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Birchanger Wood Moth Survey: the Results

Jono Forgham

 

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Graeme J Smith, Steve Easby and Jono Forgham of Herts Moth Group set up three light traps within the wood around 8.30pm on the Friday night for a public moth night. Local residents were invited via the Birchanger Wood website and Facebook account, posters within the wood and a mention in the local newspaper.

In total, around 20 people turned up, including four children. Jono gave a brief introduction as to how the traps work and a little on the biology of moths, detailing their evolution and that there are two large groups of moths, split into micro moths and macro moths. The temperature was perfect for a late May night and by 9.15pm the group began wandering around the wood. The children were given pots and a net to see if they could catch any early fliers and the first moth to be taken was a Nemapogon cloacella, the Cork moth.

The traps consisted of 2 Robinson type traps with 125W mercury vapour bulb powered by inverter generators and a smaller Heath type trap running off a 12 Volt battery with a 15 watt actinic tube.

Mothing was slow as it appeared to be quite dark, but a look to the sky proved that it was still too light for most moths, especially the macros to be on the wing. This was a shame as it was getting too late for the children who had to leave around 10pm and it was shortly after this that moths became more apparent, roosting on the sheets that had been set adjacent to the traps.

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Illustration of a Pipestrelle bat preying on a moth. Picture courtesy: RSPB

By now, bats could be seen flying, especially around the open spaces of the water tower. Jono had brought his bat detector that amplifies the sounds bats make to guide their flight. By setting the device to a specific frequency the bat can be identified to species by the sound and also by the kilohertz range. These bats were within the range 45 – 52KhZ which showed they were Pipestrelle bats. A larger bat was seen flying within the wood but had disappeared before the detector could be set to the correct range.

By now the group settled around one of the larger traps and Graeme and Jono talked folk through the species. At this point the highlight of the night for most of group made an appearance, a large female Poplar hawkmoth. Other good moths seen included a Figure of 80 and a Brindle white spot, the latter being an uncommon moth for East Herts with only a few records for Bishop’s Stortford, being more common within Broxbourne Woods further south. A moth that uses oak, lime and birch as its larval foodplant.

It was then decided that the traps should be checked, so the group gathered around each trap in turn as the moths were checked roosting on the egg boxes placed inside the traps. They were all counted and listed.

In total, a somewhat disappointing 106 moths of just 32 species were recorded. We had anticipated twice as many but packing up by midnight meant we missed a good selection of the late flyers. Another trapping night towards the end of July will offer a much wider selection of high summer species in considerably larger numbers. However, all that attended seemed to have enjoyed the evening, seeing many moth species for the first time.

Our next event is the Bug Hunt on 22nd June, from 11am to 1pm – meet at the compound by the water tower, Heath Row, Bishop’s Stortford.

 

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Birchanger Wood Moth Survey, 31 May 2019

SPECIES NUMBER OBSERVED
Micro
0125  Emmetia marginea 2
0140  Nematopogon swammerdamella 5
0148  Nemophora degeerella 1
0216  Cork Moth (Nemapogon cloacella) 30
0224  Triaxomera parasitella 1
0343  Phyllonorycter esperella 1
0417  Argyresthia spinosella 1
0648  White-shouldered House Moth (Endrosis sarcitrella) 3
0661  Pseudatemelia flavifrontella 1
0921  Phtheochroa inopiana 1
0986  Syndemis musculana 1
1082  Plum Tortrix (Hedya pruniana) 2
1174  Epiblema cynosbatella 1
1176  Epiblema trimaculana 1
1392  Udea olivalis 1
1428  Bee Moth (Aphomia sociella) 4
Total Micros 56
Macros
0017  Common Swift (Hepialus lupulinus) 20
1654  Figure of Eighty (Tethea ocularis) 2
1727  Silver-ground Carpet (Xanthorhoe montanata) 2
1728  Garden Carpet (Xanthorhoe fluctuata) 1
1764  Common Marbled Carpet (Chloroclysta truncata) 3
1776  Green Carpet (Colostygia pectinataria) 1
1819  Mottled Pug (Eupithecia exiguata) 2
1834  Common Pug (Eupithecia vulgata) 1
1875  Small White Wave (Asthena albulata) 2
1904  Scorched Wing (Plagodis dolabraria) 1
1906  Brimstone Moth (Opisthograptis luteolata) 1
1950  Brindled White-spot (Parectropis similaria) 1
1961  Light Emerald (Campaea margaritata) 2
1981  Poplar Hawk-moth (Laothoe populi) 1
2028  Pale Tussock (Calliteara pudibunda) 1
2064  Ruby Tiger (Phragmatobia fuliginosa) 1
2092  Shuttle-shaped Dart (Agrotis puta) 2
2380  Treble Lines (Charanyca trigrammica) 1
2441  Silver Y (Autographa gamma) 1
Total Macros 46
GRAND TOTAL 102

 

 

 

Completed Wood Store Will Boost Trust’s Funds

The Trust’s volunteers have been busy in recent months, building a new covered wood store in our compound off Heath Row to improve storage and seasoning of firewood for sale.

Cut wood from coppicing is stored in the new shelter, providing a better quality seasoned log that burns hotter and more efficiently with less smoke. Air can circulate around the logs, which are better protected from the elements. With a solid base for the logs to sit on, the store also reduces the possibility of a wood pile collapse and is therefore safer.

Wood sales contribute to funding the work in Birchanger Wood, helping to maintain this ancient woodlands for future generations. A second wood store is planned at our compound, subject to more fund-raising. More storage will mean increased income for the Trust, enabling it to meet its charitable aims and objectives.

Logs are sold to the public at our compound every Saturday all year round, between 9-10am and 2-3pm. Each barrow load costs £12.

Before and after

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A Case of Too Many Very Hungry Caterpillars

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Some visitors to Birchanger Wood have remarked on the massive number of tiny green caterpillars. Unfortunately, this Spring we are facing a massive invasion of winter moth caterpillars, which are chomping through young leaves on our trees. Hatching is timed to coincide with the budding of oak leaves, their favourite dish. They also feast on maple, birch, hornbeam, hazel and beech – all the tree species that can be found at Birchanger Wood. The large number of caterpillars is leading to the defoliation of many trees.

Hatching is determined by temperature. The moths are adjusting to climate change through selection with the larvae of the most adjusted eggs thriving. As the climate is changing in winter and spring, the winter moth is hatching earlier and earlier to synchronise with their main food sources. If the caterpillars hatch before the trees bud, then they will have no food source and will starve.

There is little we can do about the blight but hope that the birds will take advantage of this plentiful food source. Tits are known to predate the winter moth caterpillar and will feed them to their young. However, this will only work well if the peak wood moth caterpillar population coincides with the hatching of the tits’ eggs. Scientists have found that the birds are less able to adjust to the earlier peaking of caterpillar populations, which means they are often unable to take full advantage of the higher caterpillar population.

Research has found a mismatch emerging between caterpillar hatching and the hatching of woodland birds. Dr Karl Evans, from the University of Sheffield’s Department of Animal and Plant Sciences, told The Telegraph: “Our work suggests that as springs warm in the future less food is likely to be available for the chicks of insectivorous woodland birds unless evolution changes their timing of breeding.”

So, the problem isn’t going to go away easily. We can only hope that this is a bad year due to specific weather trends this Spring and that the trees will continue to bud new leaves after the caterpillars pupate.

If you are interested in moth identification and learning more about moth species in Birchanger Wood, please visit our events page.

The pictures on this page were taken today in Birchanger Wood.

 

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Coppicing Season Ends and Pat Starts Building

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Birchanger Wood warden Pat Forrest building a new wood store in our compound

The coppicing season has come to an end at Birchanger Wood. Volunteers have laboured hard over the winter to cut back trees to allow light onto the woodland floor, boosting the flora and helping to support biodiversity.

While it may seem counterintuitive to cut down trees for the sake of woodland conservation, coppicing is an age-old practice of harvesting trees for wood products – baskets, beanpoles, walking sticks, arbours, thatching, fences, charcoal and firewood. The practice of coppicing goes back to a time when society was heavily dependent on wood and woodlands were cared for due to their economic importance.

Many bird species rely on insects as a source of food and insects benefit from the flowers that flourish when the woodland floor gets more sunlight, unimpeded by the dense canopy of mature trees.

The trees themselves are not harmed and if they are protected from browsing animals such as rabbits and deer, they will grow back healthy – often with a longer lifespan than if they were left to grow as standards. However, the trees and flora can only thrive if walkers, cyclists and dogs keep to the paths.

In line with a management plan devised by conservation experts and overseen by our warden Pat Forrest, Birchanger Wood Trust is pursuing this time-honoured method of woodland management with sales of firewood from coppicing helping to sustain our work.

We are now boosting our capacity to coppice larger areas by training long-standing volunteers in safe chainsaw use and building a covered wood store in our secure compound. The store will improve the quality of firewood, which was being stored under canvass where it was more open to the elements.

We look forward to another summer watching our woodland benefit from continued management and developing a legacy for future generations.

We have a packed series of events led by local science educator and conservationist Jono Forgham – visit our events page for more details.