BUTTERFLY CONSERVATION UPPER THAMES BRANCH
The Adonis Blue in 2007
Maureen Cross & Nick Bowles
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Though this year’s broods began as usual in May with a reasonable first brood, the second brood in August and September was poor compared with the excellent summer brood of 2006. Though it’s easy to put this down to poor summer weather the exact link between cool wet weather and less Adonis Blue butterflies is not understood. The larval food plant (Horseshoe Vetch Hippocrepis comosa) seemed to respond to the weather with stronger growth.
Conceivably the cool conditions directly prevented the development of the earlier stages, though the interaction that these stages have with ants means that it might have been the ants that suffered directly and thus this butterfly species suffered indirectly, as a result of fewer crucial interactions with ants.
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Two sites produced a first sighting of the species. One of these seems to have a small breeding colony while the other returned a single sighting (as many parts of the Berkshire Downs do). These regular single sightings arise as certain individual butterflies become vagrant; moving away from their breeding sites and wandering across the hills, loitering in fragments of better quality habitat as they go.
Equally two sites with previous records returned none this year. One is a site that probably just holds the odd vagrant in better seasons. The other had previously seemed a strong colony.
So despite a set back to the recent trend of slow expansion in the numbers and the range of this species, the overall picture was not one of a major collapse. Berkshire remains the county with most colonies and the largest colonies, though there are some colonies in Oxfordshire and Buckinghamshire.
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The 2006 distribution of Adonis Blue within the UTB area (Records from Levana) |
Maureen Cross & Nick Bowles
October 2007
