Tuesday, 29 October 2019

Mind the gap

To the west of Box Hill you will find a narrow river valley, formed tens of thousands of years ago by the River Mole. It must have once been a mighty river, not the shallow, sluggish water course that it is today. In recent posts you will find maps of the Box Hill area with identified flight lines of migrating birds. I have marked such flight lines along the Mole Gap, but in recent weeks the birds had not been using them - until today.

I arrived at my favoured Box Hill vantage point at 06.30 hrs. It is a small area of flat ground on the scarp slope with views eastwards and, most crucially today, westwards, across the Mole Gap and on towards Ranmore. Thrushes were on the move quickly afterwards, a mixture of Redwings and Fieldfares. After approximately 75 minutes I had recorded at least a thousand of both species. By 09.00hrs the Fieldfares had tailed off, with the stream of Redwings more or less coming to a halt by 10.30hrs. An hour later I called it a day. The final totals were: 4068 Redwing and 1658 Fieldfare.

Almost all of these thrushes arrived from the east, seemingly following the line of the river. About half of them cut across the summit of Box Hill behind me and over into the gap where they headed northwards, continuing to follow the river that changes course just west of Box Hill. The other half continued parallel with the scarp before turning right (and north) up the gap, joining those birds that had taken a short-cut. Had I been sitting west of the gap at Denbigh’s or Ranmore I would have seen none of them. No thrushes appeared to enter the gap from the west. I missed a lot of birds. I was aware of high flocks and distant flocks as I was counting others. Another observer would have been helpful. I would love to have known how much of this would have been seen four miles to the east at Colley Hill. We need an army of sentinel birders placed along the counties high ground...

Today's flight lines

Monday, 21 October 2019

Thrush-bearing cloud

When I stepped out of the house at 07.00hrs the air was laden with moisture. The weather forecast was that of a nagging band of rain stretched across the south-east of England, and unlikely to clear until the afternoon - but it's proposed edge was tantalisingly close to Dorking (according to one satellite image that I had looked at.) So, instead of heading to Colley Hill as intended, I made my way to Box Hill, hoping that the extra few miles west might make a difference in the weather.

Arriving at Box Hill made clear that it hadn't. The roads were awash with standing water, although the headlights did pick out a few Song Thrushes having a bathe. The hill top was shrouded in mist, but walking a third of the way down the scarp allowed some semblance of visibility across Dorking and on towards the Greensand Ridge. Looking south-east I could also just about see aircraft taking off and landing at Gatwick Airport, so I was ready for action. The only problem was the persistence in the drizzle, enough to be a nuisance. This was solved by finding an isolated Yew tree on the slope which I commandeered as an umbrella - this spot gave surprisingly good views from east all the way round to south-west.

The first hour chugged along with a modest number of Redwings and Chaffinches, enlivened by a few Fieldfare and single Siskin and Brambling. With little changing in the weather it was a bit of a surprise to be suddenly hit by some large thrush flocks, mostly following the scarp-line but some coming along the River Mole. The low cloud had kept them to the south of the scarp, as the higher ground was hidden from view. This allowed me excellent observation, as many of them passed directly over my head. Until 10.30hrs these two streams kept going, with Redwings outnumbering Fieldfares three to one. Flocks were generally pure of species, although the odd mixed flock did pass south-westwards. Most of the thrushes moving were in sizeable flocks, 25-75 the average size, the largest being 250.

As the drizzle abated I ventured down the slope and further to the west by 100m. And it was here that I found what I believe to be the best spot on the hill to observe visible migration. I had a good view along the scarp (both east and west), along the river and across the mouth of the Mole Gap. I was able to watch thrushes arrive from all of these directions. At this point, no doubt due to the cloud lifting a bit, a number of birds started to appear high above the mouth of the gap, having, I assumed, arrived along the crest of the downs from the east (I would have been hidden from these birds when I was standing underneath the Yew, but as the cloud was so low then I doubt that I missed any.) A number of flocks started to pitch down at this junction, landing in a small area of Yew and Beech. All 500 or so left together after only a few minutes rest, flying out over the gap, circling high. I watched them split up, with half of them crossing to the Denbigh's scarp, the others bearing west to north-west (Norbury Park area). Very few birds called all morning.

By 11.45hrs it seemed to stop, with a short burst again at 12.15hrs. An hour later I packed up myself.

There was one highlight just before I left though. I picked up a flock of eight Ring Ouzel flying along the scarp underneath me, their long-winged sleek shapes at once alerting me. All seemed to be young birds or adult females, not an adult male among them.

Final totals of the big two movers were 2760 Redwing and 804 Fieldfare. Mostly south-west.

Flight-lines today: Orange (Mole Gap), Yellow (scarp), Purple (river). Optimum viewpoint marked by green circle

Sunday, 20 October 2019

Marsh Harrier topping

Colley Hill can be found on the North Downs just west of Reigate. It is quite a spectacular site, with a steep scarp slope that has, along its length, a couple of natural bowls. These are not accessible to most people, so the partially scrubby slopes remain largely undisturbed. I have a longstanding affection for the place, but my birding victories here have been quite meagre, even though my effort has been reasonable over the years - a Ring Ouzel here and a Common Redstart there is not quite reward enough! To the north (and just over the M25, that bisects the area like some poisoned serpent) you will find open farm and grassland close to the village of Mogador.

Both of these places have been lumped together as a single site for the purposes of recording any visible migration on Trektellen. This morning I took up position at 'Watchpoint 2' (map above) that has a good uninterrupted view northwards across the farmland. It was very misty to start with, but after an hour the visibility improved and so did the birds. A steady trickle of Chaffinches were heading south-west (yellow line on map), with larger numbers of Wood Pigeons south (pink line). There was a broader front of movement than an adherence to these specific lines. There were jewels to be mined amongst the modest supporting cast, with a Ring Ouzel (which left the cover of a hawthorn bush with four Song Thrushes and left westwards) and a calling Golden Plover (not seen as it went south-westwards in the gloom.) I decided to try out the scarp slope itself, taking up position just underneath the top of the hill, looking westwards along the downs (Watchpoint 1, pic below)

It soon became apparent that there were more Chaffinches to be seen from here, with flocks (the largest was 70) taking flight lines parallel with the scarp (green arrow on map). Some of the lines were just above the hilltop, others further out southwards but still at hilltop height. The Woodpigeons continued to move as well, coming off the scarp and heading out south or south westwards. The undoubted highlight occurred at 10.55hrs, when a juvenile Marsh Harrier appeared from the north, over the rim of the hill, and continued southwards out across the Surrey countryside.

Final totals were: Marsh Harrier (1 juv), Red Kite (1), Common Buzzard (8), Sparrowhawk (1), Kestrel (1), Golden Plover (1), Stock Dove (26), Woodpigeon (1,152), House Martin (1), Skylark (1), Meadow Pipit (20), Alba Wagtail (7), Mistle Thrush (2), Ring Ouzel (1), Redwing (18), Song Thrush (8), Starling (61), Chaffinch (424), Goldfinch (8), Linnet (1), Greenfinch (3), Yellowhammer (1)

Thursday, 17 October 2019

Box Hill flight lines

I knew I wouldn't be away too long...

We are at the height of the visible migration season, or vis-mig if you prefer. Ed Stubbs, over at Thorncombe Street, is having a storming time this week and, apart from basking in the glory of finding a Red-throated Pipit, has written a bit about the recent history of this form of skywatching in Surrey. You can read it here.

I have been having a far more modest time, but enjoyable all the same. This morning I went over to Box Hill, and stood on the slopes between 07.15 - 10.45 hrs. My reward was a steady, if unspectacular watch, with Woodpigeons on the move (1,927 south-west), my first three Brambling of the autumn, and back-up from an assortment of thrushes, finches, Starlings, and buntings. It was time well spent. What was educational were the flight-lines that the birds took. They are crudely marked out, in yellow, above.

Firstly were the birds that flew from the north and headed south / south-west over and away from the scarp. These kept to the eastern side of Box Hill, and were viewable from the Scarp Viewpoint. If standing at the Mole Gap viewpoint, these birds would be missed.

Secondly there were birds cruising along the line of the scarp itself. These were at various heights. Again, standing at the Mole Gap viewpoint, these would be missed.

Thirdly, a small number of birds were following the line of the River Mole (mainly thrushes today) and are a bit too distant to identify if they are small passerines. Again, the Mole Gap viewpoint misses these.

So, I hear you ask, why bother with the Mole Gap viewpoint at all. Well, fourthly, there are a number of birds that use the back valley's and some of these head across the mouth of the Mole Gap, clipping the western side of Box Hill. I have had successful sky watches in these valleys, one of which you can relive here. From this viewpoint you can also keep an eye on any bird flying down the gap itself (in the picture above this is handily marked out by the road on the extreme left hand side). The river vaguely follows this road before turning sharply east, just south of Box Hill. Today little seemed to be coming down from the north and through the gap.

There is no one spot that you can take up on Box Hill that allows a 360 degree vantage point, mostly not helped by a heavily wooded crown. However, the Scarp Viewpoint is, without doubt, the best one. It also has a view across the mouth of the Mole Gap, so if birds are seen to be pouring through a quick change of viewpoints can be made. Of course, all this is weather dependent. Where the birds are coming from, and going to, at what height, and whether they can be heard calling will all alter what the observer can identify...

From Box Hill at dawn, looking out towards a misty Betchworth and Leigh

Friday, 11 October 2019

Blog end?

“And now, the end is near...”

Well, as far as blogging is concerned, it certainly feels like it. As a platform it is certainly ‘old school’ and I get the impression that few people under the age of 40 writes one. The blogs that I follow - almost entirely Natural History themed blogs - are showing signs of having become infected by a general blogging malaise - fewer posts, shorter posts, a big fall in interaction with visitors. I’ve got the symptoms too. My posting exhibits a certain tiredness, not as frequent, lacks imagination, fewer comments being left and fewer visitors. This isn’t a whine, they are just the facts.

Is this down to the way our social media functions, in that platforms become passé, attention spans demand short tweets and not wordy lumps of copy? Is it too much effort for visitors to leave a comment, or are the posts not engaging enough? Of course, it could be that if a blogger is dishing up dull material then visitor numbers will fall, as will the number of comments that are left behind. I know that the accumulation of comments is not to be taken as a barometer as to the health of a blog, but their presence certainly points towards an involving one.

Even those blogs that are still producing thought-provoking prose and inspiring material seem to be talking to an empty cyberspace. I even find myself not going to my favourite writers as often, or as keenly, as I used to. Maybe time is up after all?

I still cannot bring myself to pull the plug. There are times when I know that I will post something, and that will galvanise somebody to go out into the field to seek whatever it was that I had written about. If that happens - even just the once - each year, then it was worth it. I used to write opinion pieces, satirical asides and loads of nonsense to pad out the space between my observation derived writing. That spark has left. Either that, or I’ve finally grown up.

The answer might be to send ND&B off on a sabbatical, to get its oomph back.

Wednesday, 2 October 2019

Trektellen time

Trektellen, the website that collates migration counts, is a wonderful place to while away a few hours.  This Dutch site has spread its wings across Europe, and the number of contributing sites - including British - keeps on growing. As much as most of us think of meaningful visible migration counts coming from coastal sites, there are a number of inland sites that have provided some excellent data. As a county, Surrey is poorly represented. I thought it about time to increase its contribution.

Anybody who has visited this blog on a regular basis will know that I love watching migration in action, particularly if it is local to me here in Banstead. It just means more. Luckily I have two sites on my doorstep (one of them literally) that provides such thrills. My garden has a good track record in the autumn - thrush rushes (4,000 Redwings in a day), four figure hirundine days, hundreds of finches, pipits, the odd unexpected bird (Woodlark, Golden Plover, Honey Buzzard, Hawfinch) - and by October I can expect a daily dose of this kind of stuff. The other site is Canons Farm, maybe a mile and a bit to the north of the garden, where I have experienced similar hirundine and thrush days, plus witnessed a spectacular hard weather movement.

So, I contacted Clive McKay, one of Trektellen’s team of administrators, and asked him to set up these two sites on their database. He suggested that, because they are so close, it might be better to merge them under one - called Banstead - and when entering my data make reference to which watchpoint I was present at. Job done! The first entry has now been made.

They might not be Dungeness, nor Spurn, but believe me, it sometimes feels like they are.

Tuesday, 1 October 2019

Where to stand?

I love migration. Birds, butterflies or moths, the privilege of being able to observe it happening is never lost on me. Every session out in the field that coincides with a movement of birds overhead is a treasured session. We are now in the middle of the best time to witness such movements. So, pick your site, go and stand there, look up, and count the birds. Simple. Well, to a point it’s simple, but finding somewhere to stand where you have a good chance of seeing numbers of birds flying through - that isn’t as easy as it might seem.

Anywhere can turn up a good bird. Anywhere can provide you with a bit of visible migration. But those sites that regularly host such avian spectacles are fewer. Logic suggests hills and river valleys are the likeliest spots, but even they can be hit or miss. My own search for a North Downs hot spot, on the scarp slope, has been one of failure. Reigate Hill, Colley Hill, Box Hill and Denbigh’s Hillside have all been given the once, twice and thrice-over with mixed results. My birding colleagues at Leith Hill (Greensand Ridge) and Thorncombe have much better results, and Wes out on the flats at Capel does very well too. So, do the birds not fly ‘along’ the North Downs but pass over on a broad front? What about the Mole Gap? Do they not funnel through there? I have also sat at the break in the hills where the river flows through but to little reward.

My best local visible migration sites are seven miles further north, on a spur of high land. One is Canons Farm, the other my back garden. Both have provided memorable watches with thousands of hirundines, Redwings and finches. In fact, our Banstead garden was as good as anywhere for me last autumn, even throwing up the odd surprise.

But... even if you finally do identify and adopt a site - and the weather conditions are good for bird movement - you can miss out by being a mile or two to the east or west. This past week has seen heavy House Martin and Meadow Pipit movement. I have had my eyes to the sky as often as I could. Sometimes the birds have flowed through. At other times I have seen little whereas an observer not four miles away has been filling his boots. This has been played out across the county, birders rejoicing while others bemoaning their lot. Localised movement has been the way it’s panned out this autumn, very little on a broad front. Another aspect of birding that keeps us guessing. It could be down to the position of a rain band; direction and strength of wind; or even the direction that you are looking in!