Green hairstreaks at Barnack Hills and Holes

On the way back from a site survey in Cambridgeshire, I had the opportunity to call by and take my lunch break in Barnack Hills and Holes in the sunshine. Having seen a photograph posted by Nottinghamshire Wildlife Trust the previous day, I knew that green hairstreaks were on the wing so I went off in hunt of these iridescent little jewels!

Green hairstreak (Callophrys rubi) can be hard to track down for a few reasons; firstly, they are wonderfully camouflaged against the leaves – seeing one at a flower can be almost like noticing that one of the leaves is drinking! Secondly, their populations can be small – some colonies are only a few individuals strong and so tracking them down on a large site could be time consuming.

IMG_5318
Spot the hairstreak drinking from the hawthorn flower!
Luckily, after a pleasant half an hour wandering through the cowslips and orchids, I came across several on a hawthorn shrub. It was a windy but sunny afternoon and this hawthorn bush was more sheltered than many others. When in flight, the butterflies reveal the brown uppers of their wings making them easy to spot on the wing – but they always rest with their wings held together and blend beautifully into the greenery.

IMG_5301
Green hairstreak amongst the hawthorn leaves
I watched two males take up sentry posts, settling on hawthorn buds or leaves, poised to leap into action and defend their territory against intruders. Other males were the most targets likely to be chased, along with other insects and butterflies of other species, but they also use this vantage point to spot females on the wing. When resting and waiting, these males tilted their wings towards or away from the sun, micro-managing their temperature with these movements.

IMG_5454.jpg
Male green hairstreak poised on a hawthorn bud ready to intercept intruders
Green hairstreaks are widely but locally distributed in the UK – this means there is likely to be a colony somewhere near you but they have particular habitat requirements so you might need to go to just the right place to find them. They occur in a range of habitat types including dry heathlands, grasslands, old railway embankments, woodland and quarries. The key habitat requirement seems to be open grassland with a good scrub component. Adult food plants include trefoils, vetches, hawthorn, gorse and spring flowers such as cowslip and bluebell. The larval food plants are similarly diverse including trefoils, dogwood, vetches, gorse and broom.

IMG_5389.jpg
Green hairstreak on a hawthorn flower – one of the favoured food sources for the imago (adult butterfly)
These butterflies are on the wing early in the year – often in April and early May through to early-June or perhaps later in the north. Barnack is a great place to spot them but this site can help you find a location near you!

IMG_5507.jpg
Green hairstreak standing guard over his territory on a hawthorn flower
Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s