Colchester Natural History Society

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Watching Wildlife				Hillhouse Wood

August 2008

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August sees the start of the great avian trek southwards as birds which breed in Britain in summer but winter in Africa and the Mediterranean head for their wintering quarters and begin appearing along our coast, estuaries and reservoirs. Waders are already being seen at local birdwatch points such as Walton Naze; Colne Point; Fingringhoe Wick; Tollesbury Wick and Mersea Island as well as at Abberton Reservoir. My wife Linda and I saw three common sandpipers tripping along the edge of Abberton Reservoir on August 2 and at Tollesbury in first week of the month greenshanks, curlew sandpipers and whimbrel were among the waders being reported.

Time to take a closer look at the butterfly and moth season so far. Those of us running moth traps and lamps are finding lower numbers both of totals and species with often single examples where normally in summer there would, be 20 or 30 of a particular species. But, as ever, with moth trapping there’s always the possibility of an exciting arrival. This was the experience of David Barnard, the CNHS hon treasurer, and an enthusiastic member of Essex Moth Group who runs an MV lamp and trap in his garden at Alresford. On the night of July 15 there were 11 species of macro moths and several species of micro moths and among them was a moth new to Essex. It was a beautiful snout, a small moth included in the "macros". The nearest place where this uncommon species occurs is Kent but it is mostly to be found in the south and south-west of England where its larval foodplant, bilberry, grows. Bilberry is not found in the wild in Kent and it is suspected that there the moth may be using heathers as larval foodplants.

CNHS Vice President, Ian Rose, another enthusiastic moth lamp operator, also logged a "first" for NE Essex when a rosy marbled moth landed on his sheet at Tiptree Heath on the night of June 4. This species is now found in heathy areas of woodland and on heaths where its larval foodplant tormentil, grows among heather and bracken and as far as we know Epping Forest and Thorndon Park are the only sites, apart from Tiptree, where there are colonies. The Tiptree record shows the value of survey work being carried out by CNHS and Essex Moth Group members.

A very mixed situation regarding butterflies in NE Essex. There have been good numbers of meadow browns, ringlets and, in particular, gatekeepers and the first brood of small heaths was plentiful in places such as the Woodland Trust's Fordham Hall Estate and at Copt Hall, Little Wigborough. However the normally plentiful and widespread speckled wood was not all that common in the first brood and only a handful of first brood records for the wall brown which is now considered almost a rarity after being once a common and widespread species. It does seem to have better second broods so keep a watch in August and September. In the past Walton and Frinton produced second—brood records.

White admirals were seen in reasonable numbers at Stour Wood, Wrabness and Friday Wood, Berechurch in July but, once again, only a disappointing number of small tortoiseshell records. It is now established that small tortoiseshell larvae are being attacked by a parasitic wasp which has arrived from the Continent so this may be one of the factors behind the species' decline.

There's anxiety, too, for the white-letter hairstreak. This year elm disease is rampant and killing some of the trees which this very local butterfly depends upon for survival as its larvae feed on elm leaves.

It’s not a good year for migrant butterflies and moths. I have had only a handful of reports of painted ladies and, so far, no records of clouded yellows. The usually common immigrant silver-Y moths are only singletons and the same goes for the hummingbird hawk moth with records from Mistley, Tiptree and Bradwell-on-Sea (2).

August is when our area salt marshes are bright with the blooms of sea lavender and sea aster. Sea lavender is not only a marvellous nectar plant for butterflies and many other insects, it is also the caterpillar foodplant for a tiny plume moth, the salt marsh plume Agdistis bennetii, The sea aster, as well as an important nectar plant with its blue and yellow—centred “michaelmas daisy” blooms, provides food for the
green and yellows-striped larvae of the starwort moth.

BUTTERFLIES UPDATE

By end of the first week of August, when there were suitable sunny days, good numbers of second brood common blues were on the wing including
the High Woods Country Park meadowlands; Fordham Hall Estate meadows; Copt Hall, Lt Wigborough and Marks Hall, Coggeshall. Second brood brown argus flying at Copt Hall, Marks Hall and Fordham Hall Estate with second brood small heaths. Peacock numbers increasing with 20 at Copt Hall nectaring on bramble blooms and thistles.

Barbara finds a rare vagrant moth

Barbara Lock, a member of Essex Moth Group, had a rare and exciting arrival to her Frinton-on-Sea garden light trap on August 25. It was a dark crimson underwing Cotacola sponsa, only the third confirmed Essex record for this rare vagrant. It is not a resident species in Essex but is found only in oak wodland in Hampshire and Sussex where it enjoys Red Data Status. Elsewhere it is considered a rare immigrant. The previous Essex records were Bradwell-on-sea in September 1951 and at Hainhault pre-1903.

The female beautiful snout moth Hypena crassalis which came to the moth trap operated by David Barnard in his Alresford garden on the night of July 15. This is the first record for Essex OF this species which is found locally in southern and south west England where its caterpillars feed on leaves of bilberry. David's moth could have strayed from Kent, nearest colony, to Essex or may have been an immigrant.

Photo: David Barnard.

Lots of peacock butterflies on the wing this month, twenty were counted on thistle blooms and bramble blossom at Copt Hall , Lt Wigborough and similar numbers reported on sunny days at several other sites in the Colchester area.

Photo: Joe Firmin.

Wading birds are moving south to winter quarters in Africa and the Mediterranean in August. Common sandpipers regularly seen at Abberton Reservoir and Fingringhoe Wick.

Essex is famed for its salt marshes and in August they are bright with the purple blue flowers of sea lavender. The plant is host to a tiny moth, the salt marsh plume.

It's been yet another poor year for the wall brown butterfly with only a handful of sightings of the first brood. A second brood flies in August into September and can be seen along the cliff slopes at Walton and Frinton.

August sees the start of bird migratory passages along the Essex coast and Walton Naze is a good site to look for pied flycatchers in the bushes and scrub. Female pictured.