The Medway Gulleries

(Please note this page is a work-in-progress. Additions will be notified via the blog as/when they occur.)

The purpose of this page is help show birders their own counts can help providing an overview of the breeding seabirds on the Medway. It first sets out the best ways to count, then explains how to take on counts each of the islands. I hope one or two of you might find it useful ad have a go yourselves.

Please note I have not gone into full details of species involved. For the main part I have simply written as if discussing the most numerous breeder, Black-headed Gull.

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When I arrived back in North Kent, I set some targets and some limitations for myself. While there are regular boat trips available to view the islands, but I had decided I wanted to bird everything from the shore. This was always going to make things hard when it came to the islands.

The south Medway islands have long held good numbers of breeding waders, and for several decades now, gulls. Anyone who knows me knows gulls have never been high among my favourites, but I was going to have to bite the bullet- I simply couldn't ignore them now. Several landowners along the shore also have stakes/interests in some of the islands, and were keen for any estimates I might be able to provide them.

I was already aware the gulleries should 'do-able' from shore, using certain of the methods listed in the excellent 'Bird Monitoring Methods' (Gilbert, Gibbons and Evans, RSPB 1998). There are two goals to aim for- population size and productivity.

Population size. Some methods were completely out- transects and similar. However keen you might be to land, Gilbert makes clear these methods involve considerable disturbance. In the past, many surveys have been done by landing, but the Islands continue to erode and sea levels rise. In the main, only a small percentage of any island avoids inundation, and nest sites are limited, If you can survey without landing, you really should.

Counts from vantage points- the methodology says minimum one visit (but preferably more, separated by a few days), in late May to early June. You should be looking to obtain a maximum number of occupied nests (AONs) or apparently occupied territories (AOTs).

Counts from photographs- another method for the more inaccessible breeding colony. From the water might be an ideal, but my strict limitation was in place. Thankfully, several areas can still be photographed. Over the high tide is perfect, much of the saltings are under and you can pick out the sitting birds quite easily. I combine with the VP counts, if only because my camera equipment is basic- that does the specks, the 'scope i.ds the specks.

Flush counts- said to be a last resort method, only if others cannot be done. Suitable for small colonies where all can be flushed at once. Translate that to the everyday Medway? Once you know the islands' names and boundaries, and you have an idea of of where on each those various satellite colonies are, you really can rely on another river user flushing the birds for you at some time or another. You might also have a 'dread' occur, where a colony all lifts off quietly together for no apparent reason. They happen more often earlier in the season when you'll have non-breeders as well, but when happens at right time, a dread does give yet another confirmatory figure.

Finally, the tides help as well. The spring tides during the breeding season have gulls just about hanging on over several sites where the nests can tolerate a little flooding.

At the start of last year, 2015, I plotted the 'bird tides'to an excel spreadsheet from one of the many tide forecast websites. This was the name given by the 19th century Medway fishermen to period of lower spring tides between the quarterly high springs that mark the beginning/end of the breeding season. They said the birds seemed to know when to stop all their gullery posturing and start nesting in earnest.

With this in the notebook, I had no excuse for not counting at the most appropriate times.

Byusing this combination of methods, I aim to be able to not only get a good estimation for several of the islands, but also to have a narrative of the season. An example was the early May surge in 2015 which washed out several south-westerly nests; as soon as this happened I plotted the average relaying periods to see if time still available before the high spring:

Continuing this way throughout the breeding season actual made the whole of the exercise much less of a chore (at one point I even began to worry I was coming to like gulls!).

Productivity.

After cracking population, I still had a bit of a nightmare. 'Chick mobility' is not your friend at great distances. Not only are they pains pre-fledging, but they may not hang around estuary very long post-fledging; fledged birds from elsewhere soon turn up as well. You could hope local fledglings might form into small groups for a short while, but miss a day on the river and you could miss it. Essentially good productivity data comes down to ringing effort, and while I have been asked to sonsider ringing one or two colonies I personally have no intention of obtaining a Schedule one licence; there is enough disturbance happening out there already.

What I did have is the ability to carry out mapped nest observations. Numbers of (i) large chicks and (ii) small chicks, plus number of incubating adults seen in the days prior to first chicks fledging. This fitted with the daily walks nicely, and weaved into the narrative. This could not be done effectively at the extreme end of the distance scale, e.g. Burntwick and parts of Greenborough, but food-carrying parents could be counted from several observation points.

In the first year back I concerned myself with how 'bad' my data might be. My own controls and checks started as simply counting often and photographing to re-count the specks on computer screen. I soon worked out natural variability due to such things as time of day, height of tide, etc, and was fairly happy with my percentage spread. I then spotted a gift of a check, good old Google Earth. Though now not as a good a resolution on the historic imagery, at the time I sussed it their mapping was using images from August 2013, and you could see the old nestsites in the colonies quite well. Better yet, when I went to the historic imagery button, up came July and the white specks were back. This was fortuitous- the next most recent breeding imagery was from back in 2007, but then the most up to date mapping came online and was April 2015. I'd started counting from the time of the first returning birds in February, and found my counts for that week of April to be close to numbers in the pictures- much of the Island complex gull population can be surveyed from shore.

Just as I try to cover the wintering waders every ten days, I try to visit all the viewpoints once every ten day period during the breeding season as a minimum. If you can put up with the heat haze and if you can forget about the lack of close-up views, spending a short while getting an estimation at any of the following sites becomes addictive, and any counts you make will add to the databases. If you are on the seawall between early May and late July, you might like to give it a try.

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The Island colonies:


1) Copperhouse Marshes

This could have become history in the three years I have been watching. The closest colonies to shore, just 200 metres from the nearest public footpath, Copperhouse is low lying and suffers badly on spring tides, especially in combination with low pressure systems. 2014 had bad productivity, but in 2015 saw some start to display in early April the early displayers all deserted within a couple of weeks (see Nor, below). It is a little early to say if they have given up on Copperhouse for good, but with rising tides they only can have few productive years left.


2) Nor Marsh

The majority of the nesting birds are on the bare sea walls on the south and east of the Marsh, or on the small raised area in the south-east corner just behind the walls. These are scoped easily from Horrid Hill, a distance of some 600 metres. The sea wall was breached in the storms of 1953, and since then much of the Marsh has been washed away- little remains above water on the higher tides now.

2015 saw all of the birds displaying from the south-west corner to the southern tip desert this regularly used stretch. This is essentially the length of wall that can be walked east as far as the first small breach, and which at its western end joins the causeway, a walkable (but highly dangerous) path back over the flats and creeks to the mainland. The causeway is used (legitimately) by wildfowlers to access Friars Saltings, and at other times of the year taken by a few brave bait diggers and crabbers, usually very early in the morning (I have seen them walking out from first light in May). No-one was seen on the causeway at the time the birds desrted, but it was interesting to note they only deserted along the stretch that could be accessed on foot. (RSPB Investigations Unit were informed at the time, and the local birders kept an eye for any further unusual activity.) The remaining birds got a low number of young off; as with other sea wall colonies here, the older stretches are riddled with rats, which are probably the main predator for all the ground nesting birds on the islands.


3) Friars Saltings

The saltings just to the east of Nor Marsh, outside of the obvious sea wall in Nor's google image one. Though a much smaller area than Nor, the suitable areas on the southern tip held pairs of gulls than Nor in the last two years. They can be counted easily from Horrid Hill, some 1.1 kilometres distant. The south-westerly gales dislodged some breeders in 2015 (and the small Common Tern colony gave up the ghost), but more chicks were also fledged from here than from Nor.


4) Bishop Saltings

I couldn't resist leaving out the picture of Bishop as a whole and instead including 'The Seal', from the eastern end. Bishop is the inset in the picture. In fact, once extended westwards, but is now conveniently broken in two by even a neap tide; the western element, which includes Darnett Ness Fort, is much too disturbed for any colony nesting birds, During the summer months it attracts too many overnight campers and day visitors (mainly by canoe and small hovercraft).

Though lacking in raised sea walls, the eastern complex has several suitable areas of higher ground for breeding gulls, and holds impressive numbers each year. The mix of channels help protect many from wave action during the south-westerly gales- only the most westerly groups suffered serious losses in 2015.

Observations from public areas on the south shore are problematic. From Horrid Hill you are scoping at 1.9 kilometres which, with practice, is do-able on the high tides. Nor Marsh is in the way unless you stand on one of the benches (and I always put down a plastic bag if I do to avoid making a mess!). The second photograph in the 'Nor' section was taken this way, and the thin line of gulls at back of shot are a part of the Bishop breeders. Thankfully the birds also rise a lot over the tides. The image above shows foreshortening in action, the 'line' of gulls over their soggy nest site spread out about the length of the yellow line on the inset).

Closest to the far side of the estuary, viewing from the north shore should be possible but, thanks to the Long Reach jetty being in the way, is greatly restricted. The backlighting at 1.9 kilometres is also a pain!


5) Slayhills Saltings and Millfordhope Marsh (west)

At 1.1 kilometres and 900 metres from the public footpath at Shoregate Creek, the seawall colonies are easily viewable by 'scope. Slayhills Marsh can be done from here, but I prefer to count (with Millfordhope east) with Greenborough (see below). Both are prone to suffering from wave action, with a large number of nests lost to strong winds in 2015.


6) Greenborough Marshes and Slayhills Marsh (and Millfordhope east)

Now we are getting dedicated. The Saxon shoreway on Brasser Hill gives you about a fifty metre elevation from which to scan distantly, but the distances are growing. Millfordhope is 2.3 kilometres, Slayhills 3.0 kilometres, and Greenborough between 2.3 and 4.0 kilometres. Sounds horrible, but is relatively easy with (in my case a x30) telescope. A high tide floods much of the low-lying saltings, making it easier to see the complex of seawall and small pockets of higher ground where the colonies sit. 2015 was an average year for this part of the Islands complex, with a small volume of human disturbance noted, and very little over-topping of nests during the highest tides.

7) Burntwick Island (a.k.a., west and centre, Sharpness Saltings, to the east, Sharfleet Saltings) 

If you thought we were dedicated before, now we are getting really dedicated. Certifiably dedicated. 5.3 kilometres from Brasser Hill (there are nearer points, but none open to the public). When you first view from here, you think you are stuck with specks. The two photographs both have the edge of Barksore Marsh, the flooded Slayhills/Greenborough complex in fore- and middle ground before Burntwick (the building is an old barracks which had a nice parade ground in front of it).

However, those Burntwick specks do like to get up and feed, and a few hour's watching here and there soon establishes flight paths from feeding grounds to the south, and the make-up of the various colonies take shape. Although the Island most prone to 'estimation', Burntwick colony estimations did again tied in nicely with Google Earth imagery. In 2015 much of the western end, Sharpness saltings, suffered losses during the high winds in 2015. Sharfleet saltings, although higher ground, took a pounding during two of the storms and lost good numbers of nests down its western half..

8) Deadman's Island

Deadmans lays between 500 and 1,300 metres distant from the seawall at Queenborough Point. Although there are few gulls here, those that are present can be picked out over the high tides. (The metal benches come in handy, please wipe your feet! The fit and able can also try scaling the seawall should they wish risking life and limb.

The other interesting behaviour here is watching Medway seabirds moving to feed in the more open seas of the Greater Thames Estuary. The non-sitting Sandwich Terns routinely flight out in big numbers during the hour around dawn, helping to confirm any estimates of breeding numbers made elsewhere during the incubation period.

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