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Chorleywood and District Local Group Newsletter No. 87 August 2018

www.rspb.org.uk/groups/chorleywood

Group News

We hope that you have all enjoyed the hot summer. It will be interesting to see what effect the dry spell and excessive heat has had on our breeding birds. Certain foods will have been hard to find, such as worms. Water sources will have dried out. Birds need water not only for drinking, but to cool down, because they do not sweat.

Car Parking at the Russell School

The playground at the rear of the School is breaking Swallowtail butterfly as seen at Sutton Fen up and sinking, such that the children are not able Photo: John Markham to play on the worst parts. Therefore, all groups that use the School can now only use the front car park. Some of us visited in June, where Edward We can double-park there for the duration of our Meyer of Swift Conservation was speaking. He led meetings. The local streets are all residential, us on a walk at 9.30pm on a sunny evening to see though a little dark, and we suggest that a torch dozens of screaming swifts around a block of 1960s might be useful. The forthcoming programme of council flats. Again, they were very interested in Indoor Meetings, arranged by Mary Coulson, is swooping under the gutters and landing there. excellent and really not to be missed. Edward was of the opinion that they must have nests in this building. So do look each June, even in Outdoor Meetings the newer parts of town, and report your findings. Tony Wright has organised the Outdoor Meetings We aim to write to Three Rivers Council to ask for 10 years and we owe him a lot, because through them to do all they can to help swifts when these meetings we learn an enormous amount maintaining their buildings. One of us has about the natural world. ‘Thank you’, Tony. We are purchased two swift nesting boxes and we will keep glad to hear he is happy to continue! you all informed about the progress of this. The Committee Swifts Some of us have been looking for swifts in and , with surprising CONTENTS results. The older buildings of the town are not Sutton Fen ...... 2 attracting swifts. We think a block of 1960s flats is Head Start for Black-tailed Godwits ...... 2 hosting a nest. The new housing estates near New Beetle Book ...... 3 Leisure Centre and the housing in Maple Lodge Latest News ...... 4 Tudor Way seem to be very popular with screaming Scientific Study on Feeding Birds ...... 5 bands of swifts. They cling to the rough brickwork Your Photos …………………………………5 and look under gutters. Group’s Garden Birdwatch Results ...... 6 Outdoor Meetings Reports ...... 7

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A ‘Thank-you Event’ for RSPB areas where damselflies, dragonflies - hawkers and Volunteers at Sutton Fen chasers - were in abundance. Swallowtail butterflies were everywhere. This is one of the

feature insects of this area of the Norfolk Broads This Reserve on the Norfolk Broads is not open and it was almost a relief to see two brimstone to the public. Volunteers were invited for the butterflies and a few meadow browns. Whilst rare opportunity of a guided walk. wending our way back to the car park, a cuckoo

was briefly seen, also a hobby and a few swifts. Sutton We arrived back at the cars at 1pm and thanked the Fen volunteers and Richard for a very interesting Photo: morning on this exclusive reserve. Ben Hall

Fen orchid at Sutton Fen About 20 members from various RSPB groups in Photo: Thomas the Eastern region met at Sutton Fen RSPB Hanahoe Reserve for an event to thank volunteers from Local Groups. This Reserve is not usually open, so it was a real treat! Several local experts, each having special knowledge of butterflies, moths, dragonflies, bugs and birds, were on hand. Richard Mason, the Reserve Warden, specialised in plant life. But we didn’t need to have a barn owl, which was hawking across the meadow, identified for us! Irene Oulsnam June 2018 A swallowtail butterfly pupa had been found the previous day and was being monitored and kept in an enclosure until it metamorphosed. We walked across a meadow to the boggy area. Here the ‘Headstarting’ Black-tailed Godwits vegetation, consisting of peat, sphagnum moss and WWT Welney the plants growing on it, rested as a blanket on deep water, which was fed by a flowing river deep Breeding success on the washes has been beneath. This was once a large lake, which increased by egg removal and hand rearing eventually became colonised with reeds and other plants. My visit to the Wildfowl & Wetlands Trust Reserve at Welney was to hear about the ‘headstarting’ of The main plant of interest was the very rare Fen black-tailed godwits. These waders are in decline Orchid. It was thought to be extinct in the UK. But in as breeding birds in this country. So, to give the 2006, when the site was bought by RSPB, they population a boost, the Trust, together with other found 400. This year a small transect produced conservation bodies like RSPB, collect eggs from 4,000, and when Plantlife UK does a survey of the the nest and incubate them. The chicks are then rest of the bog, it is hoped the total count will be reared and kept in large enclosures until they are around 20,000. It is a very small orchid, standing old enough to go out and fend for themselves. only about 8” tall with very small greenish white flowers and it could easily be overlooked amongst The godwit lays on average four eggs and all the the taller grasses and flowers. eggs are collected early morning when the bird has left the nest to feed. Dummy eggs replace those A marsh harrier made an appearance and a bittern taken and she will return and continue to sit on the flew over much to our surprise. We walked back nest. Next day the volunteers go early whilst the through the meadow where early marsh and bird is still on the nest and gently lift her off, note southern marsh orchids were in profusion. The next any leg tags she has, or if she hasn’t, then tag her bit of the walk was along a path through watery so that a record is kept from which female the eggs 2

were taken. (Like the butcher knowing which animal Headstarting will dramatically increase the number of his meat source is from.) Because of the flooding young black-tailed godwits that fledge in the UK this of the Ouse Washes this year not so many nests summer. The surrogate human ‘parents’ have been survived. However, enough eggs were collected able to safely raise far more chicks than the godwits over a staggered period of time and the first ones to themselves, away from the dangers of predators and hatch have now been released. The next batch flooding. Crucially, by removing the eggs from their were in the holding enclosure ready to be released nests early, they have prompted each pair of godwits shortly. to lay a second clutch giving the parent birds a chance to raise a brood of their own. We were taken by vehicle to the far enclosure – still Irene Oulsnam a long way away – to try to see some of the earlier released birds which stay around the enclosure for a short while. It was difficult to see any as the reeds and vegetation were tall and one needed to be 6 ft. to see over the top. We were told that within the next few days, 15 chicks from the enclosure would be taken for release in the Nene Washes to spread the population. Black-tailed godwits from earlier releases have migrated safely and have been recorded back on the Washes. One pair produced chicks on their return a year later. A great success story after a lot of hard work! Black-tailed godwit Photo: Pete Coulson

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Beetles of by Trevor James

A New Herts Natural History Society (HNHS) Publication - June 2018

This is a ground-breaking new book - the first published account of a UK county’s recorded beetle species to be accompanied by detailed information on their occurrence, habitat needs and conservation status. In 496 pages, more than 600 colour photographs illustrate a group of insects whose intricacy and beauty are too easily overlooked.

The book considers beetles in the context of conservation and their incidence as indicators of ecological health. So far, 2,483 species have been reliably recorded in Hertfordshire. The author, Trevor James, has been the County Recorder for beetles in Hertfordshire for 35 years. He is also the author of Flora of Hertfordshire 2009, also published by HNHS.

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Maple Lodge Nature Reserve bittern, osprey, great white egret, kingfisher, great Supporter and work party volunteer, Evelyn crested grebe, barn owl, siskin and song thrush. Fox, keeps us up to date with this Also, we have a pair of sparrowhawks that have Rickmansworth haven been nesting on the reserve for three years. Here is one of Martin’s photos of the female. There is a small private Nature Reserve in the WD3 area and it is rather a gem. It is situated in a line of gravel pit lakes in the Colne Valley and is 40 acres of mixed habitat that includes two lakes. Thames Water owns the site and leases it to the Maple Lodge Conservation Society. It was a sewerage settlement site over 30 years ago, which made the soil very fertile. This, along with its sheltered position, means vigorous plant growth and plenty of insects and other invertebrates. Female You enter the Reserve through the clubhouse, Sparrowhawk which includes a hide that overlooks Clubhouse at Maple Lake. The bird feeders are stationed there. There Lodge Photo: Martin are seven more hides positioned around Marsh Parr Lake and one that overlooks farmland. Several Open Days and Walk & Talk Days are held throughout the year. An Open Weekend is held in May and Discovery Day in August. There is Bat and Moth Night in the autumn, Fungus Day with a Wildfowl Walk in winter and Insect Day in June. Our last Insect Day yielded lots. Our small overgrown pond contained quite a number of tiny This has been a better year for song thrushes in our creatures, which our expert, Jane Archer, was able area this year. Although there are enough areas of to name. Some were larvae which, in time, will damp woodland with plenty of cover, we've usually become insects flying around the Reserve. A had only about two territories. But this year we have European hornet was also found. Overseeing all had about four. This is in spite of our Bird Recorder, this was Martin Parr, our Conservation Officer, who Paul Lewis, seeing a sparrowhawk take one, just said that all the dragon and damselflies recorded in outside the Reserve this spring. He explained he Hertfordshire had been found here. He had a beetle had seen film of a study, which shows that the expert with him who was able to identify forty new female does her hunting well away from the nest. beetles to the Reserve. This could be true because our female had been seen taking starlings two or three miles away. The Martin Parr also organises the work parties. These male would be more adept at woodland hunting. are held on Saturday morning and Thursday afternoon. The main participants are retirees and I We have forty nest boxes, all of which are used, but usually attend on Saturday morning. New a few have had dead baby birds in, which may be participants are always welcome. There is always a due to the parents being predated. lot of clearing, weeding, raking, cutting and lifting, and after two hours we finish at the clubhouse for Please come along to an Open Day and have a tea or coffee. Clearing the meadow by the guided tour. The dates of these can be found at reedbeds, for example, has resulted in 2,000 events@ maplelodgenaturereserve.org Southern Marsh Orchids this year. Evelyn Fox Inside the clubhouse are displayed the members' photographs put together by Christina Bessant. The mammals that have been photographed are polecat, badger, fox, otter and muntjac. Mostly they are passage visitors with the permanent residents well hidden. The birds that have been photographed include common snipe, water rail, lapwing, heron, common tern, green sandpiper, 4

Feed the birds? Scientists highlight the risks of disease at garden feeders

In a report that came out in March 2018, scientists from the internationa l conservation charity, ZSL (Zoological Society of London), concluded that a number of serious diseases pose a risk to wild bird health at our garden feeding stations. Feeding particularly in the harsher winter months provides many benefits, but garden feeding, especially when hygiene is poor, constitutes a risk of transmission of some diseases.

This was a collaborative study in partnership with BTO, and Fera Science Ltd. They analysed more than 25 years of data on the occurrence of wild bird health threats, focusing on protozoal (finch trichomonosis), viral (Paridae pox) and bacterial (passerine salmonellosis) diseases. The results show that these three diseases have changed dramatically over the past decade, in terms of the species affected and their patterns of occurrence.

Both finch trichomonosis and Paridae pox (which occurs mainly in birds of the Paridae family, especially great tits), have emerged recently. They cause epidemics that affect large numbers of birds. Passerine salmonellosis - previously a common condition - appears to have reduced to a very low level.

When disease outbreaks arise, people are encouraged to report their observations (e.g. lethargy, unusually fluffed up plumage, or wart-like growths) to the Garden Wildlife Health Project, GWH, seek veterinary guidance and consider a temporary halt to garden feeding in order to encourage wild birds to disperse, reducing the risk of spreading the disease further. To report any garden wildlife health problems, see www.gardenwildlifehealth.org

Recommendations

Commenting further, co-author Kate Risley, BTO Garden Birdwatch Organiser, said: ‘We are calling on everyone who feeds wild birds to be aware of their responsibility for preventing disease. We would recommend offering a variety of food from accredited sources, feeding in moderation so that feeders are typically emptied every 1-2 days: the regular cleaning of bird feeders and rotation of feeding sites around the garden to avoid accumulation of waste food or bird droppings.

The full report entitled ‘Health hazards to wild birds and risk factors associated with anthropogenic food provisioning’ can be read in the Philosophical Transactions of the Royal Society B.

Your Photos

Slime mould, Enteridium lycopodon, or False puffball at Maple Lodge. Photo: Anna Marett

Male pheasant in the spring in John Swainson’s garden

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Chorleywood & District RSPB Garden Watch October 2017 to March 2018 (by John Smith)

This is the Group’s 12th Garden Birdwatch and we would like to thank the 18 participants for submitting their forms to enable us to monitor the wild birds in our area.

The study covered observations in Rickmansworth (5), Chorleywood (5), Amersham (3), Chesham (1), Mill End (1) and Maple Cross (1), Little Chalfont (1) and (1).

The weather this year was again mild during the first half of the survey. The second half was wet and towards the end extremely cold.

The total numbers of sightings were similar to those of two years ago when 19 people took part.

The woodpigeon figures were well up on last year and remained in first place. Redwing and fieldfare numbers similarly increased, probably under the influence of the ‘Beast from the East’ and the cold weather associated with it.

Further details as well as a list of our top ten birds will be shown on the notice board at our indoor meetings. This year we have again provided a Top Ten list comparing the RSPB Garden Watch results for Hertfordshire with those we recorded over the same time in January. The first five of the top ten are the same, with only a small change in their relative positions.

Just a reminder that it is important that we look after our garden birds by putting out regular supplies of peanuts, sunflower kernels and nyger seeds, as well as cleaning bird feeders and topping up the bird bath. Please read the article on page 5 on the dangers, responsibilities and benefits of garden feeding of wild birds.

I would like to thank everyone for their efforts and support and hope they will continue to monitor the birds in their gardens in the coming season.

We had a number of new contributors to the survey this year and it would be nice if this trend could continue.

I would also like to thank Irene Oulsnam for producing the sets of Birdwatch Forms and David Witton and Richard Livermore for all their help. Forms for 2018/19 season will be available at the September meeting or from me via [email protected]

Chorleywood Chorleywood Chorleywood Group Hertfordshire Group Group Jan 2018 Jan 2018 BGW Oct to Mar 2018 Oct to Mar 2017 1 Woodpigeon Woodpigeon Woodpigeon Woodpigeon 2 Blue tit Blackbird Blue tit Blue tit 3 Blackbird Blue tit Long -tailed tit House sparrow 4 Goldfinch Goldfinch Blackbird Starling 5 Long-tailed tit Long-tailed tit Magpie Blackbird 6 Magpie Starling Goldfinch Goldfinch 7 Great tit Magpie Dunnock Robin 8 Chaffinch Dunnock Starling Great tit 9 Starling Chaffinch Great tit Long-tailed tit 10 Dunnock Great tit Robin Magpie

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Outdoor Meetings

Slimbridge WWT Reserve Saturday, 20 January 2018 return here from Arctic Russia each year. All the Despite suffering from the cold and drizzle, we all birds are known to the researchers at Slimbridge by were delighted with the thousands of wild birds their beak markings. We were told of the struggle seen around the Slimbridge Reserve. By the middle going on to find out the reason for the decline in of February numbers of some species can begin to numbers of these small swans. Now reduced to decline as migrants start on their way to their only 60% of the numbers that 20 years ago used to breeding grounds. So the end of January was an visit Europe each winter. Sacha Dench has created ideal time to arrange a visit. This was organised by much publicity for their plight by her brave flight in a Peter Harman. He arranged for a short preliminary motorised paraglider, all the way from their talk by a volunteer to steer us in the right direction. breeding grounds to Slimbridge. She overflew Luckily for us, he told us that the tide was now high eleven countries and attracted a lot of media on the estuary and there was a large concentration attention. The routes of the birds as they negotiate of birds to be seen on the muddy fields immediately the many windfarms is now known due to GPS around the reserve. We therefore headed straight tagging. Research is continuing to find out why the out to the hides (some via the café, I have to admit). birds are often shot by pellets. See: www.flightoftheswans.org Over on the Tack Piece and from the Holden tower, It was a good day. Thanks are due to Peter Harman thousands of wigeon were grazing and these were who listed the 53 species of birds seen below. overflown by 100s of lapwings. One or two curlews Robin, mistle thrush, blackbird, dunnock, redwing, fed amongst the flocks on the ground. On the pools chaffinch, long-tailed tit, blue tit, great tit, crow, magpie, were shelducks, pintails, shovelers and teals, and in rook, Bewick’s swan, mute swan, greylag geese, white the distance, we saw two cranes walking in the fronted goose, Canada goose, barnacle goose, red- gloom. Most likely these had returned from their breasted goose, European crane, feral pigeon, wood- release sites on the Somerset Levels. Later on, pigeon, house sparrow, buzzard, tree creeper, gadwall, almost nothing was seen from these hides once the coot, moorhen, mallard, wigeon, shelduck, cormorant, birds had spread out. We had been given good tufted duck, teal, shoveler, pintail, pochard, water rail, advice. redshank, avocet, golden plover, lapwing, little egret, little stint, grey heron, curlew, oystercatcher, dunlin, great black-backed gull, herring gull, black-headed gull, common gull, great crested grebe.

The River Misbourne Valley Cranes Saturday, 17 February 2018 with This is one of our regular walks from Amersham, lapwing past Shardeloes and on to Little Missenden. The and wigeon good news was the weather, which gave us Photo: sparkling sunshine and light that glistened from Dave early morning frost. A bonus too, was that the river Smith flowed well after a period of low rainfall, which had left it dry at this point earlier on in the year.

We did not all follow the same route around the We headed out past the cricket ground towards the reserve. Some headed to the far reaches to lake where a pair of pied wagtails showed their Kingfisher Hide, from where we could see the flock preference for the artificial turf in the cricket nets to of barnacle geese grazing and golden plovers the acres of freshly mown grass. Careful nearby. Others went to South Lake hide. The less observation of the lake provided a good selection of hardy viewed the captive birds nearer to the Visitor birds, including heron, black-backed and common Centre. Some even stayed in the Visitor Centre, gulls amongst the flock of black-headed gulls, great such was the cold. crested and little grebes, coots, moorhens and Towards the end of the day the spectacular daily tufted ducks. Overhead, on the ground and in the feeding took place on Swan Lake. Here we had a trees, we saw several red kites and buzzards, often close-up view of the Bewick swans, who famously with their mobbing escort of crows. 7

The fields beyond the lake provided a few mistle sandpiper. But this one had less of a tilt and thrushes and fieldfares. Dropping down to walk by seemed to rely more on its sense of taste to locate the river allowed us to see some secretive gadwalls food in a rather muddier part of the Spring. and a very secretive goldcrest. Reasonable numbers of chaffinches, great, blue and long- tailed More satellite tracking of these Lemsford green tits were present throughout, while robins and sandpipers is planned and we await the results from dunnocks patrolled the stacked heaps of timber. the Warden, Barry Trevis. We reached Little Missenden and spent some time Tony Wright searching for the fabled flocks of hawfinches that have been in the area this winter. No success! But Spring in the Chiltern Hills we did see a flock of goldfinches. Saturday, 21 April 2018 Then it was time to retrace our steps through a We visited the Chiltern Hills, near Hughenden rather muddy valley, after spending an enjoyable Manor, , to see how spring was morning of classic Chiltern birdwatching. progressing. Following the talk from John Tyler, in Tony Wright which he suggested that we all look carefully at small details of the natural world, we looked at

flowers and insects too, eyes peeled. Lemsford Springs HMWT Reserve Saturday, 17 March 2018 Firstly, we visited the BBOWT ancient woodland The weather forecast for snow put people off. This reserve of Milford Woods. The name ‘ancient was unfortunate as it turned out to be a woodland’ means that the land has not been meteorological non-event, with not a single flake ploughed for at least 500 years, but has been settling on any of the roads! But one brave person, managed continuously as woodland. This does not who did attend, had the opportunity of spending mean that the trees are not felled periodically or uninterrupted time closely observing the birds in a that the existing trees might be particularly old completely undisturbed environment, which offered themselves. We noticed early on the presence of shelter for birds and birdwatcher alike. wood anemones, coral root bitter cress, dog’s mercury, primrose, hornbeam and sweet woodruff, Despite the comparatively benign microclimate, the and these plants are indicative of ancient woodland. small birds were keeping a very low profile with a The beech, whitebeam, oak and wild cherry trees blackbird and blue tit venturing out of cover. The were just coming into leaf. water rail was only identified by its distinctive bill, which popped above the vegetation as it moved around the reeds. Moorhens and mallards were Kestrel on more visible, moving amongst the watercress beds. Hughenden Church The resident little egrets and grey herons spent Photo: Alan Yuen much time hunched against the light snow that fell on the relatively warm waters of the Springs. Herons would wait for their prey to come into range, whilst the egrets prodded and probed the clear water in search of food items.

However, the stars of the Lemsford show in winter are the green sandpipers and two were still in residence. They were constantly feeding. When one stopped and remained motionless, it attracted my It was difficult to see birds as the canopy was tall. attention. After about five minutes standing like this, But we heard many blackbirds and wrens singing it opened its beak widely several times, before loudly, with the odd chaffinch, blue tit and great tit regurgitating what looked like a snail. One wonders too. Kites and buzzards called around us. Of how it extracted the creature from its shell, as this course, woodpigeons abound here. In the seemed to be intact! surrounding fields and hedgerows, skylarks and jackdaws were seen, as well as the hovering On returning to feed, this bird displayed a definite beeflies, mentioned in John Tyler’s talk. optical sidedness while looking into the water. It tilted its head so always looked down with its right The open parkland gave us good views of red kites, eye, while scanning the sky with its left eye. This which are used to people here. One was bathing in behaviour was also demonstrated by the other 8

the chalk stream. The kestrel, which liked to use the Disappointingly, we saw no blue butterflies and church gargoyle as a viewing platform, was certainly no rare Adonis blues, which have been unphased by the numerous passers-by. Crows, seen at Yoesden. The chalk grassland plants jackdaws and goldfinches were around here too. included many common spotted and pyramidal We then walked through the high beech forest orchids. Kidney vetch abounded and milkwort, in surrounding Hughenden. The ground flora was blue and pink, along with the delicate fairy flax. sparse due to the dense beech canopy. However, on emerging into the open downland, we began to see a few early butterflies: small tortoiseshell, peacock, various whites and an unidentified ‘blue’. We heard a blackcap too. Great tit, wrens and blackbird calls were everywhere and two jays were seen on the woodland edge. Many holes on the path, around 0.5cm across, puzzled us, but we think that they were made by digger wasps.

On Downley Common we heard the first chiffchaff of the season for many of us and had a good view of a male pheasant, but birds were few. It was time 5cm long great green bush cricket (its legs and to return to the café for a well-earned tea. head are central in this picture) Carol Smith Photo: Tony Wright

As we walked amongst the grassland, many bees, Yoesden Bank, A BBOWT Reserve, grasshoppers and crickets were seen and heard. Bledlow Ridge One grasshopper was identified as the conehead. Saturday, 23 June 2018 But the big find was the great green bush cricket, which is England’s largest insect at 5cm long. This was a very lucky find, sadly not seen by all of us, This south-facing steep bank is a typical Chiltern because it is only found at a very few sites in hillside and shows many species of plants that southern England. Fortunately, Tony Wright who specialise on this chalky soil. It is a rare example of had organized this extra outing was amongst the grassland that has never been ploughed, received lucky ones! fertilisers or undergone extensive grazing. It is Carol Smith topped by ‘beech hanger’ woodland. We were interested to see what wildflowers and insects thrived here and we did our best to identify some of these. For once, binoculars were not needed!

Ash dieback If you no longer wish to hear from Typical Chiltern trees included dogwood, Chorleywood & District RSPB Local Group, whitebeam and wayfaring tree. We noticed that please contact our Membership Secretaries, several ash trees had lost leaves on some Chris and Linda Emery, at branches and we thought that they were suffering [email protected] from ash dieback. Several ash saplings, which are in order to unsubscribe from more immediately vulnerable, had died. Older trees communications. Please confirm your name die more slowly. Finding ash dieback here did not and address and state that you wish to surprise us, as the Forestry Commission in their unsubscribe from the Chorleywood Local latest survey (2018), concluded that 64% of all RSPB Group’s communications. 10km squares in England have cases of this new disease and it is known to have reached the Any advertisements enclosed with this Chilterns where ash is a very common tree. newsletter are not specifically endorsed by

the RSPB or the Chorleywood & District Local The brambles were in full flower and hosted many RSPB Group. meadow brown butterflies. Also, we saw a few small tortoiseshells, gatekeepers, red admirals, ringlets and many marbled whites feeding on knapweed and field scabious.

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