Foggy thinking

For the past few days my covering tide counts have been messed about by fog. Hasn't stopped me counting though- with my mantra still being 'don't count for the number, count to understand' there was something to learn out there.

Sure, my main interest, inter-tidal movements, was knocked for six with the resultant low counts, but the birds were still out there, somewhere.

Like me, they had limited vision. Although I'm trying to understand nocturnal as well as diurnal movements, and know wader eyesight has evolved to aid feeding, migration,etc. in extremely poor light, they still don't have a great ability to deal with fog, which is essentially water droplets hanging in the air, impeding any clear view regardless of their light-gathering capabilities.

Fog comes in lots of shapes. Birders probably encounter radiation fog in winter more than any other form during cold, calm conditions. It forms as the ground cools further at night thanks to conduction. It usually forms later into the night, lasting into the morning when the warming sun 'burns it off'.

Precisely what had happened night before last. Clear until the wee small hours* when the tide was dropping and birds would have moved to their 'usual' night areas.
(*An old phrase referring to the time that old people have to get up and visit the loo during the night, and can look out to check the weather...).

So, the early morning onset of fog would see birds trying to roost in limited visibility.

Individual waders that hold a feeding territory can retain some normality, similarly species that do not follow the tide. But those that chase the tide out, that might flight from one flat to another, could well have problems reaching their normal roosts.

Safe roosting is vital. A place to rest, a place for information exchange. A lot has to be taken into account when trying to avoid impacts on the carrying capacity of an internationally important estuary.

Waders are never 100% faithful to one roost site. They have different options for neap and spring tides. Similarly for nocturnal, diurnal roosts- many birds might choose to continue to feed on the roost in daylight, many sleep for longer periods at night and need the safest of sites. Within these choices, they might also swap due to disturbance levels (there is a clear difference on the Medway between weekends and weekdays, thanks to the increases in human disturbance levels out on and around the islands). Annual cycles also have an effect, for example, pre-migratory restlessness causing larger communal roosts.

Ideally, all main roosts on an estuary should be found and recorded, with an assessment of quality and of usage frequency. Distances from roosting to feeding areas calculated, and the availability of secondary sites should any become unavailable. Piecemeal development around an estuary can easily impact on carrying capacities.

What happens in fog? What might a birder experience?

Individual waders holding feeding territories often stay close to their patch of mudflat, retreating to the sea wall. More than likely these will be the lone Grey Plovers, Curlews, Redshanks you put up.

Communal roosters may have to try to hole up adjacent to their last feeding area. Birds such as Dunlin and Black-tailed Godwit will be clumped together in small gatherings of perhaps 100, 200 birds, on the saltings, or tucked up close to the seawall (neap tides under fog better for observing this- more saltings available to keep a dry foothold on).

Of course, any observer might cause a disturbance movement. Stumbling upon a lone Grey Plover the bird might rise up, calling, to flight a short distance along the wall. A clump of ten, twenty Grey Plovers (non-territory holding birds) might well do similar.

Flushed birds might drop inland of the seawall with an intent to return as soon as you have passed, or try to circle tightly overhead, calling frequently. Rarely will they attempt to go any distance, unless they consider you a real threat.

Wander enough of the seawall, and you will find many small roosts on what are usually unsuitable saltings. Wander often enough, and you'll find which ones are routine secondary sites.

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I have most experience of foggy behaviour for Rainham creek/saltings and Otterham simply because they are the sites closest to home; much less chance of me getting run down walking/cycling that short distance to the seawall than risking foggy rat-run back roads during an early morning rush hour(!)

One obvious candidate for a case study here at certain times of the year is the Black-tailed Godwit. When on the estuary in number, they might not always find fog binds them close to shore; they may have been favouring mid-estuary feeding when the fog descended. But if they find themselves fogbound when in and around Rainham and Otterham Creeks, to my eyes they will adopt a restricted flight routine.

Foggy morning roosts will be Rainham Docks East for Rainham Creek feeders (red), Otterham saltings for Otterham Creek feeders (orange). The former site suffers from high disturbance levels, being within the Countryside Park and close to one of the main car parks. Birds might try to navigate north to RSPB Motney Hill saltings, but more often than not go low over Motney peninsula reed bed and scrub to join their neighbours. There the low-lying Otterham saltings, like those of Motney Hill, go under on higher tides. Birds might then often choose to drop over the sea wall onto the fields of Horsham Marsh.

If the fog persists through the dropping tide the birds then remain in the northern section of Otterham Creek (away from any existing footpaths), lining both edges of the creek.

This is the pattern for covering tides around dawn. High tides at night see the largest numbers of Black-taileds using either Motney, or more often Oakham island mid-estuary. Fog at this time means many fewer Godwits close to the southern shore at dawn.

Just after sunrise, on the fall, Rainham Docks East, April 2014,
following an undisturbed roost along the shore.

All vastly over-simplified of course (a further secondary roost on Motney has been left out to avoid confusing flightlines) but hopefully a useful example of how recording site usage around your own local patches can help. It will help clear the fog a bit.

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An example of how powers that be may well miss such things when planning future developments if we birders don't clear the foggy thinking- take this published quote from a professional consultancy report for landowners regarding a stretch of seemingly uninviting man-made stretch of north shore seawall. An area which I've found to be used routinely by large numbers of roosting Oystercatchers; on spring tides, when disturbed or under certain weather conditions. I've pasted the quote on my picture of these Oiks- they're the specks along the concrete apron in this shot taken from Horrid Hill on the south shore.

The more we find out, the more there is to know.

Curlews- the long and the short of it

As you've probably noticed, I'm no photographer. Record pics only. If I get a hundred metres from the house before realising I've left my camera behind, I carry on regardless, I'm out to bird. I do sometimes regret it.

The other morning I was cursing at the Curlews for catching me out. Some had clearly just changed behaviour. In the hour after dawn, small groups were coming off of the roost fields around Ham Green and flying low, to the south and inland, over Windmill Hill.

I'm no scientist... so my mind immediately went 'migration?' Mid-winter readjustment, birds moving south? Couldn't be. Most studies have shown this species migrates directly and quickly between breeding grounds and wintering sites. They don't re-adjust. It took me a minute or three to recall the actual behaviour I was seeing.

Some Curlew change their feeding behaviour as the winter progresses. For a few weeks now, bang on time, further east along the estuary more and more Curlews had been found feeding routinely on the fields of Raspberry Hill. Their main prey in the mudflats, ragworms, are a lot harder to find around now, and earthworms become more important in their diet.

It is not because the estuary food is running out. Yes, the ragworms are somewhat depleted, but they become harder to locate as they bury themselves deeper in the mud in colder weather. In very rough terms, the longer-billed females can still find enough out on the mud, but shorter-billed males find the going tougher and it is mainly these males that switch to the fields.

So, there should a drop in numbers feeding out on the mudflats during the low tide cycle in mid-winter as birds head for the fields in daylight hours. And there is, with peaks of 'inland feeding coming during late December. Easy to see around Raspberry Hill, grassy fields are close-by the flats. Travel west, between Upchurch and Lower Halstow, and flocks are often encountered around Green Farm and Holywell Farm. But on the inner estuary, where exactly do commuting Curlews go? And as more fields are lost, can males cope? Just how far are they prepared to fly inland to feed before the Medway begins to look unattractive as a wintering site?

Ortstreue. Another of those lovely German ornithological terms that you stumble upon in textbooks as you try to find answers to such questions. 'Ort' + 'streue' =  'Place' + 'scatter'. "Winter ortstreue of Curlews is probably strong", says volume III of 'The Birds of the Western Palearctic'. Fidelity to a territory, at both ends of the migration route- Curlews stick to a home territory and a winter territory. Makes sense, why many Curlews do not feed as a flock but claim a wintering territory on the flats and then defend it against others. A wintering short-billed bird, that has found both mudflat and grassland in one winter, will probably head straight back for that area the next year.

The day after I'd failed to get the pic was Boxing Day. Out the front door 20 minutes before sun up, no commuter traffic noise, the Medway Towns were sleeping. Turning into Otterham Quay Lane, first birds heard? Curlew, south. Lost the cries towards Meresborough, probably went beyond. (And, yup, the camera card had been back in my PC.)

How much surrounding development can an estuary take before short-billeds find the going too tough? The texts hint at a maximum distance Curlews seem willing to try being around 15 miles.

Tonight I got the chance to watch that Windmill Hill flightline back. They came back in one large group about ten minutes after sunset, quiet, fast, and low, dropping into Otterham Creek on the flats near the sewage farm. (And, yup, I'd already put my camera away. Civil twilight and all that.)

I really am no photographer, but I do want a shot of the behaviour locally now. For this blogpost I've had to make do with a snap from three winters ago, when these Otterham Curlews could still be lazy and fly all of a hundred metres onto Motney, back when the grass was short, back when I'd never knowingly picked up on a mid-winter commuter route over Windmill Hill.

Motney Hill, December 2013

A twilight saga

While composing yesterday's post on Golden Plovers, I found myself querying my own understanding of 'dusk' and 'dawn', and whether I ever use them correctly.

"The Lapwings flew back to the estuary just before dawn."

So Mr. Thornton, it must have been completely dark and you can have only heard them, because-

Dawn is, officially, the time from the start of twilight to sunrise (and dusk the time from sunset to the end of twilight).

And twilight is the illumination of the atmosphere while the sun is below the horizon- any time our sky has some light in it. There are three clearly defined elements to twilight- first-

  - astronomical twilight: this starts when faint astronomical objects, such as nebulae, disappear. (Of course, light pollution messes this right up and we struggle to see such things) This period lasts until-

  - nautical twilight: starts when sailors can pick out and use the horizon for navigation. This middle period lasts until-

  - civil twilight: when you start to distinguish 'terrestrial objects'. (This is the one we come upon most frequently with respect to civil law- street lighting times, when we must have car lights on, etc.) It ends with-

Sunrise, the instance the upper edge of the sun appears above the horizon. Technically, sunrise lasts for just a fleeting moment. All those photos we see labelled 'sunrise over the estuary', or similar, are wrong- the sun has already risen. (Yup, that includes all of mine. My bad.)

Does this all matter? Not really, unless, like me, you are looking to make sense of bird behaviour. As I first typed this, during dusk, a Robin was tac-ing in the garden. Civil twilight. As I proof-read this, said Robin had gone quiet, in nautical twilight. Knowing those definitions help make a more specific interpretation of the event. Must try harder- I cannot remember the last time I said 'twilight' though.

Back to those Lapwings, flying back to the estuary, just 'before dawn'.

It wasn't just before dawn, it happened a long time after dawn had started. I could make them out above the treeline. It was during civil twilight. With their far superior eyesight, the Lapwings would have been seeing everything extremely well by this point.

Oh, and just to add to the fun. The angle of the earth, at different times of year, increases the length of each of those twilight periods during the summer months, to such an extent that anywhere on the globe above 48.5 degrees north (that's us here in Blighty) has dusk run into dawn- twilight never stops, complete darkness never happens. No wonder many birds can remain active 'at night' in the late spring(!)

Around midnight on our marshes, light pollution always plays a role. Even on a new moon, reflected artificial light off low cloud means you can see reasonably well to walk the marshes. It hardly ever gets dark. Bird activity is affected.

Only once recently has a nocturnal walk around here gone truly dark, when a sudden fog descended during a ringing session; the light from the Medway Towns could no longer reach me and, unlike that grey fog we get used to around town under streetlights, this was black, really black. Navigating my way back around the creeks that night was a fun experience I have no wish to try again in a hurry.

Finally, before anyone asks- night lasts from when the sun disappears completely from view to when the sun first reappears- sunset to sunrise. Those Lapwings were flying at night, but they could be seen clear as day.

Happy solstice everyone.

Goldie flocks

"In the Thames, and perhaps to a lesser extent the Medway, the first arrivals after a brief spell about the marshes and saltings pass on to the upland fields, whereas along the Swale they not only spend the whole winter in the marshes but regularly visit the saltings and mud-flats. This latter habit is certainly not confined merely to newly-arrived birds, but is noticeable with some of the winter population...
...Dr. J.M.Harrison, writing in the South-Eastern Bird Report for 1937, considered that the visits of the Golden Plover to the saltings and mud-flats of the north Kent coast were rare and limited to odd birds. We agree in general this is correct, but it does not apply to the same extent when they first arrive or during their stay along the Swale and a certain portion of the Medway..."

The Birds of the North Kent Marshes

E.H.Gillham & R.C.Homes, 1950

A sixty-six year old conundrum, which some texts point to now being solved. And a behaviour which certainly still happens on a 'certain portion' of the Medway.

On the mudflats

The first Goldies usually turn up late July/early August, almost always found on the undulating hard flats just south of the remaining saltings on the edge of Bedlams Bottom. The first birds are mostly adults, already showing body moult. Over the next few weeks these numbers build to just around the 200 mark, and remain about this level until the expected early winter influx. This pattern mirrors similar small arrivals at more westerly sites around the eastern Swale.

First returning birds, July 2016

What are their most probable origins? 'BWP' stated British birds to be 'partial migrants' with part of the population wintering in lowlands close to their breeding sites. The Icelandic population moves through Ireland and western Britain. The most likely source for Kent Goldies at this time is Fenno-Scandinavia/Russia, in line with the results from more extensive ringing efforts just over the Channel in the Low Countries. A bird ringed in September 1967 on the North Kent Marshes was shot whilst wintering in Spain in February 1969. The Dutch ringing scheme has a large number of Norwegian records from this time of year.

Will they continue south eventually? Well, the numbers remain level on the flats for the next couple of months, but the chances are we are seeing staging birds, small numbers staying for a few weeks then moving on. The moult strategy for flight feathers is attuned to this; a start before autumn migration, a suspension for several weeks during migration, only completing on arrival at the wintering grounds.

During these first weeks back on the Medway the birds will try to see out high tide on those small islands; if there are spring tides, they go under, so the birds make for Chetney. Otherwise they stay close to the flats. When on the mud, the birds are loafing for 95% of the time. Often it is like counting Meerkats- heads pop up from behind the mounds, and back down quickly again. The distance means they can be missed without a telescope. The rising tide, from around the 2.75 mark, does tend to force them out into view for a short while. The move to roost is more usually as one flock, but they can break into two/three groups to a pre-roost assembly on the flats just north of the islands for a short period.

Part of the flats loafing flock, viewed distantly from Raspberry Hill, November 2016

Feeding activity on the flats is just about non-existent, suggesting the mud is being used just as a safe loafing ground. After working that out slowly for myself, was pleased to see the excellent Poyser monograph quotes studies that have reached the same conclusion. Birds on the mud during the day are thought to be well-fed. It also quotes studies saying juveniles more often use mudflats, but that has not been the case with first arrivals at Bedlams in the last few years. Many species have higher mortality rates in first winter birds, but checking Golden Plover on BTO Birdfacts this is one area for which we still have insufficient data from which to draw results.

The general trend for Goldies in s-e England is for an increase in numbers after moult, often coinciding with the onset of colder winter weather. Further hard weather influxes may occur, but in recent years numbers are generally plateauing from late November.

On the fields

By this time the Medway counts are into four figures. These larger numbers stick, for the main, to the permanent grasslands of Chetney Marsh, where they also feed as well as loaf during the day. They will sometimes partly/wholly move west to the ploughed fields on north-east Barksore. Interestingly, counts of birds on the mud at low tide remain fairly consistent at between 2-300 birds, but on one date this month over the full moon period I counted just over 700.

The Chetney loafing site remains constant, west of the pylon line, with feeding there and through the grassy fields west to Stangate creek. The loafing flock is, for the main, single species; when feeding the birds are mixed in with the much larger numbers of Lapwing. The birds do not suffer close approach, and generally remain a field or so north of the Saxon shore way footpath.

The loafing flock, January 2014

Feeding at night

Perhaps there is enough feeding close to these areas- Chetney marshes are now deliberately grazed by horses to ensure a less tight sward. But it likely these birds, as elsewhere, might well have a much larger feeding area. Whilst some of the more suitable fields just inland to the south have been lost to solar farming of late, talking with some local landowners, numbers do use fields south of Funton at night. They all agree numbers in recent years have been much lower than in earlier decades.

It is easy to first speculate the Bedlams Bottom birds are birds that feed south at night, whilst the main numbers can get by quite well on Chetney feeding day and night. But peaks of birds on the mud suggest otherwise.

One important factor that affects nocturnal feeding is the state of the moon; more Lapwing and Golden Plover feed at night under a full moon than a new. the additional light aids their searching. Theoretically, the 'flats' birds might need to feed more in daylight hours, but I have not noticed any change in numbers tied to the lunar cycle. Better night feeding around the full moon might cause a few more birds to switch to the safer(?) flats to day roost.

For several years I was lucky enough to live on a farm among fields perfect for Lapwing. Birds would arrive an hour or so after the end of twilight, but often largest numbers would only be present for a couple of hours; I suspected that if feeding was good they would be in and out and back to safe loafing areas as soon as possible. Darkest nights saw lowest numbers, and birds staying longer.

Both Golden Plover and Lapwing can become active more than 50 minutes before dawn. About 20 minutes before dawn they gather together, then on dawn they disperse to continue feeding if needs be. Here, watches during twilight/dawn have confirmed large movements of Lapwing flighting back to Chetney/Barksore from farmland to the south. Goldies have featured, but never in large groups.

The more you learn, the more there is to find out.

The future

It is clear that the larger scale urbanisation/development further west along the southern estuary have removed nearly all the suitable feeding habitat; continued loss/changes in use of the farmland between the Medway Towns and Sittingbourne could well have an impact on the carrying capacity of the Estuary for both these species (plus Curlew and Snipe). In recent times changes in field usage alongside the Thames led to the decline of the Cliffe birds (that would loaf out on the Higham Bight mudflats). Just this week, between the drafting and posting of this blog I have seen twitter feeds making reference to a need for more work on nocturnal core areas in consultancy surveys, which is a heartening development.

Around the estuary

So, from data Chetney and Funton would appear to have been Gillham and Homes' 'certain portion of the Medway' more than sixty years ago. For Rainham, Prentis, in the 1880's commented that 'November is the month for the Golden Plover, their arrival is most uncertain, some years they are tolerably plentiful, others very scarce. They frequent the plough fields, fly together in company of an evening over the low hedges, where they may be intercepted and shot...'  A century later and Holloway conclusions for the Gillingham district were 'a few birds are seen on migration each year particularly in autumn but the species is surprisingly scarce during the winter when a few may be seen during hard weather...'

Looking at the published county records up until my return to Medway, Golden Plover may have been a less regular visitor until the grazing on Chetney changed to a more Plover-friendly regime. This main roost area is on a game shoot. The are still legal quarry in the UK, but it is not known if Plovers are taken regularly there- a recent article in the Shooting Times stated they are shot rarely in the UK nowadays.

Records further up the estuary remain quite scarce- the odd bird or two in autumn passing south overhead, or perhaps a displaced traveler during harder weather is really about all a watcher in the Medway Towns can hope for. Much better to get to Chetney and enjoy the distant spectacle.

Part of the Chetney flock, December 2014

Thin end of the salt-wedge- Flood Risk and Shoreline Management Plans

Salt-wedge: "Seawater intrusion in an estuary as a wedge-shaped bottom layer which hardly mixes with the overlying fresh water layer." Now we don't have much of a salt-wedge in the Medway, thanks to the strength of the tidal current, but in a hundred years, who knows?

In a hundred years, or in 2100 to be precise, things are going to be very different. And not for the better. That's official.

This Environment Agency plan has been out for several years now- previous edition was 2009, when I was living down in Rye and had my eye off the ball to such things. Today's update (coming in at 230 pages, but easily searchable c/o the Ctrl+F function ;-) ) has been publicised heavily for the amount of money to be spent down sarf compared to the rest of the country. Even more locally, it has one clear warning. The Medway WILL suffer for the protection of the capital. Forget all the international protection levels. It will suffer. Some mitigation might help wildlife elsewhere within the Greater Thames, but the next generations will lose our spectacle we have now.

Am I in uproar? Not really.

Seen it coming. The report is only saying what we've known for years. The cynic in me has joked with other birders for a long time about why efforts to protect our local habitats and existing reserves have been so poor here- because those in the know, knew all this. Global warming and tidal rise will do for this estuary as we know it. For the insignificant time I have left, I'll just keep on watching and recording. I've most probably less than a score of good years in me, I might just see out the good times. What the custodians of our marshes do in that same timescale will be interesting to observe as well.

Of course, there is a existing plan for Shoreline Management on the Medway, last amended in 2010. Not so glossy. There is a lot more detail of potential knock ons for the environment well worth any birder perusing but, for all of us along the southern shore, the summary:

This all plays second fiddle to what happens on the Thames of course. Interesting to note the final strategy policy report for the Medway is supposedly being finalised this month, then to signed off in the spring when, presumably, our own glossier amended report made available just after that. I'm already looking forward to that summary. In the meantime, here's the existing report's land at risk on the Medway. Will a lot of that will be coloured watery blue in years to come? We live in interesting times.

Mud and guts

Got to Funton for dawn. The tide was due to cover within an hour of sun up. Always makes for an interesting count as many waders were not in the 'right position' for the particular tidal state- overnight feeding behaviour is often very different from during the day, and many birds do not switch- usually makes for low numbers, so a quick count and a chance to do some actual birdwatching.

Wildfowl were about right; the water is their loafing zone, the only thing really different from my last visit the birds were extremely close to the vacant wildfowlers' blinds. At the weekend they'd kept their distance. A big distance.

Counts finished, I became absorbed with a life-and-death struggle worthy of any natural history documentary.

A Great Black-backed Gull swam into The Shade holding a duck in its bill, struggling and splashing. The duck was being held down in the water, and was having trouble keeping head above water. But the Gull did not appear to be trying to drown it. Halfway over, the Gull adjusted grip and, for a split second, the prey was free- but grabbed before it could do much more than flap halfheartedly a couple of times. As they neared the Chetney shore it did manage to break away; turning back and diving underwater in a vain attempt to hide. The Gull simply paused, stared and stretched out to pull the bird back above the surface.

By now I could make out the victim was a Teal.

It was carried out of the water and dropped on the mud. A second Great Black-backed was showing interest, but the 'owner' was having none of it and started a series of aggressive stances. The teal tried to get away, flapping painfully over the mud, but, waterlogged and muddied, it was soon pinned down and pushed head first into the mud, then flipped over- and the feeding began.

Some plucking, mostly stabbing with, by my count, eight tearing actions during a fifteen-minute period. Fifteen minutes during which the Teal continued to struggle intermittently. It was being eaten alive.

At such a time I'm glad Great Black-backed Gulls are in short order around the estuary.

Off the shelves

Following my recent pelagic post, just how deep is the deep water in the Medway?

The deepest waters are at the mouth; to the east of the Isle of Grain, the aptly named Sheerness Harbour Reach (starting in the north-east corner of the picture below) is 21 metres deep in places. That's 21 metres below the chart datum low water mark, which equates to the lowest astronomical tide. So, 21 metres is the minimum depth you'll encounter; on the highest tides you'd have a water depth of a little under 28 metres, give or take a choppy wave/trough. That would sort out most diving birds save the auks. To the south of Grain, Saltpan Reach runs for most of its length at around 13 metres deep.

At the eastern end of Saltpan Reach the deep water navigation channel, marked by the familiar red and green buoys, shallows out at seven metres, with just an incredibly narrow eleven metre channel (marked in blue on the map). To the north of this channel lays the Stoke Shelf, with a depth of just some three and a half metres below the chart datum low water mark, the similarly shallow Stoke Shoal just to the south and west (yellow circles).

South and east of the eleven metre channel is the extensive Sharpness Shelf, just two to four metres in places.

Small wonder the local tugs are kept busy piloting the large Liquefied Natural Gas tankers. The main water body alongside port facilities is dredged routinely to a depth of around 15 metres for these tankers and container ships, but for much of the southern edge the deep water lays some distance out from the shore.

No wonder the birding is hard. How important is a deep water channel for the birds? Feeding? This is a large open area of water where prey can be widespread. There is a more important navigation theory. Most seabirds can easily detect such channels, and stick over them. Theoretically, any seabird silly enough to take the dog-leg into the Medway from the Greater Thames will stay closer to the northern shore- and to date my own observations have shown this to often be the case, especially with Skuas. (This is a well known phenomenon on the Thames- the Channel runs close to the Essex shore and they get close views- but lousy lighting. Kent birders, with the sun behind them, get distant but clear views.)

The next interesting question is whether that narrow, dog-leg eleven metre deep channel at the end of Saltpan Reach is so small as to deter some birds from venturing further up estuary.

The shallower channel opens again to become Kethole Reach, running down to just south of Oakham island. The maximum depth has now dropped to seven metres. Often storm-blown seabirds just circle Kethole, especially when poor weather obscures exit routes. They either
 - (i) head back out past Grain,
 - (ii) gain height and go overland (seabirds often to the Thames, gulls and terns often south over the Medway towns), or
 - (iii) risk following the main channel further west (especially during high water).

Seabirds really don't seem to like the inner estuary. The outer estuary may be poor for seawatching, but the inner is much the poorer in comparison.

This analogy works for transiting sea duck too- by comparison, the mouth of Stangate Creek, a favoured hang-out for sea duck, is some 13 metres deep. If birds settle and take up residence, this rule goes out the window- they settle down around the best feeding areas.

I've also had idle thoughts about whether this puts some waders off routine crossings. One of the things I have noticed over last four years is that waders do not cross the main water body with any regularity; narfsiders roost on the north, sarfsiders the south.

I haven't often seen birds switching between the northern Stoke Saltings and the island complex. If they do, they more often than not switch indirectly moving about covering mud flats in the shallower parts of the estuary and using the central  mudflats such as Bishop Ooze as their stop-off crossing point. Obviously this is probably not a direct choice, the birds just make the most of available feeding time. Perusing W.G.Hale's 'New Naturalists' volume 'Waders', there are maps of wader flightlines around Morecambe/Ribble/Dee that, for the main, do similar.

But rules get broken, and yesterday was one such day when you could see waders crossing the deep water channel direct- over that narrowest point.

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First light, Queenborough, tide on the rise, already covered. Knot have been building in numbers the past couple of weeks, bang on schedule. On Deadman's Island a small group were trying to sit out the rise at Swale Ness. With the Oystercatchers occupying the drier heights, they were eventually pushed off, first south into the Swale, to West Point for a short while before turning round and out to head for Deadman's northern beaches.

In the distance, more Knot wheeled up off Stoke Saltings. With plenty of roost sites on offer there, I expected them to circle and land, but they set out south-east over Stoke Ooze. Over the next half hour another three flocks, all made for the south side. All went shortest route, shallowest water, to congregate on a dry part of the old seawall on Burntwick (blue flightlines).

These Knot may well have overflown the shelves by happy coincidence to reach a safe roost, but the Stoke Avocets went further. Narfside Avocets normally keep themselves to themselves, usually only commuting to and from Oakham, especially on higher tides. I had never seen them cross the deep water channel in four years (and I had been looking), but today they came south. They kept on a straight line over the Sharpness Shelf to turn hard south down Stangate Creek, lost to sight (but perhaps going to join the main southern roost in Funton?) These Avocets also did not cross as one flock, but three, spread out over a 40 minute spell, all on that same flightline (yellow), It was interesting to note how they stayed close to the Burntwick shoreline. They could have saved themselves some flight time by going high overland, or have entered mid-Creek to avoid potential dangers (they are not to know the wildfowlers wouldn't be aiming at them). Essentially they took shallow water for much of the route.

I was uncertain as to why any had crossed in the first place. It was not a particularly high tide, nor too strong a wind. The movement did not happen until after their original high tide roosts had settled, so it might have simply been down to disturbance; wildfowlers perhaps, or just the slow maneuvering of that oil tanker and attendant tugs close by Elphinstone Point?

Whatever the reason, all I know is I really want to watch it happen again.

Rise of the Planet of the Geese

"Never believe what you read on the internet- and yup, that includes my blog."

My tongue-in-cheek response to a birder at Motney. We'd been watching one of the Canada x Greylag hybrids and they started going on about 'hybrid swarms' and growing threats to wild geese species. It turned out they'd read about it in a chat group just this morning. This isn't the post I'd planned for today, but a good opportunity to check my understanding. Because I'm no scientist, but...

Haldane's Rule - if in a species hybrid only one sex is inviable (or sterile) that sex is more likely to be the heterogametic sex.

Whaa? Well, ducks and geese have a long history of interbreeding. Why aren't we overrun with hybrids already?

Studies have already proven that cross-breeding is much more common than we suspect in birds, but there is a weakness in female hybrid offspring that halts proceedings. It isn't that we're overlooking female hybrids, there just simply anywhere near as many out there. This lack of hybrid fitness halts hybrid speciation. Haldane's rule says that (for several science-y type reasons) in certain hybrid types one sex will be always much less successful than the other- the heterogametic sex, the one which has sex chromosomes that differ in morphology which result in two different kinds of gamete- in mammals, that's the male and in birds, that's the female.

A hybrid swarm is slightly different from a new hybrid species- it is a viable mixed population that survives through generations- and geese really don't without any addition of new stock. We can see so many hybrids because they survive through a generation or two, so individuals can be about for quite a period of our own birding careers. I reminded him of longevity in geese- they do reach their mid-twenties. And our feral populations will keep adding a few more hybrids. That mixed-up goose we'd been admiring might be about here for years to come. But such birds will be nearly all male, and not about to take over any time soon.

They then said they'd also read there were concerns over our hybrids going north and infecting populations there.

My reply included why are there so few subspecies in ducks and geese- in subspecies, birds from one (say, Nearctic) population do picked up by another population (say Palearctic) on the wintering grounds and do travel and interbreed- but genetics then deal with them over time and they, for the main, remain global, monotypic species.

Now those successful pick-ups would be happening from other migratory populations. I pointed out most migratory tendencies are genetic- so any mucky Medway hybrid was still more likely to think really not worth going all that way north just for a few weeks of nesting fun with an exotic bird, much easier to stay at home with their cousin...

I left them still wholly unconvinced, still fearing some sort of imminent rising up of the Heinz 57 variety. Thank goodness we hadn't been down the Strand having this conversation- the local Sheldwot really would have given them the heebie-jeebies...

Raving about 'ranting

Say to a birder 'what's a pelagic?' and you'll get a reply along the lines of 'a boat trip out to sea, to search for seabirds'.

Say to a birder 'what's the pelagic?' and quite a few will be hard-pressed to answer.

They might make a stab at ocean waters or similar (the ancient Greek word, pélagos, meant 'open sea') but technically the pelagic zone is something that occurs in oceans, in estuaries, even in lakes. It is the name for the distinct ecological region formed within any column of water that sits away from shore, and above the floor (the latter being the benthic zone, the ecological region at the bottom of a water body which includes sediment and sub-surface layers).

All of which came in useful when I was thinking about the number of Cormorants vs the paucity of Shags on the Medway. Uber-simplistically, the favoured diet of the former consists mainly of benthic fish species, whereas the latter tend to go for the more pelagic fish species.

Part of why there are just a handful of Shag records each winter as against a jettyload of Cormorants.

Some of you will want to look away now; from this point on the post is purely about Cormorants, in particular their feeding behaviour, their loafing areas and their roosts. And their numbers- what is a jettyload?

Feeding

Cormorants are such a successful feeder they only need spend an hour or two a day hunting and can spend the rest of the time lounging around. They tend to get feeding out the way early as well. Many birds leave the Medway to fish elsewhere; in first hour after dawn good counts can be obtained from Queenborough as birds depart out into the greater Thames. At the same time anywhere along the southern stretch an odd bird or three might well be heading inland to feed and several also make their way into the tidal river via Chatham.

Some feed in my stretch, the southern Medway estuary. The texts state they do not often hunt cooperatively, but as I started watching closely I thought they they did it quite often. It took me a little while to work out what was actually happening.

Watch Bartlett and South Yantlet Creeks on a dropping tide in the morning, and there is a good chance you will spot one of these 'feeding flocks'. Each usually around 10- 50 strong (but up to 60 recorded), they raft together and several will be diving together- fish have become concentrated in the creeks on the retreating tide and these birds follow them out.

But watch more closely, and the birds do not arrive as a flock; sometimes in handfuls certainly, but numbers usually build. Nor do they hunt cooperatively, by taking turns in a rolling formation with birds at the rear overflying to take a go at the front- it is simply a melee- nothing frantic, simply each to their own. They are individuals coming together for the food, nothing else.

Loafing or roosting?

Cormorants are diurnal. They migrate during the day, they feed during the day. They need a safe night roost. The 'roosts' we see during the day are loafing areas- haul out spots for the well fed. A place to get rid of the wet as well; Cormorant feathers soak up water to help overcome buoyancy issues, and need time to dry. These loafing sites are deserted at night for the safe roosts. (Logically, in winter most loafing sites will be under water for part of the tidal cycle.)

Loafing spots can be as simple as a marker tower (Pinup Reach off Copperhouse is a good example), discreet as a shallow sandbank (Bartlett, Bishop, Sharpness- tail feathers dry better on sand than wet mud), as obvious as a wreck (the caisson off of Motney) or as straightforward as the actual roost site.

There are two main roosts on the estuary, both viewable distantly from the southern shore. Technically, they are both north shore sites, but they are as easy to count from over here as over there- so it seemed a shame not to(!)

~ Bee Ness Jetty

In the ornithological literature you will find Oakham Jetty, Kingsnorth Jetty and Bees Ness Jetty all listed as roost sites. They refer to the same thing- Bee Ness Jetty. Anyone interested in a potted history of what was, at just over 2.5km, Britain's longest jetty can read about it here. The jetty was abandoned after the site closed in 1977 and so became a safe roost, especially after sizeable sections collapsed, or were removed for safety reasons.

The present roost (shown in red) is on a distant section out over Bee Ness itself.

~ Grain Tunnels

At first glance, this structure is often dismissed as a derelict pier, but actually sits above the twin cable tunnels linking Grain with Chetney (if anyone knows the exact purpose, I would love to know) and was never linked to the shore. The tunnels are 1.7 km in length, and 2.8 metres in diameter- workers do access them, at that size I certainly wouldn't like to(!) Aerial views courtesy of Google Earth also confirm the 'jetty' to have two large open spaces- all in all a perfect, safe remote roost site.

It seems this has been overlooked in literature, perhaps because this part of Grain is often overlooked by birders; most published counts for Medway have been simply for Bee Ness.

Birds from both roosts will disperse in all directions. Watch them often enough and you start to realise whilst more tend stay in the Medway when waters are low and feeding is easy, most will still head out into the Thames estuary to the north and east of Sheerness; Cormorants are known to travel routinely up to 15 kilometres to feed- so this sort of distance is just a short daily commute for the Medway's birds.

Numbers

Historic counts reflect the increase in overall numbers seen since Cormorants started breeding inland in the south-east of England during the 1980s, with the increase in early autumn numbers being down to dispersing young. Before that, peaks were always in winter, and were British birds, mainly Welsh, also Scottish and north of England. Wales might seem an odd source at first, but Cormorants are not routinely pelagic- they like to stay in sight of land, so overland dispersal is just as routine as coastal.

Kent has rather more overseas ringing reports than neighbouring Essex and Sussex, which makes sense and hints towards the possible small but regular arrival of the subspecies sinensis from increasing numbers breeding on the near continent in the 1980s being the source of the new colonies.

Put simply, sinensis favours fresher water and breeds inland in trees, whilst carbo favours saltwater and the coast. I never really bother to assign to race here. They are usually way too far out to play with assessing gular patch angles (which in any event overlap slightly) and, besides, work on brood DNA in the new inland colonies has shown carbo to have got themselves caught up in small numbers. They just go down as Cormorant.

You can, however, record fairly easily the slow drop in numbers of young as they continue to disperse, and are replaced by more adults arriving to winter. Or seemingly winter. The term in 'BWP' is individual nomadism. Birds can and will continue to change sites during the winter. Some years see more birds than others, which is down to prey availability. Cormorants are fickle.

There has been a small collapse in numbers during the present decade, mainly down to small collapses out along that final kilometre of the Bee Ness Jetty. The safe roost capacity has been shrinking. It will be interesting to see what happens in the next few years. Historically, a jettyload was up to around 350 birds, 400 tops. During the past four years my roost counts (dusk/dawn) have never really moved much above the 200 mark, and the favoured stretch has been packed. (Grain has remained steady at around the 50 to 80 mark.)

If the crumbling continues, could they switch elsewhere? Probably not that easily. One or two alaready loaf on Kingsnorth Jetty, but that is usually atop the old lamp posts- Kingsnorth has been all too regularly disturbed by security patrols in the past. The patrols could be tolerated by gulls, which would rise and return when the danger was gone, so the handrails beyond Oakham island were claimed as a regular roost for Common Gulls when the power station was in operation.

Counting

Being diurnal, roosting Cormorants tend to congregate in number as dusk begins, and only a few stragglers leave returning until the final fifteen minutes before sunset. They do seem to start to leave at the first traces of dawn, and can be missed- a morning count following an evening add-up have tends to be down by about 10-20%.

Counts of the roost during other times of the day can be misleading. Counts in discreet areas of the estuary can seem not as useful at first glance- but do confirm feeding areas and can be hugely entertaining. In early November this year, on an uncovering tide just after dawn, I watched a number of Cormorants leaving the Bee Ness Jetty roost and ending up on the edge of Bartlett Spit as it began to uncover.

My notebook read as follows:

0 @ 06:50
14 @ 06:55- flew in together to land on mudflat edge.
19 @ 07:05- a further 5 flight in
32 @ 07:10- further arrivals take group to 32. Most are near to each other in loose gathering, one c. 50 metres away.
32 @ 07:23- first five enter water, rest stay on mudflat. Fishing commences.
1 @ 07:27- female Marsh Harrier crosses estuary from Bayford, keeps some distance from Cormorants over Bishop Ooze. Panicking waders cause all Cormorants (bar the individual) to take to air and drop into South Yantlet Creek out of sight behind Nor/Friars Saltings.
47 @ 07:30- 40, then a 3 and a 4, drift back out (clearly more had been loafing out of sight), none are feeding.
0 @ 07:31- all back into South Yantlet Creek as Marsh Harrier reappears, with a Buzzard for company.
16 @ 07:33- 14 and 2 back out, fishing.
34 @ 07:39- 27 swim back and haul out, another 5 remain in creek, 3 individuals, 2 close together, starting to dive. 2 more fly in onto flat.
34 @ 07:41- female Marsh Harrier passes back along South Yantlet Creek- 1 Cormorant takes flight from water and is harried for a short distance before MH gives up.
43 @ 07:42- 9 more swim in from behind Friars, to haul out some 60 metres west of main group.
42 @ 07:54- 1 from main group takes off and heads inland.
42 @ 08:02- all but two enter water, many starting to dive.
56 @ 08:04- the Marsh Harrier returns and 39  birds leave water for mudflat. At same time numbers on water are boosted by more birds arriving from behind Friars- 17 now swimming together.
56 @08:05- Marsh Harrier flights at group, all bar 12 enter the water and start to head behind Friars.
0 @ 08:07- remainder enter water and disappear behind Friars- waders also panic and flight. Marsh Harrier now seen to have claimed fish, and drops onto flat to eat. The Cormorants do not return.


All good stuff, but if I had simply counted and moved on I could have had any figure between 0 and 56 down as present:

Of course, each total would have been right for that exact minute, but it wouldn't have told the story.

Why, if you can spare the time, always worth staying and watching a spot for as long as you possibly can. I know most of us like to use the term 'birder' nowadays, but being a 'birdwatcher' can still be fun.

At the moment I have one burning Cormorant-related question. When you scan Bee Ness, it appears that birds are sometimes in pairs. Years ago it was thought that behaviour might be pairing up prior to returning to the breeding grounds, but that was dismissed in more recent texts- display and pair formation happens back at the colonies. So what is this apparent pairing all about? Answers on an electronic postcard, please...

A picture post, from December 2013

Otterham, on the full

Rock Pipit

Motney reed beds

The wildfowlers' walk, Copperhouse

Brent, Twinney

Motney sunset

High tide, Motney

Avocets settling at Motney

Curlew roost on Motney Hill

Chaffinch pre-roost assembly, Berengrave

Motney reed bed

Disturbing conversations #1: the runner

For four years I've been asking questions, most politely, of the public about their activities up and down the shore. So as to get a feel for other users' viewpoints, so as to better understand the levels of disturbance waders and wildfowl put up with here. Obviously properly conducted surveys, such as I've mentioned before, are the correct way of doing research- but, to date I've not yet got into any 'robust debate', and I genuinely find I learn something.

Today's chat went something like this:

(Me, from private land, with permission): "Hi, hope you wouldn't mind me asking a question or two.." (sweet blah blah blahs, then cutting to the chase) "do you know the saltings you're just about to run out onto are an RSPB reserve with no public access?"

"Ummmm, y... no. There's no signs." (I agree) "No, putting up a sign wouldn't stop me, I've run them for 30 years... Yes, I do run here on all sorts of tides- that's the best bit, when the birds are here; I enjoy seeing them fly up and away... I don't get to see that happen as often as I'd like as tide's not always in, but it's great when I do... This sort of spot can't just be left to the birds, we deserve pretty places to run... I used to run on the other side of the creek, but that sea wall is so pot-holed now, they ought to lay a nice running surface... What it needs is signs back in the Country Park... And hides there for you birdwatchers to go in out of everyone's way... And an education centre- we need educating..."

(I nodded in agreement to the last statement, and we parted with a handshake and a smile. Each still on their original route.)

A ring from middle estuary: #1306348

Although I now restrict myself to the southern shore I trained as a ringer under my good friend Bill Jones out on Oakham Island, which is frustratingly mid-estuary, just north of the main channel. I hope no-one objects to my publishing an occasional map from some of his ringing recoveries over the years here on this blog for interest

Grey Plover Ring no. 1306348
Ringed as an adult female, 26th May 1996, Castricum, Nord-Holland, The Netherlands.
Retrapped: 8th September 2002, Oakham.
Found 2296 days after ringing, 303 kilometres south-west of ringing site.

This time I haven't joined the two sites with a line. With the number of years between ringing and recapture, the fact the bird was an adult when ringed, and ringing was en route to breeding grounds and recapture en route for winter, the chances are that in any statistical analysis of all records, this would be weighted towards choosing a route close to the continental mainland on the way back racing back from a wintering ground much further south. This was the seventh inbound trip later, so one would hope she knew what she was doing. The autumn choice of route is influenced by the need to find somewhere to undertake a partial moult of flight feathers safely- stopping for a short period on the Medway had probably been a good choice for this bird down the years.

This sort of record always has me wondering if these birds ever take a short cut overland, say, from the Medway to the south coast. A good probability. After all, GPS studies on other migration routes have confirmed them not to be deterred by a little bit of ground, say, most of mainland Russia and China...

Summers-Grey

In one meeting recently I was asked a question, as an aside, about Grey Plovers on the Medway. Was it true they roost over on the Swale? The question came during a chat on wader declines in the estuary. My answer was short, but deserving of a much fuller explanation so, to keep a promise...

The Swale

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Decline and fall

When I started my estuary counts I took my own year zero of 2013. Prior to that mid-nineties had seen published early winter peaks circling the 2,500 mark, peaking in January at around the 4-5,000 mark. After that time the numbers reported crashed, with the average winter count for the ten full winters to year zero scraping 660 for Nov-Jan- if correct, up to about an 87% crash. And perhaps knocking nearly 10% of the UK population off if they had disappeared completely (some 43,000 in 08/09, per BTO website).

Of course, if the figures were wrong, then so too could be this trend. That, as a simple birder, would be my incentive for getting out and enjoying the Medway. The evidence of a continuing fall via WEBs results remains a worry, but comes with a caveat that counts here are often incomplete, and un-coordinated. Could this be part of the problem?

Focusing in more closely, the BTO produced a report in 2005 in response to the drop in Grey Plovers, and several other species at the same time. Statistical testing suggested the decline in numbers from a level of International Importance had been mirrored somewhat in both the Thames and the Swale.

Big declines in North Kent as a whole. What about next door? Not seen in Essex, not as big in Sussex.

Essex totals had remained on the increase from the mid-80s, doubling to a five year average of 15- 16,000 between 1995 and 2004, with a peak of over 22,000 in 2001.

Next door, the latest Sussex Atlas says a steady increase in the 70s and 80s, but a slow decline thereafter, by only about 25% and intriguingly their best site, Pagham, remaining steady.

Concerns over these low numbers continue to this day (I was pleased to hear about ongoing work on the populations of prey items in Medway’s benthic zone) but in 2013 I was focused on published numbers and seeing for myself if current numbers were indeed correct.

-----


Comings and goings

A behavioral case study from Motney Hill. (Okay, I admit it, I have ideas above my station- I simply read the behaviour sections in 'Birds of the Western Palearctic' and 'The Tundra Plovers' amongst others, and tried to see for myself...)

A marked Grey Plover was in situ for a couple of winters, allowing me to track regularly. No colour-ring for this bird, but a stand out ‘summer plumage’ appearance. Yes, that’s the wrong terminology and a subject for another time; in short appearance is due to hormones out of whack rather than retention of old feathers or growth of a set at the wrong time. I nicknamed the bird ‘Summers’, so the terminology stuck. (Actually I used Summers-Grey, for all you X-Men geeks out there.)

Summers wouldn’t arrive until November, in line with many of true wintering birds. These are then usually site-faithful, with just a small amount of hard weather movement recorded.

The fun was Summers was what I term an alpha, setting up and retaining a nice little territory close to Motney Hill Saltings. A long, thin territory, based around a shallow gutway, which it defended from other Grey Plovers. Low tide, Summers would be mainly out in the furthest stretch, on the covering, much closer. A long, thin territory with a moving core, easily mapped.

Feeding is primarily by sight, mainly surface-picking/-probing, so having a clearly defined productive stretch to defend from incomers appears a good survival technique. Many Grey Plovers do the same. Her neighbours did likewise, of course I could only presume to be the same birds, Dave, Dave and Dave (for all you Trigger fans). Occasionally one of the Daves would get a little too close and there would be a bit of parading, a bit of running about and calling, but very little actual aggression (why waste energy fighting?).

As the tide rose, the territory shrank until Summers would be up against the edge of the saltings. Now, if you have a territory, and there is safe roosting close by, why fly any distance to a roost? Summers would simply retreat up into the saltings, sometimes joined closely by Dave, sometimes by Dave and Dave, sometimes all the Daves (no feeding to protect, why fight?)

February saw Summers disappear around the same time as the other two regular Summers present (this interesting plumage type was not as rare as I'd originally thought) one from Funton, one from Copperhouse.

The Copperhouse bird tells the rest of the Grey Plover story. Texts hint at only about a third of studied populations being territorial. Large open flats are less easily marked out, so territories are harder to define and defended. Here, loose associations build up which I called the Betas. Small flocks (usually up to about 30/40**) of non-territorial birds would drift about a favourite route of flats.

**Actually, I’m amazed how many times my counts come out as ‘38’. Getting to the point where a group flies goes past and I automatically start writing 38... The texts say usually up to 30, but 38 is the magic number here on the Medway.

Are my terms Alpha and Beta right? Well, most of the recognisable juveniles are in the loose flocks, seemingly rarely holding a territory. An advantage to a territory is a bird with a creek or runnel to call home with a cosy windbreak to hunker down in. It sort of pointed to a dominant strategy to me at first, but I had to remind myself the Copperhouse Summers bird was non-territorial, a Beta (pictured above, with chums at roost) and doing alright. The texts hint at birds adopting one or other strategy for life. Loose non-territorial flocks obviously do work.

So, the birds on the Medway appear to behave much as the birds elsewhere. A question for me now was I could fairly easily count territorial birds on the low tide. Were these local territorial numbers going to come out at around the one in three of the population mark? I doubted it, as every estuary is different, but it would be fun to find a figure.


Roosting patterns

Tides bring the loose flocks into close association with several Alphas as the waters cover. Often a flock just 'appears'. Again, why go that far to roost when feeding is good? Sometimes, yes, several beta feeding flocks congeal into a larger roost flock (especially for higher tides) and you had the idea of the species being a flocking bird, but that is not the whole story.

Take birds around Rainham. As well as trying to roost on Motney and Rainham Saltings on slacker tides, they will often move out to Friars and the old walls of Nor, as well as Darnet. On low tide, these loose flocks might be found on the adjacent mudflats mid-channel. They have a circuit, and whether you pick most of them all up depends on the tidal state.

Down estuary, Lower Halstow sees an assembly on the south side of Millfordhope saltings, moving onto Greenborough by Millfordhope Creek, whilst Funton birds come together close to Barksore or on the Bedlams saltings. Higher tides they move onto the seawalls, a few times over them.  At this point worth remembering they can feed inland at night. From some nocturnal wanderings around Otterham Creek the Greys based there do a lot of territorial calling on a dark rise, before switching over onto grassland for the odd earthworm or six.

Grey Plover ringed inside the seawall, 2016 - note nictitating membrane, the 'third eyelid')

In daylight, close to the Swale, I have seen small numbers pop over the Bedlams seawall. And I have seen them drop back. But never any determined flight at height, suggestive  a longish flight switching water bodies.

I also think this because, when watching at Queenborough, Grey Plovers coming into the Medway off the Roas and Minster Flats always do so over water. Always at a bit of height. I have never had them doing the Curlew trick of routinely commuting overland south of Sheerness from the Minster flats. There is no real rhyme or reason to Grey Plover flights into the Medway. The Thames, Swale and Medway just come together as one body here, the birds don’t know our political boundaries. Sometimes they just feel safer on Deadmans/ Burntwick.

Very, very few of these birds head down the Swale. If they do go past me, they stop at Shepherd's Creek behind Deadmans. The Swale does a narrow s-bend past there, making for a convoluted route to any safe roost further on.

All this is not to say, from time to time, that Grey Plovers do not enter the Swale. Someone may have seen it. It just doesn’t isn't logical for it to be a routine behaviour.

------

Number crunching

A conservative estimate of easily countable territorials from the southern sea wall, copmbined with flocks operating between Upnor Reach and Deadman’s reaches the 400 mark fairly easily. And as I did not discover the 30% figure for a while, I was pleased that I hadn't been influenced by it. My estimations came out at about a 40% territorial take up, surely a reasonable margin of difference.

The published WeBS counts of late have not reflected these sort of numbers:

10/11 - 641
11/12 - 373
12/13 - 154
13/14  - 72
14/15 – 198
5 year average 288.
The last Low Tide Count in 13/14 came in at just 120.

And these are, of course, for the whole of the Medway Estuary, not just my southern shore.

The WeBS counts are incomplete. They should take place on high tide when Grey Plover can be tucked up in small groups among the saltings at high tide- it would be hard to count them all at the best of times. Low tide and many of the Beta flocks would be out mid-Channel, where, even with 'scopes hard to pick up unless flighting.


What next?

As far as WeBS is concerned, the local BTO Regional Rep, Geoff Orton, has been calling for more volunteers this autumn @gronto . The more the merrier. When I last spoke with him, the pipedream of a full crew plus reserves to ensure a complete co-ordinated count remained just that. Help is needed. Low Tide Counts, usually every five years or so, were the same last time out.

If you are out along the south Medway and you provide records to the various bodies, do send in and try to refine the site details. Include in your notes whether in flocks, in flight. This will allow more detailed analysis.

If anyone wants, have a go at proving/disprove my figures- here’s how to do it. Gillingham/Rainham side, count the various bays separately from low tide onward on a windless day. Count any groups present (all of which will be 38), then add any further groups arriving from mid-estuary (Bartlett, Bishops, South Yantlet, Middle).

It will start to make sense.

To the east, Ham Ooze is a little more perplexing, but most groups just move into the Greenborough complex, a few might continue into Funton/Halstow. Check the distant edge of Millfordhope where many pre-assemble.

For the far east, 'scope Blackstakes and Queenborough Spit well before the 2.5 metre, then hold out until full tide for stragglers coming in from the Thames.

I’m slightly tongue-in-cheek as I say that, I know I'm one of a small few willing to dedicate so much time on such things, and can’t really expect others to do likewise- but if you do send records in, all of this helps show why it’s worth recording which creek and state of tide- and that your general counts, however small, are worthwhile.


The rest of the year

To complete the Grey Plover year, small flocks do occur in Spring but the bigger numbers are in autumn.

Most winterers leave February into March, and any late March/April counts are transients, often only staying a few days.

Return passage can be encountered from July onward. Present numbers probably best mirror the early-eighties results- an August arrival, mid-estuary, of a flock of 500 or more in summer finery is always a red-letter day. Typically, some will only stay a few days then move, others will spread out and then carry out part of the moult of their flight feathers over several weeks. There is then a gradual drop-off before the November winterers pour in.

This might hint at a reason for the drop in recorded numbers. Typically, birders do not routinely count anymore. And there are fewer birders straying away from the honeypots in North Kent. Always a red-letter day when I bump into a birder in late summer now.

That short window of midsummer is murder, as you are usually tracking down just a single flock of young birds seeing out their first year well away from breeding grounds (yup, 38 again). They will spend a few days on one creek only to then perhaps pop up mid-estuary on Ham Ooze before venturing into another part of the estuary for a short period. Do they ever cross the main channel north? Just once to date, so I can’t yet say this is a regular occurrence.

All in all, there is still an awful lot to find out about the birds here. But from what I’d seen so far- did the Medway Grey Plovers roost regularly over in the Swale? That short answer had been 'nah'.