriction within the UK have been lifted, it may seem unusual that a Londoner would want to use a day’s annual leave to travel to one of London’s suburbs. But I had found my weekends were not coinciding with ideal conditions for butterflies. On a Tuesday, with the weather forecast good, having taken a day’s leave I headed to Hutchinson’s Bank.
Hutchinson’s Bank is a block of land of just under 20 hectares managed by the London Wildlife Trust (LWT). The LWT’s primary interest in the site is because of the chalk grassland. But the site also has woodland bordering it which greatly increases the diversity of butterflies. The UK holds around half of Europe’s chalk grassland, with the North Downs having around five percent of it. Chalk grasslands are home to many special plants including an array of orchids as well as other chalk-loving plans such as Kidney Vetch and Greater Yellow Rattle. Both Kidney Vetch and Greater Yellow Rattle were much in abundance during my visit. The Greater Yellow Rattle is an interesting plant in the family Orobranchae (the Broomrapes and allies). Some of the genera in this family are total parasites. Their leaves are reduced and they do not photosynthesize. They live most of their life underground drawing their nutrients by being attached to a host plant. Only their flowers briefly emerge above the ground. Some of the genera in this family are partial parasites, appearing normal with photosynthetic leaves above the ground but with their roots attached to another host plant from which they draw nutrients.
Martin Wills is a local resident who has been studying the butterflies here for many years. According to him in just the last few years as many as 42 species of butterflies have been recorded at Hutchinson’s Bank. This is an impressive total when you consider the whole of the British Isles has 59 species which are recorded regularly. It is remarkable that this one site within Greater London has recorded just over two-thirds of the regular British list. Martin also reckons that in a typical year around 36 species can be seen, which is still over half the regular British list. My focus on this visit was the butterflies and I was not disappointed. One of the first butterflies I noticed when I arrived was a Glanville Fritillary, a Nymphalid butterfly with an overall orange appearance. The Glanville Fritillaries are confined to a few warm cliffs and undercliffs on the south coast of the Isle of Wight and the Chanell Islands. The ones at Hutchinson’s Bank are from a successful re-introduction effort and have become popular with photographers. The caterpillars need clumps of fresh Ribwort Plantains. Active management by the LWT by annually mowing the chalkland meadows ensures optimum conditions are maintained for the special chalkland plants as well as the invertebrates that depend on them.
Whilst I was there I heard the sound of excited children, and Laura Suckley, an LWT staff member arrived with a group of school children. I observed how children were taught how to use a butterfly net to carefully capture, examine and release butterflies. At the time of writing, the LWT is running a Brilliant Butterflies project. One of the project's aims is to encourage young people from the area to visit the site and connect them with nature on their doorstep.
Another of the butterflies that caught my attention was a Small Copper, one of Britain’s most attractive butterflies. Males have a habit of using a territorial perch. There were also many Meadow Browns and Gatekeepers, which are superficially similar, but with practice can be told apart. Also present and preferring to perch on the warm, grassy footpath which was mown short were Small Heaths. I spent a couple of hours without success trying to photograph the many Marbled Whites which were active. They are very distinctive in their black and white pattern, unlike the plainer Large and Small Whites which were also prospecting for nectar and mates. Also busy and rapidly patrolling the site was a single Clouded Yellow. I finally succeeded in photographing the Marbled Whites when a sudden thunderstorm blew in. As it arrived and the skies darkened and the atmosphere cooled, the butterflies settled down.
Hutchinson’s Bank is on a steep slope with woodland on top of the ridge and also lower down between the grassland slopes and Featherbed Lane. On these footpaths where shade and dappled light alternate, I have seen the Speckled Wood, a strongly territorial butterfly. I was walking along the bridlepath and paused to look at Marbled Whites when I found myself being buzzed by another butterfly that was using an overhanging perch as a vantage point to intercept intruding males. This was a Comma, which lays its eggs on Nettles. It’s a beautiful butterfly which nearly disappeared from Britain in the first half of the twentieth century only to make a remarkable comeback. When it closes its wings, it looks like a dead and decaying leaf which provides good camouflage for adults who spend the winter hibernating on the leaf litter-covered woodland floor.
Another dazzling and highly territorial butterfly was also present with a handsome red stripe on its wings. This was the Red Admiral which was present on the footpath which was bordered with emerging woodland. Interestingly, the Red Admirals seen in the early months are immigrants from Southern Europe. They lay their eggs and the adults die. The eggs hatch after a week and the caterpillars emerge and grow for around four weeks before forming their chrysalises from which later a new generation of adults will emerge. Thus the early Red Admirals may be European-born and the later ones born in the UK. Adults emerging in the cooler temperatures of September will make a return migration to Southern Europe to lay their eggs during the mild winter there. Prior to the return migration, in the UK they feed avidly on good sources of nectar including the introduced Buddelia and the juices of fallen fruits. Next spring, a new generation of adults will emerge in Southern Europe and travel to countries like the UK, starting the cycle anew.
The butterflies recorded by Martin Wills include a mouth-watering array of species, including stunningly beautiful butterflies such as the Purple Hairstreak. Jeremy Thomas writing about it in his ‘The Butterflies of Britain and Ireland’ says it is possible to walk under a tree bearing several hundred Purple Hairstreaks without being aware of their presence. He also notes that it probably occurs in every woodland containing a scattering of oaks in southern England and lowland Wales. But because the adults of many of the hairstreak species spend most of their life atop trees, they are seldom seen other than by keen butterfly watchers who know where to look. It is worth checking the websites of the local wildlife trusts and other local conservation bodies for guided walks for butterflies to have some of these hard-to-see butterflies pointed out to you. The book by Thomas and Lewington which is published by British Wildlife Publishing is one of the best butterfly books I have had the pleasure of owning. The writing by Jeremy Thomas is accessible, rich in detail and drawing on a wide range of scientific work and peppered with personal anecdotes from his own fieldwork. The illustrations are exquisite, by Richard Lewington, one of the best wildlife illustrators in the world. For help with the identification of species, one of the best books available is the Butterflies of Britain and Ireland: A Field and Site Guide published by A&C Black Publishers. With over 300 images showing the upperside, underside and sexes, together with text that has very useful identification pointers, this is my preferred choice for identification matters when I am studying my photographs on a laptop screen. But both of these books are heavy. There are several portable guides available. The Pocket Guide to the Butterflies of Great Britain and Ireland by Richard Lewington published by British Wildlife Publishing is one fine example. For a pocket guide with a wider geographical range, A Naturalist’s Guide to Butterflies of Britain and Northern Europe published by John Beaufoy is an excellent choice. I often have one or the other in my field bag when I am out photographing butterflies.
With my focus being on photographing butterflies, I would have seen fewer species than someone who was trying to see as many species as possible. Nevertheless I saw around a dozen species which is very good for a site so close to a huge city like London. With an increased awareness to provide the right kind of plants for both the larval and adult stages of pollinating insects, over time London can only become better for butterflies. Current initiatives such as the LWT’s Brilliant Butterflies project will help and more details are available online.
The 42 species recorded by Martin Wills at Hutchinson’s Bank are listed below.
- Skippers (Hesperiidae): Small Skipper, Essex Skipper, Large Skipper, Silver Spotted Skipper, Dingy Skipper, Grizzled Skipper.
- Whites and Yellows (Pieridae): Small White, Green-veined White, Large White, Orange tip, Brimstone, Clouded Yellow.
- Hairstreaks, coppers and blues (Lycaenidae): Adonis Blue, Chalkhill Blue, Small Blue, Common Blue, Holly Blue, Brown Argus, Small Copper, Green Hairstreak, Brown Hairstreak, White-Letter Hairstreak, Purple Hairstreak.
- Metalmarks (Riodonidae): Duke of Burgundy.
- Admirals, tortoiseshells, fritillaries and browns (Nymphalidae): Purple Emperor, White Admiral, Red Admiral, Comma, Peacock, Small Tortoiseshell, Large Tortoiseshell, Glanville Fritillary, Marsh Fritillary, Dark Green Fritillary, Silver Washed Fritillary. Speckled Wood, Wall Brown, Marbled White, Meadow Brown, Gatekeeper, Small Heath, Ringlet.
For people using public transport via Central London, the best option is to take one of the many trains to East Croydon and from just outside the station take a tram to New Addington. From there it is a two-minute walk to ‘Fishers Farm Household Reuse and Recyling Centre’ on North Downs Road. To its left is a footpath. Next, take a right fork which descends to Featherbed Lane and joins it at about 50 meters from Farleigh Dean Crescent (FDC) which is to the left. (The left fork is a ridge-top path, which is preferred by visitors who know their way around the place). Walk to the top of Farleigh Dean Crescent and continue along the surfaced footpath to the flower meadows and Hutchinson’s Bank which will have a signboard. It is better to take the top path at FDC rather than the lower one at the entrance to FDC which has a London Wildlife Trust information board. The site is open all day but there are no facilities.
If there are other butterfly watchers around ask them to show the way to Slimming’s Down, which is referred to as the Scrape. The short mown vegetation and the exposed chalk soil that has been created by scraping an area are good for species of Blues. Chapel Bank, another London Wildlife Trust reserve is around 10 minutes away from the scrape (Slimming’s Down) and is also superb for butterflies. It requires walking across an ancient chalk woodland (Threecorner Grove) and then crossing Featherbed Lane to the other side. The high street in New Addington (besides the tram stop) has fast food outlets and supermarkets. It is also possible to take buses from East Croydon and then take a long walk along Featherbed Lane. Use a mobile phone app like City Mapper for more information.
A number of groups in London organise a range of bird-watching and other nature walks as well as day trips by coach or by using public transport to sites further afield from London. Three groups which are especially suited for residents and visitors in Central London are the London Natural History Society, Marylebone Birdwatching Society and the RSPB Central London Local Group.
For visiting nature reserves in London, see also the websites of the London Wildlife Trust and London Wetland Centre. For nature-based activities for children and adults in a Central London Park, see the website of the Holland Park Ecology Centre.