Naturalists at Hutchinson’s Bank nature reserve are celebrating the sighting of a rare butterfly.
Naturalist Martin Wells captured this image of the rare brown hairstreak butterfly at Hutchinson’s Bank
Hutchinson’s Bank is one of the richest remaining chalk grassland habitats in London, and this year it has been just a touch richer with the appearance of the brown hairstreak butterfly.
London Wildlife Trust has been working to expand habitats for around 30 butterfly species at the nature reserve. The butterflies include grizzled skipper, dark green fritillary, small blue, brown argus and chalk hill blue. All have been helped to thrive by the Trust’s work to reduce scrub encroachment and allow controlled grazing, but it was the sighting of the brown hairstreak that really highlighted the project’s success.
These rare butterflies spend their time high in the tops of ash trees, where they feed on honeydew from aphids and bask in the sun, or hiding among thick hedges. This summer Martin Wills, a local volunteer, was lucky enough to spot a brown hairstreak at the reserve in New Addington.
Shaun Marriott, a reserve manager for London Wildlife Trust, said: “It is very encouraging to see the brown hairstreak back at Hutchinson’s. They are very elusive and haven’t been seen here for many years.
“We have cut back the scrub to make way for wildflowers, but it was important we didn’t remove too much because the brown hairstreak lays its eggs on blackthorn. Seeing the butterfly here means we have managed to strike a balance and get the best of both worlds.”
Many butterfly species, including the brown hairstreak, have experienced severe declines in numbers over recent years and work to improve and expand their habitats is crucial to reversing this trend. Nationally, areas of chalk grassland like Hutchinson’s Bank have reduced by 97 per cent in the last 60 years because of suburban development, invasive species and changing farming methods.
Climate change could also add another threat to this habitat in future. With only around 40,000 hectares remaining, chalk grassland is now a priority habitat under the UK Biodiversity Action Plan (BAP).
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Excellent news , about the appearance of this rare butterfly, against the sad general background of declining butterfly, moth and wild bee numbers over last 30 years. The presence of this species is a great reward for the wise habitat management of the site by the London Wildlife Trust, who clearly recognise the benefit of keeping a good proportion of scrub when opening up and restoring the wildflower -rich chalk grassland habitat.
A note of worry…….. I was interested to read in the article that the butterflies like spending time time in the tops of ash trees. Let us hope that the tree disease “Ash dieback” (Chalara dieback of ash) – does not get a deep hold in the UK. It is killing ash trees here, and has decimated ash populations in France and other countries. (for details see tree pests and diseases – Forestry Commission
https://www.forestry.gov.uk/ashdieback
by Forestry Commission – 2003
for ” Details of the threat to UK ash trees from ash dieback caused by the Hymenoscyphus fraxineus fungus, formerly known as Chalara fraxinea”.
With regard to the overall decline in butterflies, my guess is that , in the countryside, the fields are all too neat, without the native flowering plants (aka “weeds”), so that there is not enough food for insects over the year. Some areas now are all wheat, all barley, or all rapeseed, creating monocultures with flowers at only a few times, not all year. This mirrors the decline in the number of family-owned small and medium sized farms, with their varied land management practices and crops, which gave a chequer board variety in the rural landscape. My gut feeling is that the loss of dairy farms across the UK, but particularly in the SE, is part of the problem as cow dung =insects, in my observation! If only we could grow wildflowers on just 2% of our farmland, the results would be spectacular.
Ironically, it is the suburbs and towns that now provide the mix of flowers that bees, butterflies need for nectar , and essential minerals. If one wants to attract them and attract birds, who eat the insects, and seeds, it is easy! Just plant a number of flowers and shrubs that have flowers, and give flower for as long as possible ! Avoiding only a very few double flowers that stop access to the nectar, the only real rule is to plant a mix of plants with a variety of flower colours …. blue , yellow, white, red, pink etc etc. The plants don’t have to be native plants, but can be very ornamental. I often see bees and butterflies on laurel leaves, harvesting honeydew or sap that presumably give them minerals or sugars they need for life. I have a particular variety of Rosemary called “Severn Sea”, which flowers for months and months in Spring, Summer, and even in late Autumn. It is always covered in bees! Oh… nearly forgot …. the normal, common or garden buddleia lives up to its name of “butterfly bush”.
Can I make a quick plead to fellow Inside Croydon readers who have a garden or window box?
If you have a lawn, it is easy to create a mini wildflower meadow “island” by leaving an area unmown (in fact, cut once per year) , and planting within it a number perennial native UK wildflowers, whether pot grown, or in “plugs” (small fibre pots” ) or cast some UK wildflower seeds over part of the lawn. The wildflower species need to be suitable for meadows, so would include a number of colourful and attractive low-growing plants like cowslips, horseshoe vetch, birds foot trefoil and others, and knee-high plants, like ox eye daisies, campion and scabious. There are several suppliers of UK native plants , with websites and good advice. Yellow Rattle seeds will help help encourage the other wildflowers by reducing the vigour of the grass.
The area will need cutting just once a year, in November, or December, when the cut grass and dried up stems of the wildflowers will need to be raked off and put in the compost bin . Only 2 rules– don’t add fertiliser, and don’t leave the grass cuttings on, as they will rot down, and stifle the growth of new wildflowers in the Spring. The ideal is to have two meadow areas like this– one is left uncut one year, and the other is cut only once. Next Autumn, cut the uncut one, and leave the other. Butterfly eggs adhere to the plants, and fall to the ground, so this will
In my own garden I have made two of these “wildflower meadow islands” –each no more than 2 m wide by 1.5 or 3 m long. They are islands within the normally mown lawn– a lovely contrast between the smooth carpet of lawn, and the varied textures and colours of the mini-meadows. The meadow areas are constantly visited by bees and, when the sun comes out, in Spring Summer and Autumn, by butterflies and some beautiful moths too. The beauty of the flowers , from the first cowslip in early Spring, through to the delicte,mauve lacey pom poms of the last scabious flowers in November, and the decorative seedheads of grasses and wildflowers, give the garden so much interest, and an amazing vitality. What’s good for bees is good for butterflies, and birds too. I suspect that a fox likes to sit and sunbathe when we are not around-as well.
If you are window box gardener, any flowers will attract bees and, if they are present locally, butterflies too.!
When it comes to encouraging wildlife, any flowers are good for nature.Every little helps!
Lewis White
( a landscape architect living in Coulsdon)