Category Archives: Project Blog

This blog will record the progress of the project as we go along.

August sightings

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.

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

The Water Vole and the Folk Festival

I was cycling along  Cherryhinton brook one afternoon last week and heard the music from the Folk Festival drifting over the alotments, a nice lilting melody mixing with the sounds of nature all around. As I rounded one of the bends in the footpath I noticed a little water vole sitting mesmerised on a patch of Greater pond sedge (Carex riparia) .  I am sure it was feeling just as mellow as I was. It knew I was watching but went about its nibbling for some moments. Then plunged into the water and dived down to the bottom of the stream. A great cloud of mud billowed up as the vole started an excavation process. It was digging at the base of the sedge plant and eventually resurfaced with a length of white succulent rhizome in its mouth. It then resumed its meal and had soon consumed this prized moursel. I imagine the rhizomes must contain lots of stored starch, so the vole was getting a much better meal than it gets from endless nibbling of the leaves.  It was a very young vole and quite small, so I wonder how it learnt to expertly dive and excavate in this way so early in its life. Presumably by watching its parents.
I have discovered that if you want to see a water vole, the easiest way of spotting them is to look out for unusual ripples on the water surface. The voles sit under the bank and nibble food. The frequency of their nibbling is much faster than other animals, so the ripples they produce are a shorter wave length than say a moorhen or a mallard, which are also found along the brook. I think the ripples come from the vibration of their tummies as they nibble. They are very enthusiastic nibblers and they are always eating. I can often find the hidden voles right in the middle of a sedge bed in this way. You just hang around a while and the vole is sure to appear.

July sightings

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 20th) 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

It’s been a good year for – Warblers

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 24th July 2017

Wintering Blackcap Survey – update 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

Peregrines – update June 2017

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 17th 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 19th June 2017

June sightings

High summer!! A alternating mixture of rain and heat has provided an excellent growing season and some spectacular flowers. In my garden, bumble bees are investigating the honeysuckle and foxglove flowers. In particular, the Common Carder (Bombus pascuorum) and the Garden Bumblebee (B. hortorum) have long tongues and are able to reach into the deeper flowers. I have also seen the Early Bumblebee (B. pratorum) here.

In Paradise, there is a nest of Tree Bumblebees (B. hypnorum), recognised by its combination of ginger thorax, black abdomen and white tail. The nest is in a willow tree about 8 ft off the ground and is patrolled by ardent males, waiting for the virgin queens to emerge. These bumblebees are relative newcomers to UK, having arrived only in 2001 from Continental Europe, but are spreading widely and have reached both Ireland and Scotland.

Tree Bumblebee Bombus hypnorum

In the heat, the river is a popular place to swim. However, there is a warning of the “river itch”, especially on hot days. This is caused by the larvae of a flatworm, whose primary host is a snail. The free-swimming larvae seek their secondary host, a duck, but may mistakenly attack a swimming human. Apart from an irritating rash, the larvae are harmless to us.

There seem to be exceptional numbers of singing Blackcaps and I am also hearing Chiffchaff locally. The Song Thrushes are still vocal and a little pile of broken snail shells indicates where they are feeding.  Skylarks sing over the Grantchester fields, but I have not heard a Yellow Hammer there this year. The local Herons are noisier than ever, now that the young are hatched and courting is overtaken by childcare duties.

In the house, I disturbed a very large House Spider (Tegenaria domestica). I left him there, hoping his diet includes my current plague of Clothes Moths. There seem to be very few flies for him this year. A recent publication* states that there has been a

decline of about 80% in the biomass of insects over the last few decades (since 1989). I wonder why?

Olwen Williams

*http://www.sciencemag.org/news/2017/05/where-have-all-insects-gone?ad_id=2336&utm_source=NHBS+News+%26+Updates&utm_campaign=f239c7a10b-ento_where_have_all_the_inse_06_02_2017&utm_medium=email&utm_term=0_9dd4930fe0-f239c7a10b-58705889&mc_cid=f239c7a10b&mc_eid=5a75c2dd6c

Winter in Mozambique or catching pigeons in the Market Square?

One of our most exciting spring migrants is the Hobby, a swift-shaped falcon. Satellite tagging has shown they spend their winters catching termites in Mozambique. One or two pairs probably breed on the edges of our project area; hunting birds are often over the City and were recently seen over Huntingdon Road and Chesterton. In the early 1960’s this species was confined to the New Forest and Dorset heaths. Slowly, it expanded its range and by 1964 there may have been 1-2 pairs nesting in Cambridgeshire. Until the 1960’s this species was a target for bird nesters. It uses disused crows nests and is faithful to suitable breeding sites; a breeding site in the north of our project area has probably been used for the last 25 years. It nests late and entire clutches were stolen to order. Once taken the birds did not usually lay again and if they did the eggs were often stolen for a second time.

The ban on egg collecting and more importantly enforcing the ban enabled the Hobby to expand from its New Forest strong-hold. Crows were less persecuted so the number of potential nest sites increased. The extraction of gravel in the Home Counties and into Cambridgeshire created open water gravel pits for it to feed on one of its favourite prey items – dragonflies.

While Hobbys are away in winter chasing termites in southern Africa, the City’s Peregrines are catching feral pigeons in the Market Square or wildfowl on the Ouse Washes.

The male Peregrine of our city centre nesting pair on watch some distance from the nest on 15th May – it’s a good sign! The heavy rain the next day on the 16th is a worry as the nest was partially water-logged last year and one chick was lost.

Common Terns have returned and are regularly fishing from Jesus Green to Riverside to Horningsea and Bait’s Bite. Where they breed is a mystery but in August young birds can be seen harassing the adults for food.

The Common Terns below Elizabeth Way Bridge; one of them swallowing a fish about half the size of the bird itself!

There are at least two singing Whitethroats in bushes along the river on Logan’s Meadow. It’s probably our commonest “scrub” warbler; its pleasant short scratchy song is often the prelude to a towering song flight, a rather clumsy hover and then parachute descent into a bush. Nearby are Treecreepers nesting in one of the nest boxes put up by the Council.

 Male Yellow Wagtail                                Whitethroat

Yellow Wagtails are much less common than they used to be. They are birds of meadows and damp pasture. This bird was photographed in a wet puddle near the Histon Rd/Huntingdon Road footpath on the 11th May. They have adapted to agricultural arable crops and occasionally nest in oilseed rape in the north of our project area. A study by Bill Jordan for the Cambridgeshire Bird Club found fenland birds often nested in potato and pea crops.

Male Yellow Wagtails have (probably) the dullest song of all our passerines: “slurp, slurp, slurp” or if you are lucky: “slurp, slurp, slurp, slurp”, but their striking yellow plumage says it all!

So far no definite sight or sound of Black Redstarts in the City.

Couldn’t resist a couple of butterfly pics; a Brimstone, left, on a Primrose and a rather battered Speckled Wood that had probably emerged from hibernation; both taken near Histon Road.

Bob Jarman

17th May 2017

May sightings

The early UK spring foliage and flowers cannot be beaten – returning from a trip to the tropics, I found Cambridge spring in full flood. Elderflower is now adding to the heady scent of the May blossom and cow parsley. Lots of migrant warblers are here now, but it was a great delight to hear a Cuckoo from my back doorstep on May 2nd.

“The cuckoo comes in April,                                                                                           He sings his song in May.                                                                                               In June, he changes his tune                                                                                      And in July he flies away.”

Then on May 10th, the first screams of airborne Swifts, returning for their summer holidays. The UK must be the only place they ever touch down, as they nest and rear young here, but otherwise live their lives on the wing. I expect Bob will tell us where in Cambridge they are nesting.

Mayflies have hatched in Paradise, Newnham’s local nature reserve. The new pond there provides quiet water and lots of emergent vegetation, while excluding large predatory fish. For a few days each spring, evening swarms can be seen as the males search for a female before ending their brief adult lives.

Above the gate and near the chapel in Trinity Great Court, House Martins are busy flying in and out from their nests. By the river in Newnham, a Grey Wagtail investigated the waterside vegetation.

A massive effort was made to clear the invasive Floating Pennywort from the upper river last autumn. At one point, it had spread right across the river. Happily, there is no sign of it at the moment.

My spider of the month is Araneus diadematus.  This well known Garden Spider is generally associated with autumn, but at breakfast on May 18th, I found a newly hatched mass of spiderlings in a communal web.  Yellow and black, there must have been about one hundred of them, clustered together. When disturbed, they fell away on individual threads like golden raindrops and then gradually reassembled. Within a few hours, they had climbed up into the tree and disappeared.

On 31st May, while swimming in the river, I saw a barn owl crossing the river to the Skaters Field nature reserve in Newnham. It was early evening and the owl was moth-like and white in the sunshine. I had been told that they were about, but this was the first time I had seen one.

Olwen Williams

The Unloved 2 – Pigeons and more on Corvids!

What’s the point of Woodpigeons? What do they do? What are they for? The UK breeding population increased by 169% between 1967-2010 (Bird Atlas 2007-11, Balmer et al) probably because of agricultural intensification and boosted by the move to winter oilseed rape and winter cereals from the late 1970’s. The UK population is estimated at 5.4 million pairs and its abundance is probably because of the birds’ ability to survive on green vegetation unlike other granivores (BTO Birdtrends 2014)

More recently Woodpigeons have become dominant garden birds (RSPB Garden Birdwatches) probably as countryside habitats become “full” of resident birds. Despite this their breeding biology and ecology are poorly studied.

        Woodpigeons nesting in
Dorchester town centre

Woodpigeon left;
Collared Dove right

 

A maize stubble field in the north of our study area attracted a flock of 1,480 (counted from photographs) in winter 2015/16. UK birds are almost entirely resident but Woodpigeons in northern Europe do migrate and movements of autumn birds have been noted on the north Norfolk coast. Woodpigeons to birdwatchers are an irritating fact of life! Lone birds can resemble Sparrow Hawks and distant flocks can look like Golden Plovers.

Stock Doves (or Stock Pigeons) are smaller discrete versions of the clattering, bulky Woodpigeon and lack the white wing and white neck patches. They are usually seen singly or in pairs but, unusually, a flock of c100 were feeding on Oil seed Rape stubble from harvest 2016 awaiting spring barley 2017 drilling in the north of our project area.

Feral pigeons: escaped homers, urban vandals, building defacers – these general nuisance birds are thought to derive from wild Rock Doves which are now confined to rocky northern and western cliffs on the very margins of the UK.

These feral birds should now be controlled by urban Peregrines. Cambridge has its own nesting Peregrines (see below); London has 26-30 breeding pairs – the second highest urban Peregrine population in the world behind New York.

Hopefully Peregrines will breed again in the City this year; the female is more strongly barred and bigger than the male by about an additional 1/3rd; they have been seen mating.

Male Peregrine (above)

Female Peregrine (right)

Corvids – the crows – are also unloved (see March blog). The local newspaper in Royston, Hertfordshire is the “Royston Crow” but the crow on the paper’s logo is not the corvid we are familiar with – it’s a Hooded Crow. Hooded Crows used to be considered conspecific with the Carrion Crow but have been granted species status. They used to be frequent winter visitors in flocks of 30+ in Cambridgeshire but are now exceptionally rare – 1 or 2 per year in Norfolk and occasional single strays into the north of Cambs.

Hooded Crows replace Carrion Crows in Ireland and central to northern Scotland and are the common crow in much of Fennoscandinavia and central Europe. Milder winters have probably resulted in these birds remaining resident with little need to move south or west, to the UK, to avoid freezing conditions.

A scruffy Hooded Crow!

The Rook survey in our NatHistCam project area is now 108 (apparently) active nests. Rather like House Sparrows the biggest numbers are in the Cherry Hinton area.

Another corvid is the Jay. This woodland species is a resident and predator of nests and nestlings and eater of slugs and snails. In Chesterton, breeding birds are summer visitors and the first arrived back on March 17th.

May 2017 Bob Jarman