Notes relating to our Herts and Middx Purple Emperor studies to 2001

Liz Goodyear and Andrew Middleton saw Purple Emperor at four locations in Herts in 2001, unfortunately all on private ground this year. With luck we hope that a territory will soon be found where public access is not a problem. Although it appeared to be a good year for the species overall, no clashing males were seen at the location discovered in 2000, where sallow numbers were subsequently more than halved, and the frequency of sightings here fell to just 25% of the 2000 level.

Purple Emperor in Herts in 2001

Purple Emperor data from 1992-2001 is beginning to give a guide as to when best to go looking for Purple Emperors in Herts:

1. Recorded flight period 3rd July to 13th August
2. Multiple sightings 5th to 24th July
3. Clashing males 13th to 17th July
4. Watch sallows for female activity associated with egg laying 12:00-14:00hrs
5. Watch for male territorial activity at high points from 13:00hrs.

Points 4 & 5 have their origins in Ken Willmott's studies described in 'The Purple Emperor' booklet (Butterfly Conservation).

Patient and persistent canopy-watching in sallow-rich woodland could well be rewarded with sightings for more observers.

Appropriate and timely decisions regarding sallows in woods could tilt the balance in favour of Purple Emperor for many years to come, and several woodland managers are now considering the problem in full. Of all our endangered species of butterfly, it seems likely that Purple Emperor could be relatively simple to manage for on a less than annual basis, given the right decisions at the right time.

An important woodland complex with occasional sightings spanning many decades, and where positive management for the species is taking shape, is the Broxbourne Woods NNR. Paul Jarczewski, of Herts Countryside Management Service, is accommodating the needs of Purple Emperor in a very positive fashion at Broxbourne Wood: "It will be our intention, through management work, to keep any sallows we find on the edges of rides and glades and to encourage their development to maturity. We also plan to retain the strip of sallows running through the centre of the large glade in Broxbourne Wood. A scattering of sallows within this belt will be allowed to reach maturity in the hope this will encourage egg laying Purple Emperors."

Habitat management for Purple Emperor has also been put in place on the NNR by Neil Chamberlain of the Woodland Trust. When 4ha of regrowth in the Woodland Trust’s Wormley Woods was thinned in late autumn 2001, many sallows were retained, each with enough space to grow and mature over many years to come. It is very pleasing that the relevant bodies have responded so positively to suggestions from branch members.

Sightings by other observers are detailed in the Hertfordshire and Middlesex Butterfly Conservation Annual reports.

See ‘Targetting Species’ for more Purple Emperor details – species’ co-ordinators Liz Goodyear and Andrew Middleton