Birding the southern Medway: Duck Soup

Thursday, 12 January 2017

Duck Soup

Sometimes when I'm out I get asked why I count. The answer is always the same. "I don't count for the number, I count to understand."

Rainham Creek

Why count wildfowl and waders?

Most birders think there's enough counting being done already, that they needn't bother. For an estuary, they often hold faith in WeBS. That sets out to meet three main objectives:

(i) to assess the size of non-breeding waterbird populations in the UK
(ii) to assess trends in their numbers and distribution in the UK
and (iii) to assess the importance of individual UK sites for waterbirds

Even though we are heading out of the EU, many conservationists hope much of existing European Law will be kept in some form, leaving us with something similar to the existing EU Birds Directive and Habitats Directive which require us to identify important wetlands for birds and designate them as protected. It comes with compulsory monitoring to covering breeding, wintering, and migratory populations using the wetland.

Regardless of Brexit, the UK is bound by other international agreements. Also over and above us is the Ramsar Convention on 'Wetlands of International Importance especially as Waterfowl Habitat'. We have also signed up to the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA). Signatories must conserve migratory waterbirds along the entire length of the flyways. Sites of migratory waterbirds to be protected and managed appropriately. So, adequate monitoring is needed for several vital international agreements, and WeBS is suitable for these as well. It is a vital national count.

Although WeBS aims for complete co-ordinated coverage, gaps happen and adjustments have to be calculated via the magic of algorythms and the like. All well and good, but the Medway is an oddity. No other tidal estuary in the UK has such a series of islands as those found here. I'm no statistician, but... local knowledge and interpretation is vital for understanding bird counts here on the Medway.

To illustrate this I want to blog about dabbling duck.

Dabbling ducks- the Anas family

Funton Reach

While counting, there are three main 'needs' to consider from the outset- breeding, feeding and safe roosting. The first we can forget for much of the winter (many duck do pair up on wintering grounds to save time when they arrive at breeding sites), leaving feeding and safe roosting, both straightforward enough to monitor; counts help to understand how and why so many birds stay on the Medway.

In general, loafing requirements are not unique to each type of dabbling duck, but diet and feeding behaviour do have more significant differences between each of the Anas species.

They all use feeding zones and loafing zones, which together form their core areas. Wintering grounds have to have safe core areas. A non-tidal loafing zone on the landward side of the seawall might well allow some duck to remain undisturbed all day, but if members of that same species have to loaf on mudflats then they have to work around the rhythms of the estuary, either moving or riding out the covering tide (and wasting energy by trying not to go with the flow). These problems are usually outweighed by the safe roosting, and for some, the chance to continue to feed if needs be.

So they might have to move a short distance to a safer salting when the tide comes in. They might also have to move again on the higher tides, and the largest spring tides pose their own problems here.

Then throw in the weather- what do birds do when their chosen loafing waters are frozen? Or when rough waters last for several days?

If you think counting with these sorts of things in mind is O.T.T., well we Brits do get off lightly with simple counts. For example, we only get asked to do Low Tide Counts by the BTO every six years, and usually just asked for the numbers of birds. If you look at somewhere like Eire, their count instructions instruct volunteers to go the step further and record numbers as loafing or feeding.

The general mix on the Medway

Working west to east, at the estuary head Chatham has a level of urban development gives no room for landward roosting, so few dabbling duck chose to loaf near the head of the estuary. By Gillingham the mudflats are widening and duck can sit out on the flats some distance from the shore. The first islands are also nearby and a few wildfowl can now loaf in cover on Hoo, or Copperhouse. (The latter goes under on spring tides when the birds make for Nor/Friars.)

Teal in particular favour Copperhouse, which belongs to Kent Wildfowlers and is shot, mostly at the end of the working week, (why midweek counts are usually highest here). Other species tend to float out into South Yantlet Creek and jump the wall into Nor,

They will be joined there by Sharps Green Bay and Rainham Creek duck on the higher tides. Both these sites do have low-lying saltings where the birds may hole up, but if covered by a spring tide, or disturbed, then they will flight out to Nor/Friars. (Nor is an RSPB reserve, but the adjoining Friars is Kent Wildfowlers, and shot routinely). On the highest spring tides Nor and Friars all but disappear; the duck will try to ride out the waves, or flight east.

The Motney peninsula offers some safe loafing for those species that enjoy dense cover, at the point in the reed beds of Southern Water Sewage Plant and along the reedy neck of the peninsula. The more open waters there that attract most duck are within the Kent Wildfowlers conservation area, while the section owned by Medway Council has seen less management and has more scrub encroachment. To the east, Otterham Creek is too narrow to offer safe roosting where the footpath runs alongside, but at low tide duck can loaf on the northern half in relative peace. The private grazing marshes behind the eastern seawall provide both feeding and loafing opportunities, but are working areas, and shot routinely in season.

This land is on the Ham Green peninsula, a large and obvious natural divide to the southern shore of the estuary. Beyond Ham Green, the shoreline is relatively undeveloped, the estuary is at its widest, and the major island complex sits just offshore as an appealing refuge (when not being shot).

So, from the low water mark out in mid estuary most dabbling duck will ride the tide up to south of Burntwick island to float and flight into the Greenborough complex, where they will be joined by birds from closer to shore from around the eastern edge Ham Green peninsula and Twinney/Halstow Creeks. Some might chose the Barksore peninsula, but the islands are more natural and offer many safe area, despite the frequent wildfowling there.

When disturbed from the shore, Funton duck also mainly ignore the ploughed fields on Barksore, instead opting largely for the grassland of the Chetney peninsula.There the many dykes and flashes spread among grazed grassland are much more appealing. Much of Chetney is a game shoot, with most disturbance seen at the week's end and the weekend. The majority of duck disturbed from Chetney will flight towards the islands.

This offers one explanation why WeBS duck totals seem routinely low- land based counters go out on the correct weekend dates when their duck numbers are often low when compared to mid-week dates, being disturbed by more fowling. With the waterborne counters mainly out mid-week, duck numbers around the islands are often lower, as they can loaf in peace closer to their feeding zones.

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Over the next few days a series of six short blogposts will look at the individual ingredients that make up the dabbling Duck Soup. Hopefully something to taste for all- bon appetite mes amis!