Regional differences in UK butterfly count

Big butterfly count results: Country by country
Courtesy of Butterfly Conservation.
September 2010. There are many similarities in the big butterfly count results across the UK, but also some interesting differences. Of course, not all species occur in each country, but among butterflies and moths that are widespread the data you collected show some notable patterns.

The Top 10 most abundant species in each UK country were as follows:

The Small Tortoiseshell seems to be faring relatively better in the north than in the south: it was the fourth most common butterfly in Scotland but only the ninth in England and Wales.

One interesting finding concerns the Small Tortoiseshell. Although its appearance in the Top 10 suggests that this beautiful butterfly has recovered from recent population crashes, sightings varied across the UK. The Small Tortoiseshell seems to be faring relatively better in the north than in the south: it was the fourth most common butterfly in Scotland but only the ninth in England and Wales. This north-south divide is also evident across the English regions.

The Gatekeeper was a surprise third place overall in this year's big butterfly count. This butterfly does not occur in Northern Ireland or Scotland, so it reached this place in the rankings based on the numbers seen in England and Wales alone.

Welsh counters see more
Another, not altogether unexpected, result concerned the number of butterflies and day-flying moths seen by big butterfly count participants in different countries. On average, each person in England and Wales counted more insects than participants in Northern Ireland and Scotland. In Wales people noted 24 butterflies and moths on average and in England the average count was 21. However, in Northern Ireland people noted only 16 on average and, in Scotland, 12. This reflects geographical differences in the diversity and abundance of butterflies and moths but may also be influenced by variation in the proportions of counts that took place in different habitats. In spite of these differences between countries, even seeing 12 butterflies is pretty good going in a 15 minute count.

The Green-veined White performed particularly well in Northern Ireland and Scotland in relation to England.

Other variations
The Green-veined White performed particularly well in Northern Ireland and Scotland in relation to England. People who sighted of this butterfly (which does not attack cabbages!) in Northern Ireland and Scotland counted eight individuals on average, but participants in England saw only four on average and those in Wales five per sighting.

In Wales, it was the Common Blue that impressed, coming in fourth place. Participants saw a greater abundance of Common Blues in Wales than in the other countries. Welsh participants saw eight Common Blues on average, twice as many as participants in England and four times as many as those in Northern Ireland.

Big butterfly count results: English regions

North - South divide

The most dramatic result was the north/south divide in the performance of the Small Tortoiseshell. Amazingly, the Small Tortoiseshell was the second most common butterfly in North East England, and also did well in the North West (seventh place) and Yorkshire and the Humber (seventh place). In stark contrast, in South East England the species came a miserable 18th place and it fared little better in East of England (15th place) or London (13th place). Those who saw the Small Tortoiseshell during big butterfly counts in the North East recorded an average of six individuals whereas those in the South East encountered an average of only two butterflies.

Moths seemed to fare very well in the East of England. Two moths made it into the East of England Top 10, the Six-spot Burnet (fifth place) and Silver Y (seventh place) whereas no moths were in the Top 10 for any other region! What's more, people who recorded the Silver Y in the East of England saw an average of six individuals whereas those in other regions saw only two or three moths on average. The Silver Y is a highly migratory species that sometimes arrives in huge numbers so perhaps there had been an influx into eastern England around the time of the big butterfly count.

The performance of the Gatekeeper is again worthy of mention. It was the most common butterfly in North West England, as well as in the North East, South East and in London.

The performance of the Gatekeeper is again worthy of mention. It was the most common butterfly in North West England, as well as in the North East, South East and in London. The numbers seen in the capital were particularly impressive with almost twice as many Gatekeepers counted in London as the next most common butterfly, the Small White. In the 1980s, the Gatekeeper was only found around the fringes of London, but it has gradually been spreading into more urban areas helped, perhaps, by more wildlife-friendly management of parks and gardens. The big butterfly count provides further evidence of this trend, with Gatekeepers reported from Regent's Park and Clapham Common, as well as many of London's outlying green spaces.

Tigers prowling London
Another species that appears to be doing well in London is the Jersey Tiger moth. Although not one of the 'target' species for big butterfly count, many of you kindly let us know about your sightings of this spectacular moth which flies by day and at night. Jersey Tigers have traditionally been confined to south Devon and the Channel Islands, but in recent years they've expanded their range in the West Country and also become established on the Sussex coast and the Isle of Wight. There had also been a few sightings in Forest Hill, south London, much to the surprise of experts. However, big butterfly counters recorded a substantial increase in London in 2010. Jersey Tigers were reported much more widely in the south London suburbs, from Thornton Heath right up to Kennington, just a few streets away from The Oval cricket ground and a stone's throw from the River; the moth is clearly spreading its wings and establishing itself further afield.

More people took part in the South East than in any other English region, but all regions had a good coverage of participants. The South West, however, was the place to see the greatest number of butterflies - each big butterfly count participant saw an average of 24 individual butterflies and moths in 2010, slightly ahead of the South East and Yorkshire and the Humber, where people counted at total of 22 on average. The abundance of butterflies seen declined in the far north and also in London, which had the lowest average count (11 individual butterflies and moths).

Carry on counting
It will be fascinating to see how things change region by region in the years ahead. Species such as the Gatekeeper, Comma, Small Skipper and Ringlet are expanding their ranges, almost certainly in response to climate change. Many others are in decline. We need to keep our finger on the pulse of nature so make sure you take part in big butterfly count 2011.