What's Happening in August 2011

Now that the holiday season has arrived and the weather is more settled, there is every reason to visit some DWT reserves in this, our 50th Anniversary year. My own progress in the ‘42toDo Challenge’ has been modest with just 24 visited so far, but the variety and richness of our reserves is impressive and I’m looking forward to completing the challenge.

Where are all the butterflies?

Although buddleia is now in flower, the number of summer generation red admiral, peacock and small tortoiseshell butterflies feeding on this abundant source of nectar has been disappointingly low so far. Will numbers increase in August?

By contrast, the spectacular silver-washed fritillary is doing well, and on a recent visit to Girdler’s Coppice these large butterflies were swooping along the rides and chasing other butterflies before feeding on marsh thistles and betony. Once mated, the females investigate shady areas with violets and normally lay their eggs on the lower trunks of oak trees. The following spring, the small caterpillars will descend to the ground to feed on the leaves of the violets.

A beautiful friendship

August is also the month to look for chalkhill blue butterflies. The males with their light silvery-blue colouration are quite unlike all other species of blue butterflies. Typical of chalk and limestone downs where horseshoe vetch grows, the chalkhill blue is now scarce in Dorset. Search for them on the Isle of Portland, Bindon Hill, Badbury Rings, and our DWT reserve at Fontmell Down. The caterpillars and chrysalis are protected by ants and in return, the ants get a plentiful supply of honeydew containing sugars and other important nutrients which are exuded from glands on the caterpillars.

Even birds holiday in Dorset

In July and August the southerly migration of many wading birds is already well underway. They are attracted to their northerly breeding grounds because of the long summer day length for feeding and lower death rates from predators. Our DWT reserve at Brownsea provides good viewing opportunities, as do Ferry Bridge and Christchurch Harbour. In addition to species such as greenshank, spotted redshank and black-tailed godwit, look out for the smaller dunlin and ringed plover, some of which will have bred in the high arctic and may winter in Britain, or continue further south to West Africa.

There has been effective publicity about the south-bound migration of five adult cuckoos tagged with tracking devices by the British Trust for Ornithology this year. They all left England in July and four have already made it to sub-saharan Africa. However, their offspring, hatched and fed by surrogate parents such as meadow pipits and reed warblers will still be in the UK. I can recall a pair of meadow pipits flying after a young cuckoo and feeding it as it moved about my local heathland in August.

Garden favourites

As post-breeding mixed flocks of resident blue, coal and great tits, together with goldcrests and occasional nuthatches and tree creepers work their way through our deciduous woodlands feeding on small insects, they will be joined by migrating willow warblers this month. Listen for snatches of their delicate descending song. Before long they will be gone until next year and the closely related chiffchaff will take their place for a month or two before most of them also leave our shores.
Most summer-flowering plants have now come into bloom, and there are relatively few special plants, such as autumn ladies tresses, autumn felwort, devil’s-bit scabious and marsh gentian to look forward to in the next few weeks.

Butterflies, bees and hoverflies- oh my!

However, there are plenty of common plants currently in full bloom which attract a wide variety of insects including butterflies, bees, hoverflies and beetles. Amongst these, take a close look at the insects associated with common ragwort, hemp agrimony and brambles.

Honey bees, and many different species of both solitary and bumblebees are all active at this time of the year and are fascinating to watch. The latest copy of Dorset Wildlife offers a useful introduction to this important group of insects.

Not marmalade for your toast!

And finally, you will almost certainly see the wonderfully named marmalade hoverfly! This harmless species mimics a solitary wasp and is commonly found feeding on nectar on flat-topped flowers. These are really useful insects in the garden because their larvae feed on aphids.
 

Written by John Wright
Dorset Wildlife Trust Member & Volunteer

Silver Washed Fritillary Male - Ken Dolbear

 Chalkhill Blue - Ken Dolbear

Dunlin - Ken Dolbear

Willow Warbler - Ken Dolbear

Bumblebee - Ken Dolbear

Hoverfly - Ken Dolbear