Thursday, 30 November 2017

Posting on the fly #1; Funton and the rules/regulations

Funton messes. Just over two months ago the paint pots arrived.




So why are they still there?

Stuff from the lay-by gets cleared almost as soon as someone reports it.Why not stuff on the saltings?


And why does rubbish in the mud tend to stay in the mud?


The Queen's highway

Fly-tipping on highways gets cleared by the local authorities. They have responsibilities for highways. Now you and I might think we know what a highway is, but our understanding often falls way short. A highway is more than a road; a footpath is a highway. Any"way over which all members of the public have the right to pass and repass without hindrance" is also a highway. Unadopted lay-bys, where vehicles have been driven over for years without hindrance, where the owner has allowed the behaviour, can then become part of the highways system. On a narrow road such as Raspberry Hill Lane, such unadopted lay-bys are a godsend on workdays when lorries take the rat-run. So, even though the freehold deeds might say the ownership is with X, sadly X cannot fence off and return to nature (one conservation site I was involved with some years back wanted to do just that when they purchased a parcel of land- soon put straight).

This is why large-scale tipping in the lay-bys along the lane get cleared. The Council have a good response rate, and will prosecute.


Beyond the highway?
Put simply, the freeholder has responsibility. The freeholders all along both sides of that road are painfully aware. Speak to the farmers. They'll tell you they'd love to just move the cak three metres back onto the Highway, but they can't- because they'd then be the ones who are fly-tipping. And the saltings are in private ownership.

If you study the rubbish, you'll soon see new stuff arrives every week. Several of the landowners will pick up general rubbish straight away- that's easy to deal with. More specialist stuff? Sometimes that'll hang around longer, for a full lorryload (more cost effective, especially where disposal is highly technical; white goods, tyres). Unless you look carefully, you may not see the turnover. Some of the paint pots have gone since September.

There's a lot more to it, of course, and there are lots more details here:
Government guidelines
Local Authority responsibilities
Flytipping association




At least the really bad old days of Funton are long behind us. Cars like this one get picked up pretty quickly.


Back in the good ol' days? Long-term parking was the norm. (From 'The Thames transformed', Harrison and Grant, 1976)


Do as I do; pick some of it up to help (and check for addresses!). Think of it as a one minute beach clean. Without the beach. Taking rubbish off the saltings themselves is another matter; the signs make sure we have been informed we do not have permission to leave the lay-bys (though some local birders do sadly still choose to do so). No need; if you walk between lay-bys there's always enough rubbish in the bushes to fill a carrier or two.

Thursday, 23 November 2017

The Gillingham Marshes Ringed Plover roost

Just west of the Strand is Gillingham Cruising Club, many years ago protected its short approach with a series of sunk barges. At low tide they deserve little attention (unless one of the local Grey Wagtails calls), but on some high tides they provide a useful roost.



Any birds using the barges tend to gather on the outer line, which is easily viewable by 'scope from the shore by the Strand golf course, just east of the Club yard on Owens Way, or from the Waterside green. Fairmile wharf is a little further east, but does give better views of approach lines.



It is one of the larger Ringed Plover roosts on the southern shore, often three figures during the winter months. Today on the rising tide 115 had gathered along the easternmost saltings of Gillingham marshes. As the tide continued to flow the birds followed others to a tight pre-roost on the western edge of the barges, before moving onto the roost itself.



While some spread themselves on the outermost barges, the bulk move to the three central wrecks.






In the UK, the bulk of the overwintering Ringed Plover population is found on non-esturine coasts. Populations on these shores have shown a decline since the mid-eighties, so it follows drops in less favoured habitats should be expected, but this is yet another wader species which has suffered from under-recording on the Medway in recent decades. The dramatic downturn for counts for the whole of the estuary came in the mid-nineties, and WeBS results since the time I returned (2012) have continued to infer much smaller numbers. Today, numbers on the Gillingham roost had increased from that 115 to 152 birds on the barges by the time I left, two hours before high tide, with another 20 seen flying in as I walked by Fairmile, higher than the WeBS estuary total in many recent years. There are other small regular roosts along the southern shore; a handful at Sharps Green, slightly more off of Rainham Docks, at Twinney and above Shoregate, plus Bedlams. Adding in the islands and the northern shore, the Medway wintering figures are clearly not being reflected in WeBS.



One of the reasons is most roosts are not occupied seven days a week. The Gillingham Marshes roost was busy today as there was no-one working in the boatyard. Weekends, when most WeBS counts take place, have the greatest amount of activity and the birds often move off at some point during the flow tide. Birds similarly get moved from those other roosts closest to the shoreline footpaths.

Other species which routinely use the barges are Turnstone, Lapwing and, to a lesser degree, Dunlin. Shelduck sometimes haul out, and oddities such as Knot sometimes show. Rock Pipit, Kingfisher and the aforementioned Grey Wagtail sometimes loiter over the tide.

Where do they end up? Sometimes they flight to a nearby roost, at times of highest disturbance they can head for hard-to-view central roosts (which is mainly weekends, which in the past has been counted mid-week- a reason why counts on any large estuary should be co-ordinated, and why detailed supplemental counts at the various individual sites are useful, whether they be made available to local WeBS organiser, BirdTrack, or a county society).

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Finally, nice to catch up with the Sheldwot once more- clearly settled in for another winter off of the Strand.






Tuesday, 21 November 2017

Visible migration- no way as sexy as nocturnal

The BTO have made some of the resources used by ringers available to all, c/o their website. Among the useful papers is a description of the fat scores used by ringers. I've taken the liberty of highlighting how the two systems explained there differ.


The left-hand column (orange) carries a scoring system designed for migrating species. These birds are finely balanced; fat is deposited at both ends of the body to ensure optimal flight results are achieved- what would be the point to carrying lots of fat as fuel if you have to burn too much carrying it? The illustrations tie up perfectly.

The right-hand column (green) carries a scoring system best suited to resident birds which rarely have a need to carry out long journeys. This only scores the trachial pit (the throat), as these birds never really routinely deposit fat for flight and have no urgent need for balance at low scores. In fact, it has proved more useful to score the lower amounts at a different scale, as deposits are much more subtle. The green lines point to the illustration (where available) that best matches the fat deposit.

Ask a ringer if they've seen fat scores of eight- they'll name nocturnal migrant species, making long jumps. Ask them if they've ever seen a Blue Tit with that same high fat score. They won't have. Blue Tits, where they do migrate, do so diurnally.

There are wholescale physiological differences in nocturnal and diurnal migrants, for example, many of the former have adaptations to their blood that allow high altitude flights. Intriguingly, residents tend to have any stores of fat at a cost of slightly lower pectoral muscle scores than migrants- they really won't be looking to leave.

Diurnal species often have large percentages of resident birds within parts (usually the southern parts) of their range. There is a spectrum of movements, and the fun of deciding whether that coastal Tit is a continental or a local is never, ever as easy as we try to make it. Of course, we really want them to be continentals. But even on a day when a bird ringed on the continent turns up, congeners on the coast can just as likely be dispersing residents.

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From late June, migration to wintering areas starts. Mainly by nocturnal means. It goes over the heads of most birders. Why else have the greatest gathering of birders in the UK (the Birdfair) in mid-August? Not really missing much of the migration spectacle taking place at the same time, because we don't see it.

Come early October, viz mig sets in. The diurnals are coming. Shorter distance migrants, less faithful to one particular wintering area. They move about more during the winter period, in response to weather changes. Some only move in the first instance if there's problems with food supplies.

Us birders love viz mig, but we are often only looking at a part of migration.

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So, why is nocturnal migration seen as a better option than diurnal?

Diurnals don't have that star map.

Diurnals have to share feeding and migration during the same (daylight) periods.

Diurnals suffer a greater range of extremes (e.g. higher daytime temperatures) that really have knock-ons for optimal condition.

Diurnals use more energy for similar distances (those extremes take their toll).

Diurnals take longer to cover similar distances.

Diurnals have to put up with way more predators.

Just for a moment, think of those diurnal species as pioneering 'residents' now doing their utmost to take advantage of breeding habitats at the extremes, now retreating. Those nocturnals, they're premier league migrants.

This is, of course, an over-simplification, just a way of starting to make people think about what they are watching fly past. Because a lot of the joy of viz mig comes from wondering just what exactly we are seeing.


Monday, 20 November 2017

Visible migration; the all new adventures of Fallout Buoy

"Look above you, Fallout Boy- Geese!"
"Forget them Radioactive Man, Godwits back in the Creek"
Fallout- not a phrase that trips off the tongue this side of the pond, but a well-known phenomenon nonetheless- we tend to say a fall.

The fun is birds don't just do it as a response to hitting bad weather; they can use it as a landing tactic. For sure, many descend like an aeroplane, losing altitude as they approach their destination, but if they are flying over and see a habitat below that seems suitable, they can just drop. Our mindset may be visible migration and those diurnal migrants late in the season, but plenty are higher than we can spot, and plenty will drop in, night or day.

Works same way for long-distance migratory flights. Waders setting off from Africa, heading for the Waddenzee, often waste no time rising to a height of around three kilometres cruising height. All why if you tot up all those waders zooming up-Channel in spring, both sides of the water, you'll get nowhere near the true figure passing. Plenty will still be a kilometre or so up, only carrying out a fallout manoeuvre over their favourite bit of mudflat (radar studies have shown incoming heights in northern Germany at around the 900 metre mark).

Flight height. South coast ringers know some of the biggest day totals happen in conditions viz-migging birders give up on; clear skies, a slight sou'westerly. Migrants striking out for the continent, having travelled overnight from, say, the north of England, face choices at dawn. Can they see really good habitat for refuelling, or are they up for striking out for the continent? Fallout, from twilight's first gleaming. Why a reedbed might be full at dawn, why ringers' catches are best in the first few net rounds.

The 'dawn ascent'. Coastal ringers know second round is as good, sometimes better than the first. Birds are still arriving. Often at night migrating birds drop low over water. Some think they can take advantage of the wind conditions where waves of water and air meet. Some think they'd stay low in such circumstances in daylight, but rise to avoid predators (bloomin' seagulls again).

Makes viz-migging diurnal migrants over an estuary fun. You can say there's nothing moving, when in fact there could be plenty just that little bit too high. When it comes to thinking about waders and wildfowl, you start to have a whole new set of problems, especially once you're mid-season and birds are already in; what is inter-tidal movement, what is inter-staging area migration?

A whole new level of interpretation.

Some things help here on the Medway. The first movements of Brent Geese each autumn, birds bound for the south coast and beyond. Similarly a duck like Wigeon. For waders, first arrivals of adult breeding Grey Plovers is a good one. You are never going to get it 100% right, and you might be more than 50% wrong if truth were known, but a good understanding of flight behaviour will get you asking questions at the right time.

So, ducks and geese. High arrivals. Higher than flights for creek to creek tidal re-positioning. Why waste energy heading up when soon coming down? Escape flights- often lower than migration mode (wildfowlers would have hung up their guns by now if birds had evolved to equate height with fright). A longer flight, from one side of the estuary to the other? Well, these don't happen unless needed, so not a regular occurrence, but when they do, they can start to have central height- fun is to learn to spot the take-off.

Birds at a cruising altitude of a hundred feet or more (so good views of the estuary environs) following the deep water channel, falling out on 'safe landing zone' (more on this below) should ring alarm bells. Of course, birds could already have dropped low to the water out in the greater Thames; birds entering the Medway past Sheerness can be really low. You are never going to be able to tell for sure- but you can get a feel.

Waders? Play the same game with their inter-tidal movements, watch which birds favour which heights, and look for differences. Settled waders often do not travel long stretches of the main deep water channel. Incomers do, and often head mid-estuary for the 'safe landing zone'

Booze buoy- where fallouts happen

Yes, you might well pick up your first dates from shore in the well-known bays, the Rainham Saltings and the Funtons. But often this can be tide two back, or more, for returnees. They hit mid-estuary first. The flats of Ham Ooze, or Bishop Ooze, give them a chance to weigh up the situation. Even once the season is well under way, many birds remain as far from shore as they can. Why take unnecessary risks?

The BOOZE buoy- marking the western end of Bishop Ooze


So, watching from Horrid, no choice but to grit your teeth and look out into the sun early in the season. Look to the distant cranes, take the left hand end, that's roughly the start of the main Channel's drift down Kethole Reach; birds coming in straight towards you along that line, they're quite possibly movers.

From Horrid to Booze Buoy, a measly 3.6 km.
Just like grown up seawatching

That fallout buoy often gives a clue to intended inland movements as well. Take terns. They might gather fishing around Bishop Ooze, before starting a few high circling flights. Some keen to strike off, others not so, perhaps gathering courage for the off. On a low tide they might sit it out on the Ooze until the tide forces them airborne. You can get a feel a good couple of hours before they make their dash for it. Always between due west (taking Long Reach) and due south (inland over Rainham saltings making for the Downs). And they'll gain height overland. Half a kilometre or so will get them a view to further waters.

Of course, a lot of that could be totally misinterpreted. Go back 30 years and I can remember the often heated exchanges at local birder gatherings between the returners and the exiteers (Thames/Lower Hope- seabirds return back out east, they don't go overland- seabirds go east, at height). It all comes down to which school of thought your mind works under. Try to be open, and try to remember any type of movement is on a spectrum- some birds will do it one way, others of the same species another, and individuals might well change tactic under different conditions.

Any autumnal totals for wildfowl/wader migration just won't add up to anything meaningful. To that end, viz mig is a bit of a blow out here; but you can experience it here, and when you do, it's bloomin' wonderful; skeins of Brent, lines of Whimbrel, a rise of terns, all cutting in overland- a real joy.

Black-tails inland at dusk, Windmill Hill, 07/17

Common Terns inland over Gillingham, 08/17

Brent Geese inland over Moor Street, 09/17

Whimbrel inland over Lower Twydall, 08/17

Sunday, 19 November 2017

Visible migration- adjusting your position on it all

Seawatching? No thanks, I'd rather be bushwatching.

Bushwatching? Just turn that chair around to face inland, and watch those birds working through the bushes. Just like many early morning visible migrants are simply making a minor movement, seeking out a feeding spot, many birds can just feed and move, looking to find a safe spot during teh first few hours to allow them to rest up and ready themselves for the next leap home.

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"Morning flights of migrating birds relate to density of nocturnal migration and direction and speed of nocturnal winds aloft", a nice little study available as an easy-to-absorb chart here:




Their conclusions?

"Coastal morning flight migrants may be correcting for wind drift incurred at night.."

"Stopover habitat selection may also be a factor.."

"General aversion for the ocean is evident.." (substitute 'large estuary' for 'ocean' here)

"Further inland, possibly other functions (involved such as) continued migration.."

"Local topography also exerts bias.."

Yes, yes, yes, yes and yes!

"Future research: increased coverage, more inland locations, spring morning flight.." Oh heck, a spring spent out on Horrid? Let me think about that one.

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My favourite place on earth for bushwatching? Point Pelee, Canada. No question.

Favourite place in north Kent? Sadly no longer really exists. Grain Power Station.

A dozen or so football stadium style pylons on site. Lighthouse-style attractions. With permission, several years spent getting a few spindly sallows established among the walkways.

A first flush, walking under the pylon lights just on dawn. Migrants into our mist nets. Then the second round, almost as productive, as birds that had holed up in dark corners move out to try to find good feeding. Finally, a third wave that we called 'the dog walker express pulling into shoreline central'. Over the perimiter fence they came, a flush of warblers that had been happy in habitat outside, but now felt too many threats to rest up. After the first two or three hours, all over. A trip to the western parts of the site, around the human-free scrubby water tank compound, would find a lot of birds.

Happy days.

Here on the South Medway? Horrid Hill? Nope.

Sharps Green. You've got one shot. Limited early morning parking keeps visitor numbers down at first, but there's a few die-hard locals who will be out, even pre-dawn. Most will stick to the paved paths at first, until the light is really good. Find your spot, a little ways in from the shore, where there's a nice hedgerow effect. And wait. On a good day, the waves get pushed through the area. All over after the first hour, but that good day will get you a total of 30, 40, 50 warblers. Less than you'll get elsewhere on the north Kent coast, but more than enough to keep you happy.

Saturday, 18 November 2017

Visible migration; Horrid results for nocturnal migrants

In particular, the 'crests and warblers. Helping to show we do see a small amount of fallout on Horrid, but never in great numbers- you have to work for it.

Phylloscopus warblers: first movers are the Willow Warblers- Brits moving through, no late Scandis, all over by mid-September. Perversely, as easy/easier to find a WilWa on Horrid as elsewhere in the Park. Birds there can easily adjust position after arriving, moving through the Park trying to find a nice place to rest up. Birds dropping onto Horrid overnight tend to sit tight. Often they do not even want to make the short dash along the treeless narrow neck.

Early numbers of Chiffchaffs are in all probability the result of local breeding- wandering young. From mid-September numbers drift upwards. If lucky, one might come 'in-off' at dawn, or a bird might turn up on the adjacent saltings. The Point did not attract large numbers, however, but enough to help chart the peak.


Acrocephalus warblers were virtually non-existent on the Point- the habitat just not right, and the weather too good during their main movement period (through August into September) to have more than the odd bird drop into the bushes. Step off the Point and watch at Sharp's Green Pond instead- ten minutes on a good day will often throw up a double figure count.

Similarly the Sylvia warblers also trickle through only until the time the locally bred young have also gone. Nothing to make you feel the Point reflects their migration. Only one fair-sized fall of Blackcap.


Thankfully the Regulus, the 'crests, can show you a little pulse of their migration:



And the odd bird does flutter in after dawn. Horrid is no coastal viewpoint, but if life gives you lemons, learn to enjoy the taste. If you can manage that, you can see migration in action out there. As I've said before, the rest of the Park can throw you up many more migrants, but the feeling when you stumble of a lone warbler out on Horrid is just as strong. 

Friday, 17 November 2017

Visible migration; Horrid results for other diurnal migrants

And now, in no particular order*, a pot-pourri of diurnal migrants showing the pros- and cons- of viz-migging at Horrid.
(*Well, it's actually alphabetical from cutting and pasting the series of screenshots. You've caught me. But it's late and I can't be bothered to shuffle them right now)

Grey Wagtail

(Holloway, 1985; All known records are from autumn and apart from a few birds flying west most have been in the Sharpe's Green area.)
(Davenport, in Oliver, 1991; (from) middle September.. occasional Grey Wagtails can be heard flying over in the early mornings..)
Heads or tails, this one. Either there is a small passage, or there's a small roost nearby. Well, there is a small one, double figures, but to the east. And these Horrid birds invariably move west to east (downstream). I'll keep dreaming they're all movers..

Marsh Harrier

(Holloway, 1985; Just two records, both in the autumn..)
(Davenport, in Oliver, 1991; in the second week of August.. (they) begin to appear.. although their peak numbers are invariably to be seen at the end of the month..)
Let's go for a big 'un now. Everyone likes a BoP. Well, nearly everyone, I've never understood the fascination. Still, at least big and easy to identify. And all going west. Problem with this, as you watch them cross from Ham Green towards Hoo, is you have that nagging doubt in your mind because you know there are roosts just a little to the east. A doubt that becomes a shout when you watch in the evenings and see the odd bird crossing back. Ah well, if I see four or more in a morning I *might* just think I have some movers, otherwise nothing to see here, move along..

Meadow Pipit

(Holloway, 1985; Large numbers sometimes present in the autumn..)
(Davenport, in Oliver, 1991; (one of) the most typical migrants of the last two weeks of September and first week of October.. )
Oh, here we go, a species known for migration over coastal marshes. If you enjoy your specks, you'll enjoy this! Because about eighty per cent of the movement is westward over the islands. What self-respecting Mipit would want to follow the shoreline when there's marsh out there? The question I want to ask is which route do these birds take when they reach the head of the estuary?

Pied Wagtail

(Holloway, 1985; no comment on autumn migration)
(Davenport, in Oliver, 1991; (from) middle September.. occasional Pied Wagtails can be heard flying over in the early mornings..)

I've included PieWa because it was the species where I kept asking myself 'where are they?' Only when I switched to routinely including an hour onshore at the Mound did I realise that an awful lot of their movement avoided water. So, with a reasonably-sized roost a mile away, did any of these day totals shout 'movement' at me? At the time, no. Totals lower than I'd expected, but at least a pulse could be seen. Next autumn, wherever I watch, I'll be gunning for a 20 bird day to be able to say 'I was there when the Pied Wags really moved.' Until then..

Reed Bunting

(Holloway, 1985; no comment)
(Davenport, in Oliver, 1991; no comment)

My favourite memory from that autumn three decades back was of the Reed Buntings roosting in the low scrub. Praise the Lord, they were still there! Nowhere near the numbers back then, but still there, and still roosting.

Rock Pipit

(Holloway, 1985; no comment)
(Davenport, in Oliver, 1991; no comment)
A species where I felt I learnt a thing or two. All too often this winter visitor gets recorded religious on the first date of the autumn then becomes just a 'regular' on the day list. So, really interesting to pick up on the pulse dates, tying in nicely with 'B.W.P's Oct-Nov comments.

Sandwich Tern

(Holloway, 1985; more frequently seen in autumn when small family parties can sometimes be seen flying over..)
(Davenport, in Oliver, 1991; second half of July sees start of Tern passage, when the first few appear..)
A sad one. A brilliant movement by Medway inner basin standards, but only brilliant because not one local could think of a recent year like it. What was going on? To me, this was a return to the Holloway days, before a ccolony existed in the Medway. Ever the miserable beggar, I could only come up with the idea that some of the pre-'17 breeders that had deserted this year were passing by to check up on what was happening. And every time a pulse went through I asked myself if that was it or they'd do the same come 2018. Watch this space.

Skylark

(Holloway, 1985; no comment)
(Davenport, in Oliver, 1991; last three weeks of October and first two weeks of November.. is the season for large visible movements..)
Really thought there'd be more. This was one of those species you always register passing in the autumn, yet these numbers were nothing to write home about. Perhaps more move on the northern shore, or perhaps they turn south before the suburbs?

Sparrowhawk

(Holloway, 1985; no comment)
(Davenport, in Oliver, 1991; last three weeks of October and first two weeks of November.. occasional..)
Nope. Didn't happen. Always next year..

Thursday, 16 November 2017

Visible migration; Horrid results for the thrushes

Fot this blogpost, we can get the old Medway texts out of the way right at the start:

Holloway (1985): (migration not mentioned!)
Davenport (in Oliver, 1991): "..at the same time (last three weeks October/first two weeks November) calm, misty days might produce overnight falls of Blackbirds, Song Thrushes and Redwings.. while the continuous calls of these three species migrating overhead typify many autumn nights.."


Blackbird


This typifies the problems here. We know the numbers come in from the continent, but as a mainly nocturnal migrant it is hard to pick out the arrivals. There were few peaks out on the Point of Horrid Hill, but prior to that the small build in numbers through the season more likely reflect local dispersal and a breakdown in size of defended territories.

The one thing I'll also mention is our subconscious desire for birds to be migrants. 'Scaly' plumaged Blackbirds must be continentals. Dark billed birds must be continentals. Nope.

Since I moved back, local orchard ringing of a very late brood of Blackbirds saw a nice retrap of a scaly youngster late in the autumn. Several years ago another ringer had a breeding Scaly bird on the Hoo peninsula. As for bills, birds from late broods keep them much later than early brood birds. We cannot assume such birds are 'contis', we just wish they are. They might well be, but we can't presume.


Fieldfare

Well I wouldn't have forecast this graph a few years back, bearing in mind the good ol' days at Grain when flights over the Thames often appeared; here, none crossed the Medway estuary waters this year. The only movements recorded were from the mound on the southern shore itself.



I have a theory (when you have so much thinking time on a viz mig watch, such things happen).


For the past five autumns, my first Fieldfares along the southern Medway have been birds in, or over, orchards. Why that would be, when they don't start on the windfall until later, is hard to suss; perhaps it mimics a favoured habitat? Who knows? The white circles note my sightings for first three dates each autumn, all in orchards. (The northern half of the Ham Green peninsula is a main attraction.)

So, birds at the end of their migratory flights might head for this habitat (certainly in spring I've had flocks cross north from Ham). Flighting autumn birds often move from this area to just inland out of sight of my two Horrid watchpoints; they do cross from Ham to Motney and sometimes to Bloors, but look to the orchards just south of the estuary wall for their flightlines. The few days I have a major pump, I wonder what it would be like if I were watching just south of the railway line around Pump Lane..

A reminder that one small observation point can show viz mig, but may well not tell the full story of the viz mig in progress.


Song Thrush

I blame my years living among flood plain fields in East Sussex for Song Thrush being my favourite migrant thrush. From Horrid hard to spot the movement unless you look daily, but it appears to be discernible here (just).

In general, Song Thrush have a steady (broad) route along the shore, or just inland. Back in 2013, mapped the route south-west of the Medway Towns, as if some really didn't like the concept of overflying urban sites unless they had to. If still truly 'migrating', overflying the Towns during the first few hours of daylight would surely not be as great a deterrent?




Redwing



Only picking up one big arrival was a pain, but it went the way things do; a big south- southwesterly element to the flight, high in over the water at first light. Otherwise, the (mainly) westerly tracking evident in all of the smaller daily movements.

As with Fieldfare, autumn movements more easily noticed over better habitat inland of the estuary.

Of course, both Redwing and Fieldfare are great cold weather movers in this part of the world. Arrivals can be late, returns can be immediate; Lack's radar studies in the sixties showed flocks of these (and Starlings) crossing from the continent one night, flocks moving back as soon as the thaw set in. Why roosts for all three can be temporary and fickle around here.

(Now do I make that my excuse to make 2018's viz mig season last from mid-June to December 31st?)

Wednesday, 15 November 2017

Visible migration; Horrid results for the finches

The question- is visible migration worth studying along the south Medway? The results from this year's early morning counts at the point of Horrid Hill (plus, from early October, a second spell on the Mound at the base) have provided some useful support to findings made at other sites on the south Medway since autumn 2013.

The opening quotes for each species are from John Holoway's 'Birds of Gillingham', and then Dave Davenport's chapter on migration from Oliver's 'Bird watching on the North Kent Marshes'. The graphs are this years Horrid Hill figures, whilst the maps, unless otherwise stated, are based on cumulative observations for the whole southern shoreline over the past five autumns.


Chaffinch

Holloway (1985): "..flocks are often seen along the river and on farmland in autumn and winter.."
Davenport (in Oliver, 1991): "..last three weeks of October and first two weeks of November produce the main westerly passage.."

Chaffinch has been an eye-opener for me for many years, ever since bumbling over the finding that the majority of 'finks overwintering in the U.K. enter via the south-east, unlike Bramblings that mainly come from the north.



It is certainly a great example of east-west visible migration. Previous autumns, east and south-east of Horrid, have shown just how strong that movement can be. Often the biggest counts happen the day after east coast sites such as Pegwell have their big arrivals, as if they are putting down within an hour or so of crossing the Channel.


Brambling

Holloway (1985): "..occasionally seen with Chaffinches in the winter months.."
Davenport (in Oliver, 1991): "as Chaffinch.. accompanied by smaller numbers.. main arrivals equally likely to occur in early November.. frequently associated with hard winters.. when.. takes to feeding on the saltings or along the sea walls.."

A species that never regularly turns up in numbers in the autumn, one that is more prone to see cold weather movements later in the year. Whether these later movements are from birds already in the UK, from the north, or further immigration from the near continent, is difficult to say. The autumn birds here are tied in with the onshore Chaffinch pulses and should be considered as 'fellow travellers', as the majority of Brambling arrivals come in over the northern North Sea.


Greenfinch

Holloway (1985): "..widespread.."
Davenport (in Oliver, 1991): not mentioned.


Another species many believe comes over in numbers, but one that ringing evidence says 'no'. Certainly these grounded birds were only coming out to the Point on Horrid to feed; stay long enough and you would see them return to the same spot on the 'mainland' most days. Any peak could just as likely be down to local dispersal.


Goldfinch

Holloway (1985): "..fairly common.."
Davenport (in Oliver, 1991): "..increasing numbers (in October).."


Although the past few years have picked up a definite 'southerly' feel to autumn flights, perhaps indicating a larger element of emigration rather than immigration, the local topography creates a south-west movement inland. Goldfinches at the Point are more likely to be coming in from a northerly vector than most finch species reviewed here.


In previous decades wintering numbers were much lower, so picking up movement late in the season was easier, but there are now several areas where Goldfinches remain in fair numbers throughout the autumn; local ringing has shown some local breeders to be sedentary. To that end, daily roost flights have to be considered when considering possible viz mig; these roosts grow in size from early September onwards.


Linnet

Holloway (1985): "..can be seen along the Medway at any time of the year.."
Davenport (in Oliver, 1991): "..on some October days.. southerly movements of Linnets.."


Very similar general comments to Goldfinch, with a nice southerly trend to flights. However, many more feeding flights to the island saltings, so difficult to pick out viz mig; roosting habitat preferences, such as dense bramble, are not found on many of the islands and the short duration of the main southerly pulse points towards an ability to pick up on viz mig.


Siskin

Holloway (1985): "..very uncommon migrant but in October 1983 there was a large passage.. flocks of 20 or so could be seen flying west.."
Davenport (in Oliver, 1991): "..last three weeks of October and first two weeks of November.. season for (large visible movements) accompanied by smaller numbers of.. Siskins.."


No shocks with this graph; not a Siskin autumn. This species (and the following) have a large element of irruptive nomadism to their seasonal movements. Irruptive, because they work from local food source to local food source- there is no promise of food at the end of a long migration to the same spot as the previous winter; why, for example, Scandinavian breeders might first move south then possibly move west, or east, later into the winter.


Lesser Redpoll

Holloway (1985): "..occasionally seen with other finches in winter.."
Davenport (in Oliver, 1991): Not mentioned.



Siskin and Redpoll could almost be lumped for viz mig comments. Again, feeding further north must have been good at the start of the autumn (ringing has shown that many birds in the south-east in autumn have come from within the UK).

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In conclusion, diurnal movements of finches, although nowhere near as strong as along the Thames, itself nowhere no as strong as further east in the county, is observable on the estuary, and regular watches can turn up the odd 'big day'. Even if these results don't fill you with any urge to rush to the Medway, bear in mind the Thames is woefully under-watched these days; despite the adverse comments places like Grain seem to receive on an annual basis on social media, the birds are still passing there. Lower Hope Point at Cliffe, Allhallows, Sheerness on the island, all spots where viz mig awaits to be recorded fully again.