Birds of the Lye Valley: spring 2019

In late March I began regularly visiting Warneford Meadow and Lye Valley to record the birds that I found there. The habitat is described here, but in essence, two small streams pass either side of the Churchill Hospital and form a “Y”-shaped green corridor that adjoins to Southfield Golf Course.

Between late March and late May, a total of 59 species of birds were recorded. This is a decent total for a city site that is not a large waterbody. Of course, not every bird present during this spring will have been recorded. My visits were generally early morning, which tends to reduce the chance of seeing some species, for example soaring raptors who depend on thermals. No scarce migrant passerines were recorded (for example, Wheatear, Redstart, Ring Ouzel) but all are possible.

Red-legged Partridge, Southfield Golf Course

The first surprise came on one of my very first visits when I found a pair of Red-legged Partridge on the golf course very early one morning. There cannot have been many partridge records from Oxford city itself. I heard one calling a few days later, but have not recorded this species since.

In terms of waterbirds, there was only the occasional fly-over Canada Goose flock to add to the local Mallards and Moorhens, both of which bred:

Mallard duckling, one of five on the Boundary Brook balancing pond.
Moorhen chick, on the same pond.

Grey Heron was recorded a couple of times in April, including one bird in the small pools in the Lye Valley:

Grey Heron, Lye Valley

Raptors recorded included Kestrel, which is a local breeder:

Male Kestrel, Boundary Brook valley

There was the occasional Sparrowhawk record, mainly from the golf course area:

Female Sparrowhawk

Red Kites are an abundant species in Oxford and frequently soar over the area. Some birds may roost in the taller trees in the site:

Red Kite, Southfield Golf Course
Red Kite, Lye Valley

On one occasion I disturbed a roosting Buzzard:

Common Buzzard, Boundary Brook valley.

However, raptor of the spring was a fabulous Hobby which flashed over the Golf Course on 18th May, apparently hunting Swifts. Corvid records included Jay, Magpie and Jackdaw, all of whom breed. The exceptional corvid record was a Rook, passing over on 12th April. Hirundines were only represented by two Swallow records: one on 22nd April and one on 2nd May (per Dave Lowe). The first Swift was seen on 18th May, House Martin has yet to be recorded this year!

Great Spotted and Green Woodpeckers are both local breeders:

Female Green Woodpecker

The four common Tit species all breed locally.

Male Great Tit, Warneford Meadow
Adult Long-tailed Tit, Boundary Brook Valley
Juvenile Long-tailed Tit, Warneford Meadow

Coal Tit is the least frequently encountered of the Tit species, but did breed in Boundary Brook valley:

Coal Tit, Boundary Brook Valley
Adult Coal Tit with food.

Five warbler species were recorded this spring (to date). Blackcap was the most abundant, with up to 15 singing males in late April:

Male Blackcap

Chiffchaff was also recorded on every visit, with at least three singing males and one confirmed breeding pair:

Chiffchaff, Boundary Brook Valley

There were only two Willow Warbler records in April, both singing birds that moved through:

Willow Warbler, Boundary Brook valley

I was pleasantly surprised to find a number of Whitethroat territories so deep in the city. The first bird was recorded on 20th April. Up to three singing males set up territories, but have recently stopped singing, so time will tell if they managed to attract a mate and breed:

Whitethroat, Warneford Meadow

The best trans-Saharan migrant recorded in the area was Lesser Whitethroat. A singing male was in a tiny garden in the housing estate behind the Lye Valley on 29th April. Another male was heard on the Golf Course in early May.

Male Lesser Whitethroat

This housing estate has a decent population of House Sparrows and Starlings, by modern standards. They no doubt benefit from the supply of insects and invertebrates in the nature reserve, which has SSSI status.

Male House Sparrow
Starling

The final Siskins were seen on 3rd April…

Male Siskin, Lye Valley

… whilst the first Reed Bunting returned on 7th May:

Male Reed Bunting, Lye Valley

Bird of the spring goes to a bird that I did not see, a Little Egret, photographed by Judy Webb on 9th May in the Lye Valley. I look forward to catching up with this species here, hopefully soon!

Little Egret, Lye Valley © Judy Webb

I used eBird to record my bird records, an illustrated summary of which can be seen here. Anyone (with a free eBird account) can contribute further sightings at the site, now that it is an eBird hotspot. 57 of the species were recorded by myself. Dave Lowe added one further species during his BTO Breeding Bird Survey at the site and Judy Webb contributed the final species, Little Egret.

Other wildlife recorded this spring:

Muntjac Deer were seen on virtually every visit, as were Rabbit and Grey Squirrel. There are signs of Badger too, though I have yet to see any animals. Occasionally I see Red Fox. This adult appeared as I was lining up a picture of the Muntjac behind it:

Male Muntjac and Red Fox, Boundary Brook Valley

I have no expertise of insects or butterflies, plus the early morning nature of my visits means that there is little if any, butterfly activity at dawn. However, some species stand out:

Cardinal Beetle, Boundary Brook Valley
Female Common Blue, Lye Valley
Small Copper, Warneford Meadow

Coming soon: my experience of using eBird and some analysis of the data using bird records from the Lye Valley.

The Lye Valley: a new patch

I have missed not having a local patch. Having spent eight years tramping around the fields of Cuddesdon, I really wanted a good nearby waterbody that would attract a wider selection of species, compared to farmland. I experimented with visiting some well known local sites, for example Farmoor and Otmoor, but found them either too well covered, or too large to cover in my limited avilable time. I also explored smaller water bodies further afield, but quickly realised that I needed a patch that was within walking distance of my house. 

So, over the last three months I have regularly visited a “Y”-shaped piece of land around the nearby Churchill Hospital in Headington, Oxford:

The habitat is varied, but is crammed into East Oxford, between the hospital and housing estates. It does have the advantage of being on top of a hill and has an adjoining golf course, whose open areas I still dream may attract passing migrants. The star of the show is the Lye Valley Nature Reserve. This remarkable piece of wet fenland is centuries old and is home to an incredible range of plants. These survive mainly thanks to the work done by the Friends of Lye Valley and their working parties, led by Dr Judy Webb. 

My usual route begins just off Old Road, Headington. I follow the Boundary Brook stream through the narrow strip of mature trees that survive between the new housing estate of Little Oxford and the University’s Old Road campus. The larger lime trees (I think) have many old woodpecker holes and are home to breeding Jackdaw, Stock Dove and Nuthatch:

As the stream passes the Churchill Hospital, there is a small balancing pond. This holds water draining from the hospital site, before it enters the Boundary Brook. The fantasy here: Water Rail. The reality: Moorhen.

I then do a circuit of Warneford Meadow, [1] on the map above. This open area, right on top of the hill, has scattered trees and nice shrubby hedgerows:

The fantasy here: Redstart. The reality: Meadow Pipit. 

I rejoin the Boundary Brook stream and work my way between the hospital and the golf course [2].  The small valley here is filled with alders:The fantasy here: Mealy Redpoll. The reality: Siskin.

Following this small valley south-east, one emerges on the hospital road to find what looks like the world’s largest mist net [3].  This is in fact a screen to protect the hospital from golf balls being aimed at the 18th green, in the foreground:

The Boundary Brook valley then runs alongside a small meadow at the south end of the hospital [4]: There are reeds on the edge of the meadow, which contains some strange man-made mounds. I have met hospital workers who remember that there were Nissen Huts here, left over from when this was an American base in the Second World War. Frighteningly, some were still used by the hospital for appointments, at least until the 1990s. The fantasy here: Black Redstart. The reality: Robin. 

I then head south, through the woods at the bottom of the Lye Valley and cross Southfield Golf Course [5]. I like the idea of birding the golf course, which is right on top of the ridge, with open grassy areas and scrubby patches. But there are a number of issues. Firstly, there is the possibility of being hit by golf balls:

Secondly, you may be suddenly doused by the watering system on the greens. Without warning sprinklers are turned on, which does not always make for relaxed birding: The fantasy here: Hoopoe. The reality: Pheasant. 

The furthest south I get is the scrub on the slope of the hill between the golf course and the Barracks Lane cycle track: The fantasy here: Nightingale. The reality: Blackcap. I do a circuit here, then retrace my steps back over the golf course to return to the Lye Valley proper [6]: Emerging from the woods, one finds small pools by the boardwalk at the bottom of the fen. From the top of the reserve [7] the stirling work done by volunteers to keep the fen free from encroachment by trees and shrubs can be seen: 

This spring I have really enjoyed my early morning birding in these narrow green corridors, between the hospital, the golf course and the houses. Coming soon: a summary of the birds seen here this spring: March, April and May 2019.

Bird of the Month: Northern Wheatear

This is an article I wrote for the Cumnor Village Magazine for their April 2019 edition:

A walk around the fields surrounding Cumnor this month could easily produce a sighting of one of the most remarkable migrant birds on earth: the Northern Wheatear. Wheatears are ground loving birds. They feed on insects and invertebrates found in short grass in exposed fields and meadows. They are attractive birds. Spring males have a black mask and a blue-grey back. But whilst most often seen on the ground they are most easily detected when they fly. Their lower back, just above the black tail, is pure white. When a Wheatear flies, the flash of white is very obvious.

Wheatears do not breed in Oxfordshire. The birds we see in the fields around Cumnor are pausing on their migration between their wintering grounds and their breeding grounds. The story of Wheatear migration is quite incredible. Every Wheatear on earth spends its winter in Africa, on the vast dry plains just south of the Sahara. This is their ancestral home. Their winter range stretches in a wide band across central Africa, from Mauritania in the west across to Sudan in the east.

Every spring, Northern Wheatears leave their wintering grounds and fly north in their millions. But unlike the Swallows, House Martins and warblers that migrate with them, most Wheatears do not finish their journey in England. In fact, for some birds their journey has only just begun. Some populations of Northern Wheatears continue across the UK and fly directly to Greenland and north-east Canada. Recent research has shown that these birds undertake a sea crossing of over 3,000km (1,500 miles) in a single flight. Quite an achievement for a bird that only weighs as much as four ten pence pieces.

Every autumn these Northern Wheaters repeat their epic journey and fly from Canada and Greenland, back to central Africa. They are one of very few bird species that breed in the new world, but winter in the old world. These populations are known as “Greenland Wheatears”. They have longer wings than the birds that breed in Europe, reflecting their much longer migrations. Greenland Wheatears are more richly coloured than European Northern Wheatears, often having rich, apricot-coloured underparts:

Probable Greenland Wheatear, Cuddesdon, April 2011

But Greenland Wheaters are not the most travelled Wheatears. The incredible migration of Greenland Wheatears from Africa, into Europe and then out across the Atlantic is dwarfed by the distances covered by their eastern cousins. Northern Wheatears that winter in east Africa breed right across northern Russia, and have even spread into Alaska. A single spring migration for these birds involves flying across Asia for some 15,000km (9,000 miles). They then raise young and depart the short northern summer for their African homeland, crossing half the world in order to do so.

The Northern Wheatears we see in Oxfordshire in autumn are a different colour to the birds seen in spring. They replace their breeding finery with their winter plumage, one suited to the dry brown shades of the plains of Africa:

Nothern Wheatear, Cuddesdon, August 2013

If you are out walking this month and flush a bird from the ground which shows a clean white rump as it flies, then you have probably found a Northern Wheatear. These birds like a view and often perch on rocks, mounds of earth or even hedgerows. Make the most of your views of them. For those very same birds could be in Greenland or Canada within days, having completed one of the most incredible flights of migration.

Northern Wheatear, Lundy Island, October 2010. 

Oxford Ornithological Society AGM and talk

I was honoured to be invited to talk at the AGM of the Oxford Ornithological Society last Wednesday, 8th May.  I recounted my experiences of birding the Oxfordshire green belt to a turn-out of over 50 members. Inevitably this also involved looking at the massive declines in farmland birds in the last 30 years and the role of intensive agriculture in these declines. But I tried to throw in a few jokes as well. Dr Alan Larkman, OOS Chairperson, then gave an excellent presentation about the valuable conservation efforts taking place on City Farm, near Eynsham. It was great to see some familiar, and some new, faces and to receive some positive feedback too. Special thanks to comrades Badger and Mark for their support.

It was also a pleasant surprise to come across this blog post from OOS secretary Barry Hudson the following morning. Thanks Barry!

A day on the Farnes

I spent Saturday on the Farne Islands with a friend and his father, who was visiting the UK from abroad. They had asked to see some UK birdlife and I reasoned that our breeding seabirds are one of this country’s most spectacular wildlife sights. Although cold overnight (3 degrees in May!), the cloud quickly dispersed and for most of the day we had sunshine and blue skies – which also means blue seas in our photographs, a real bonus.  

We travelled up to Northumberland on Friday, to a small town at the foot of the Cheviot Hills. I was delighted to find a breeding pair of Dipper under a bridge close to our house. Dawn on Saturday found us by the river, watching the comings and goings of thse fabulous birds:

Then, after breakfast, we drove to Seahouses to catch the boat to the Farne Islands.

Immediately there were birds and wildlife. This smart drake Eider was one of a small number in the harbour:

As we left the harbour, a series of distant splashes drew our attention to a distant pod of Bottlenose Dolphin in the bay:

As we approached the Farnes, the sheer number of seabirds around the islands became apparent:

There were vast numbers of Guillemots, smaller numbers of Puffins and Razorbills, with Kittiwakes circling above and Shags jump-diving for fish. A few of the Guillemots were of the bridled form, with smart white eyewear:

But it was always the Puffins that caught the eye. Seeing these birds close on the water in sunshine was a real treat:

We landed on Staple Island, where one can walk just a few meters from thousands of breeding seabirds. Shags were nest building and incubating all around us:

Razorbills were breeding too, but not in the same vast numbers as the Guillemots:

I have visited the Farnes before, in July 2011. It was fascinating to see the different behaviour of the birds at this time of  year, at a much earlier date in the breeding season. There were no birds bringing in fish, as no young had been hatched yet. Instead the Puffins were in courtship and burrow-claiming mode. Some birds had obviously been underground recently:

Whilst others ran around with beaks full of nesting material:

We saw a wide variety of social interactions between the Puffins. The bird below was actively defending a burrow entrance. Bill-gaping is antagonistic behaviour, revealing the birds bright yellow gape and tongue:

The left-hand bird of this pair approached the right-hand bird with a low-profile-walking display, before they began bowing to each other:

Then it was time for some portraits:

Getting flight pictures of Puffin takes some time, they are fast fliers. I eventually found a spot where I could look down on approaching Puffins, where the light was good and the sea appeared blue:

We left Staple Island at lunchtime and took the boat to Inner Farne.

This larger island has the breeding auks of Staple Island, but also many breeding terns, including Arctic, Common and Sandwhich Terns.  The Arctic Terns here are ridiculously tame:

This early in the season we saw little aggressive behaviour from the the Arctic Terns. In July one needed head protection to avoid birds diving at visitors on the walkways. 

The cliffs also held breeding Guillemots, plus a small number of bridled birds, my favourite form:

But even on Inner Farne, Puffins were everywhere. The numbers were astounding. They sat on open grassy areas, on buildings, on walls…

… even flying directly overhead:

The day finished, as it had begun, with a nice drake Eider:

We left the Arctic Terns and breeding seabirds and sailed back to Seahouses:

Visiting the Farne Islands in the breeding season is an almost overwhelming experience. The sheer number of breeding birds is a powerful assult on one’s senses, both sight and smell! But being surrounded by thousands of Puffins makes the day a very special encounter.

Emperors emerging

Great excitement yesterday as our first Emperor Moth emerged. They are stunning moths, quite large, with obvious “eye” patches on both fore and hindwings, above and below. This fabulous female was one of a batch we raised on Hawthorn last summer:

Emperor Moths, from egg to cocoon in 6 weeks

Detail of the eye pattern on the upper forewing:

Even from below, the “eyes” on the wings are visible. These presumably act as a deterrent, confusing potential predators into thinking that they are looking into the face of a much larger animal:

We transferred our Empress to a hawthorn bush across the road, one of the Emperor Moth’s host plants. It was the same bush that we fed the caterpillars from last summer.  We left her there and thought that was it.

This afternoon, my wife took our children and some friends across the road to see if the female Emperor had moved. She had not. But even better, she had attracted not one, but two, males:

Male Emperor Moths are smaller and more reddish than the large silver females. One male had succeeded in attaching his abdomen to the female. This was a rather worn individual, with evidence of some wing damage in comparison with the completely pristine, freshly emerged female:

The male Emperors had located our female purely by scent. Their antennae are finely tuned to the pheromones that the female emits from her abdomen. I wrote about the wonder and sensitivity of moth antennae in this recent post:

The wonder of antennae

In over two years of regular moth trapping in Headington we have never caught an Emperor Moth. This was no great surprise, they are not easily attracted to light. Instead, the males spend their time seeking out females, tracking them down efficiently by following their pheromone trail. In less than 24 hours, our female had attracted two males, demonstrating the species is present in our local area. The male’s antennae are clearly visible here:

Below, underwing details. The clasping mechanism at the end of the abdomen is visible. Each species of moth has evolved only to interlock with females of the same species. 

Below upperwing detail of the, slightly tatty, male Emperor:

A fantastic afternoon, with excitement for adults and children alike, present in the company of the Emperors. 

Blenheim Bonaparte’s

Bonaparte’s Gulls don’t create the stir they once did. The bird at Farmoor in mid-May 2000 was a major event. Since then there have been another four, all in spring, with birds being found on 18th April 2006; 1st May 2007; 11th April 2009; 8th April 2017. The bird found yesterday by Nic Hallam (who has found most of the county records) is the 6th for the county, by my reckoning. 

I had two children in tow when I arrived at Blenheim Palace this afternoon. Badger and two other birders were already watching it dip-feed at the back of the main lake. It was distant and the light was terrible. The Bonaparte’s Gull could be picked out from the many Black-headed Gulls just because it looked so clean and bright, an impression created by the pale inner primaries on the underwing. 

I  needed to tempt it closer. Feeling determined, I took my children up back into the main house and into the cafe. I didn’t buy them anything, but instead found myself wondering what the Bonaparte’s Gull would prefer: scones or sausage rolls? Despite the fact my wife does not eat pork and that a well known vegan Oxonbirder was looking after my ‘scope by the lakeside, I went for the meat. It worked a treat.

Black-headed Gulls noticed me tossing food into the air and came over to investigate. The Bonaparte’s came with them. It’s dark head – not really black, but darker than the accompanying Black-headed Gulls – was not quite complete: 

The leg colour was visible at quite some distance:

I even had the satisfaction of seeing the Bonaparte’s Gull, take a piece of my sausage roll:

Although this made it a target for other gulls…

…causing the Bonaparte’s Gull to react furiously:

Within a couple of minutes the food was gone and all the gulls returned to patrolling the far side of the lake. I took my children back to the cafe, to reward them for their patience, and we spent the rest of the afternoon enjoying the sunshine at Blenheim. Easy birding. 

 

The wonder of antennae

I am participating in the Garden Moth Scheme this year, so put out the moth trap in our garden every Friday evening and record our catch. This Friday saw a large increase in the number of moths and our first Oak Beauty:

The antennae on this moth are fabulous, especially the white dots running  along the shaft of the upper surface of the antennae:

This got me wondering.  Why do some moths have complex antennae, but most do not? Most moths have simple antennae. I was immediately encouraged to look into this. Partly because I have enjoyed photographing the amazing variations of antennae in our moth trap, but also because I have discovered that time stops when you start looking closely at moths. 

A number of different antennae shapes have been recorded in moths (image © here):

The majority of moths have simple antennae, like the Buff-tip, Poplar Hawk Moth and Brimstone Moths, below:

Others have fantastic pectinate or bi-pectinate antennae arrangements, resulting in some truly fabulous headgear. Below, Dark Arches, male Muslin Moth and Pale Prominent: 

Antennae have that evolved over time to perform a wide range of complex functions. These not only include detecting members of the opposite sex through picking up traces of their pheromones, but antennae also have a role to play in providing flight stability. However, in evolutionary terms, antennae began their life as something much more simple: once they were legs. 

The trochanter on the image above of an insect leg (© here), is at the junction between the body and the leg. In antennae this area has specialised to contain two wonderfully named organs: the Johnston’s Organ and the Böhm’s Bristles: 

Johnston’s Organ (in the pedicle or second section of the antennae) detects motion in flagellum (the third and final section of the antennae) and helps provide flight stability. It is tuned to detect angular changes during maneuvering in complex flight, as demonstrated in Hawkmoths here. 

Böhm’s Bristles appear to help control position of the antennae during flight. They are found at the base of the antenna and are tiny, but are visible in these images, labelled “BB” (© here):

The discovery that antennae help provide flight stability in moths is relatively new. Moth antennae are best known as organs of smell. They are highly specialised olfactory organs and can be incredibly sensitive. Amazingly, Indian Lunar Moths have been shown to be able detect a single sex pheromone molecule at a distance of 11km (6.5 miles), see here.

But if that is the case, then why do the majority of moths have simple filamentous antennae and only a minority a more complex array of antennae, like this Brindled Beauty, below?

Surely it would be an advantage to have the largest, most sensitive antennae possible? It appears that this would be the case, but there is a price to pay for having a huge array of pheromone detectors on your head. That price is flight efficiency. Complex bi-pectinate antennae are found on larger moths. Smaller, lighter moths cannot carry around complex antennae without compromising their flight efficiency. Larger moths are less abundant than smaller moths. This is why most moth species have simple filamentous antennae. 

Digging deeper, it appears that even simple filamentous antennae have adapted to improve the efficiency of sex hormone detection. Simple filamentous antennae are covered in scales, which have a function in the detection of pheromones:

This paper found that the presence of these scales increased the amount of nanoparticles (like pheromones) around the antenna, and even filtered out microparticles (like dust), which further increased the efficiency of the antenna. In this way the simple filamentous antennae of smaller moths have become increasingly sensitive at detecting pheromones, without compromising flight efficiency.  

The greater the detail you discover about the natural world, the greater the wonder it generates. The fact that complex pectinate arrays can make antennae look like giant ears is pretty cool too:Pale Tussock 

Out, at last.

It has not been an easy couple of months. In early February I sustained a stress fracture to my hip during a long run. Very quickly I was unable to walk or even weight bear. X-ray and MRI scans confirmed the diagnosis and I spent the next four week on crutches, unable to work. Fortunately the small crack in my femur, just below the ball and socket joint of my hip, did not need surgery and I should make a full recovery. But I was trapped inside for most of February and March. To stave off madness I caught up with lots of computer based work, including writing a few bird related contributions to the Cumnor village magazine:

By Monday morning, I was able to attempt a slow limp around some parts of Dix Pit. It is not reasonable to expect to find something good on your first trip out in 2 months, although an early migrant of some sort would have been nice. Today, just being out in the sunshine was enough. A Water Rail called, Chiffchaffs were singing…

… and the first Peacock butterflies were feeding on the blackthorn flowers. All had a little more meaning, after my period of incarceration. 

My eBird list of species seen is here.

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