A visit to the gardens last Friday in order check out late summer dragonflies and damsel flies, turned out to be one of the best trips for wildlife I have had to this site. Starting out at the fountain we had our first dragonfly species, a single female Southern Darter ovipositing on the pond vegetation, along with a lone Blue-tailed Damselfly.

On the main lake there was plenty of dragonfly activity in the form of Common and Ruddy Darters, Brown Hawkers and hovering Migrant Hawkers. There were also small numbers of Common Blue Damselflies. The main entertainment here however was provided by a pair of Kingfishers who performed a number of flybys over the lake.

On the western edge of the lake we found two Water Voles, one of which was content to feed just a few feet from us allowing great views and photo opportunities.

At about this time last year, I had photographed a pair of mating Willow Emerald Damselflies which was a first for this site and I was hoping to find evidence that they had become established here. We found one male specimen  in the exact location the pair had been seen the previous year, and the following day another observer found five. This along with other sightings suggests this species is now well established in Cambridgeshire.

Other observation of note  were a number of Speckled Wood butterflies, good views of one of the resident Jays and an unknown species of wolf spider walking on water carrying  her bundle of eggs behind her.

Paul Rule

Swifts breeding in our study area have mostly gone – there seemed to be major overnight departures on Tuesday 1st and Saturday 5th August but a few remained over Chesterton until 12th August. Since then occasional birds are probably over-flying migrants moving south but about 10 were feeding with swallows over Midsummer Common on 20th August. Two pairs used the Swift Tower on Logan’s Meadow and at least 10 nest boxes on Edgecombe Flats, near Campkin Road, were occupied. A Chiffchaff, singing in Huntingdon Road on 12th August, was probably a passage bird confused by a spring-like sunny day.

August is wader passage time. Overflying night migrants that often call include Whimbrels, Godwits and Green Sandpipers. On a clear night listen for their contact calls especially if the prevailing winds are from the north or east. An examination of prey from Peregrine Falcons nesting in Nottingham found the remains of night migrants such as Water Rails, Nightjars and waders.

The two pairs of nesting Peregrines in our project area both reared two young. One of the young from the City centre crash landed in Caius College and spent five days R&R at the Raptor Foundation near St Ives. It was then successfully reunited with its parents in the City.

Our project has four new surveys and we are asking for records. One of these surveys is for Tawny Owl records. From August young Tawnies are ejected from parental territories and attempt to set up their own home patch. They can fetch up in any wooded area, including our gardens, especially if near open ground where they can hunt small mammals and earthworms – Tawny Owls are great worm eaters! The “tuwit too- wooo” is an amalgam of the female call – “tuwit” or better a sharp “kerwick” and the male call – “ too-whoo”. There is a breeding pair with well fledged young in Sidgewick Avenue.

Please send Tawny Owl records to nathistcam@gmail.com or to me at the email the address below giving date, location – street name. All records will be confidential and also forwarded to the County Bird Recorder.

Sparrowhawk (left)
© Frank Bell 

Another raptor common in the City is the Sparrow hawk. A male was displaying over Logan’s Meadow Chesterton at the beginning of August – why? Probably, like the Chiffchaff, inspired by a warm day rather than a late nesting attempt. Sparrowhawks were our commonest raptor until 1960 but agricultural pesticide poisoning caused them to become extinct in Cambridgeshire for 25 years until a nesting pair was discovered in a wood in the west of the County in 1985. Since then numbers have recovered and now they are probably as common as they ever were. It is difficult to estimate their current population in our project area but it is possibly 10-15 breeding pairs.

Little Egret on the Snakey Path (left)  © Bob Jarman

Future bird projects in our study area will include, (Grey) Herons, Little Egrets and wintering thrushes: Redwings and Fieldfares. Redwings will be with us very soon – early birds arrive on the coast at the beginning of September. Redwings are frequent night migrants and can be heard passing overhead with a high, drawn out, “seep” contact call.

August 2017

bobjarman99@btinternet.com

Migrants are beginning to slip away. Swifts arrive in early May and depart in August, a shorter visit than most of the summer migrants. A Newnham neighbour has an established swift colony, with both boxes and adapted bricks being used. Behind the bricks are nesting boxes with a glass back, to allow photography and monitoring.  She reports, “We last saw them on August 15th, the adults went in the evening and then the chick fledged sometime in the night … empty box on August 16th. On August 17th I saw a solitary swift swooping round our house briefly, before it flew up and away.”  Swifts have also been using the Swift Tower in Logan’s Meadow, Chesterton since 2011. The main constraint on these birds must be the availability of flies, whose numbers have plummeted over the last 30 years.

Another neighbour recently found a large toad in her garden, also a humming-bird hawk-moth. At the allotments, there has been a superb crop of blackberries, the best for some time. In the local playing fields, cooler nights and lots of rain produced an interesting crop of fungi: a field mushroom, some boletus (Slippery Jack) and some horse mushrooms (larger version of the field mushroom). I did not eat the latter, as there was a suggestion of yellow-tingeing on the broken surface, but enjoyed the others. The boletus is dependent on the adjacent pine trees, which sadly have just been felled, so presumably that will be the end of these at this site.

Relaxing over coffee in the graduate centre, a peregrine falcon came past at eye level – a lovely sight.  One evening, by the river, a kingfisher zipped its way through the swimmers, going upstream.     A lesser stag beetle (with the wonderful Latin name of Dorcus parallelipipedus) turned up on the pavement outside the social club in Newnham. On August 27th, I heard a snatch of chiffchaff song, as well as the contact calls. I wondered if he was calling to gather up comrades for his migration flight.

At Cherry Hinton Hall, workmen were clearing away the remains of the Folk Festival – squares and rings of paler grass indicating the presence of tents over the weekend. Jays called in the woodland and in the lake were yellow patches of marsh marigold.

The spider of the month is this fellow, whom I found in the bath….

Larger than the house spider (Tegenaria domestica), this giant house spider (recently renamed Eratigena atrica but previously T. duellica) is also common and just as harmless.  The female body size can reach 18.5 mm in length, with males slightly smaller at around 12 to 15 mm. The female leg span is typically around 45 mm while the leg span of the male is highly variable, between 25 and 75 mm. This one has enlarged, club-like pedipalps, so is a mature male, with body 13mm and leg span 66mm. He was doubtless looking for a mate when he fell into my bath. (I will leave a towel over the edge, so he can get out unaided next time.) Once mated, he will remain with the female and eventually become her dinner – the ultimate recycling event!

 Olwen Williams

Our local pair of swans have hatched (and so far raised) eight cygnets – they are very attentive parents! Many of the songsters are too busy with offspring to sing much, but song thrush, chiffchaff and blackcap are still about and vocal. Swifts can also be heard (July 20^th) but perhaps for not too much longer, as small groups appear to be heading south. In Paradise, there are reports of 3 egrets, in the company of a heron.  Then, in the river above Newnham, a common tern swooped between the swimmers to pick up a fish.

The dominant colours of the flowers in summer and autumn seem to be purple and red. Tufted vetch keeps company with knapweed, great willow herb, mallow, betony, spear and marsh thistle, bittersweet (woody nightshade) and woundwort. Even the white yarrow has taken on a pink colour in places. Much of the grass is yellow now, but the new growth of nettles more than makes up for this. Many of the nettles in Paradise lack stinging hairs. This is generally true of places where grazing animals have not been present for some time and so the stinging properties are unnecessary. Stinging hairs are costly for the plant to produce, so in this situation, there is selection pressure against them.

Among the nettles was a small (~1 cm) snail – one of the Amber snails – whose aperture is longer than the spire. Although there are two very similar species, I think this one was Succinea putris, which frequents wet places.

Spider of the month has to be the garden spider, Araneus diadematus.  Although most are not yet fully grown, they are actively renewing their webs every morning.

Olwen Williams

Blackcaps are still singing in Logan’s Meadow which suggests a second or even a third breeding attempt this year. In Rustat Road, in an unkempt patch about 3m x 3m at the end of a well-cared for garden, Chiffchaffs were feeding young in mid-July and others still singing in Huntingdon Road gardens. The Willow Warbler on Coldham’s Common with the “chiff chaff” notes at the end of its song was also still singing in mid-July.

Chiffchaffs have out-numbered Willow Warbler by about 10:1 in our project area this year. Apart from the Coldham’s Common bird, the only Willow Warblers I have heard have been along the river opposite Fen Ditton and three singing in the birch thicket near the new Cambridge North Station.

The July issue of British Birds has a paper which suggests Willow Warblers have declined in southern England while populations in the north have remained stable or have increased.

Willow Warbler – above

Blackcap (female) – below

The average shift north of 122 species of British birds is about 20.4 km or 1-km per year or almost 3m per day! (Pearce-Higgins 2017). A good example is the Spotted Flycatcher which used to be regular in our NatHistCam project area but is now a rarity. In Scotland, especially around sheep pastures, it is still common.

The Cambridgeshire Bird Club has a current project on the present distribution of the Spotted Flycatcher – if you have any recent records (from anywhere in Cambs) please let Michael Holdsworth know: spofl@cambridgebirdclub.org.uk.

The reasons for this move north are probably related to climate change and a decline in insects. The BBC’s Farming Today reported that the banned neonicotinamide insecticides, that some believe are responsible for the decline in bee species, are still widely used on non-flowering agricultural crops such as sugar beet, turnips and kale to reduce aphids and the transmission of virus yellows.

Common Tern on Riverside (below)

A pair of Common Terns can still be seen regularly feeding along Riverside often heading down river with food; if you know where they are breeding please let the Cambridgeshire Bird Club know: recorder@cambridgebirdclub.org.uk

Marbled White on Coldham’s Common (left)

Has it been a good year for butterflies? The Marbled White is a species that has increased in recent years and has expanded its range from chalk grassland to grassy corners. This year I have seen them on a farm site in the north of our project area and on Coldham’s Common. There is an excellent book: The Butterflies of Cambridgeshire published by the Cambridgeshire and Essex Butterfly Conservation Branch that is well worth buying!

Field, R. Perrin, V. Bacon, L. Greatorex-Davies, N. (2006) The Butterflies of Cambridgeshire. Butterfly Conservation Cambridgeshire and Essex Branch – ISBN 0-9554347-0-X; 978-0-9554347-0-9
Pierce-Higgins, J.W. 2017. Birds and Climate Change. British Birds 110:388-404.

Bob Jarman 24^th July 2017

In the last 30 years a sub-population of Blackcaps from central Europe have developed a new migration route. Ringing recoveries show that our wintering Blackcaps come from Germany and Austria and have travelled in a WNW direction. The typical migratory route is SW to over-winter in the Iberian Peninsula and Morocco. The belief is that our warming winters and especially garden feeders are the reasons Blackcaps are over-wintering. From January to March 2017 we received Blackcap records from 28 locations in our project area in the City. Twenty-eight locations seemed good and so the records were consolidated into our project.

Male blackcap (right)

Female Blackcap “Browncap” (below)

That changed when I received a letter from Margaret Risbeth on 21st a long-time member of the Cambridgeshire Bird Club. She sent me a detailed log of records of Blackcaps seen in her garden in Hinton Avenue, Cambridge. At the end of her records of Blackcaps in her garden she concluded that:

• The wintering birds left by March 18th – how did she know? Because the winter birds never sang to establish a breeding territory.
• The summer migrants arrived on March 23rd – how did she know? Because the summer arrivals sang to establish territory.
• The summer Blackcaps never use the garden feeders – the wintering birds do.

Bill measurements from captured over-wintering birds show that winter birds have thicker bills than summering birds which may be a micro-adaptation to feeding on seeds and fat balls in garden feeders.

To extend Margaret’s observations further it maybe that Blackcaps are showing evolutionary behaviour with changes in morphology (bill thickening), physiology (ability to digest seeds and fat balls) and behaviour (new migration route). A reasonable comparison would be the evolution of Darwin’s Finches on the Galapagos Islands (incidentally, not discovered by Darwin!).

To extend the analysis even further what we might be seeing is the “micro-evolution”, in the last 30 years, of a new clone or even sub-species. What happens in central Europe, when our wintering population returns and meet Blackcaps that have arrived from their SW migration, could tell us whether a new population is evolving. Wait long enough and birders may get another species tick!

4th July 2017

bobjarman99@btinternet.com

The City centre Peregrines have reared two chicks. One fell onto the pavement below and was rescued. The second chick is fully feathered and now glowers down onto the street below waiting for the parent birds to return with prey.

Below: Juvenile Peregrine photographed on 17^th June 2017

The second city pair has two healthy chicks. At the beginning of June a dead Buzzard was found close to their nest site. At some nest sites Peregrines have been seen to kill Common Buzzards – presumably they see them as a predatory threat. This dead Buzzard appeared uninjured and on close examination turned out to be a Honey Buzzard!

Honey Buzzards are rare breeding birds with about 50 breeding pairs in the UK and very occasional annual passage migrants over the City in the first weeks of May. A June record is exceptional. Could this be one of a pair that is breeding locally?

The Peregrines at this second city site often nest with a pair of Kestrels and Stock Doves nesting closely nearby without any apparent antagonism!

A female Black Redstart has been seen at a central City location – no male has been seen or heard so it’s likely this lone individual is an unpaired female on an early return migration. But its show they maybe about in the City; central Cambridge, around the colleges and churches, is a likely location.

Bob Jarman 19^th June 2017