From Edinburgh Ringing Group Report 3, 16-19.
Introduction
During the period 1964-66 a series of 4 'lagoons' was built at Musselburgh, by the South of Scotland Electricity Board, in which the waste ash from Cockenzie Power Station could be dumped. The lagoons were formed by building a sea wall of concrete blocks and rubble from the east bank of the River Esk, where it enters the Forth, to Prestongrange. The whole area, of approximately 300 acres, was divided into 4 separate lagoons by 3 walls running between the outer sea wall and the old shoreline. A mixture of water and ash is being pumped from the power station into the lagoons filling them in turn. The east lagoon was completely filled by 1971 and the next lagoon will be filled by 1977 at the latest. The water level in the other 2 lagoons rises and falls in sympathy, but not in phase, with the tides. The level is maximal at the end of a series of spring tides and minimal at the end of a series of neap tides. Early in the history of the lagoons this exposed large areas of mud in the west lagoon and provided a roost for many of the waders and gulls feeding between Musselburgh and Seafield. Recently the mean level in the unfilled lagoons has risen sufficiently for this exposure to become exceptional and most of the birds now roost on the soft ash surface of the lagoon at present being filled.
Winter Roosts
The large area of mussel beds at the mouth of the Esk has probably always attracted many thousands of feeding waders, gulls and ducks. The construction of the lagoons has caused the loss of some of this feeding area, but many more birds can now roost in the area rather than make the long flight to other safe roosts such as Aberlady (Furness, 1973).
Typical numbers roosting in midwinter are:- 1600 Oystercatcher; 150 Curlew; 900 Bar-tailed Godwit; 400 Redshank; 2000 Knot; 2000 Dunlin; 80 Turnstone; 30 Ringed Plover; and the occasional Grey Plover, Black-tailed Godwit and Purple Sandpiper. Most of these roost at the lagoons, but the Redshank often go to the Loretto School playing fields, on the west side of the Esk, if not disturbed by play! Although several hundred Golden Plover can be seen on the shore at low tide, they usually roost inland as they are particularly susceptible to disturbance. Many gulls roost at the lagoons, with about 100 Great Black-backed Gulls and sometimes thousands of Herring, Common and Black-headed Gulls present. Disturbance of the roost is usually human or by the Carrion Crows which frequently torment the waders. Low-flying aircraft upset the Bar-tailed Godwit in particular and passing Kestrels, Merlins and Short-eared Owls cause pandemonium amongst the smaller waders.
Wildfowl
The west and central lagoons, still relatively free from ash, provide a haven for some of the wintering duck, especially at high tide or during stormy weather. Mallard are the main wintering dabblers, with the occasional Teal and Wigeon. They prefer the west lagoon, either feeding along the old shoreline or resting on the old sea wall that bisects the lagoon, where a few Cormorants and one or two Herons often accompany them. Goldeneye and Scaup, sometimes in their hundreds, and a few Red-breasted Mergansers feed. in the lagoons and up to 10 Little Grebes regularly winter in the central lagoon. Smews, usually 'redheads', have occurred, sometimes staying for several months and, in exceptionally cold conditions, even Coot have been driven to the lagoons.
Swans and Geese do not find the lagoons attractive, although up to 50 Mute Swans congregate near the mouth of the Esk during the spring. Whooper Swans occur occasionally in winter and there is one exceptional record of Bewick's Swans flying in from the north and landing on the sea off the lagoons.
Another bonus resulting from the construction of the outer sea wall is that bird watchers can now move much closer to the birds feeding in the shallow water just outside of the low-water line. Goldeneye and Eider predominate, although the latter are often far out, but they are occasionally outnumbered by several thousand Scaup that have strayed from their normal wintering area at Seafield. There are often a few Common and Velvet Scoters, their numbers building up during the spring, but they are all outshone by the Long-tailed Ducks, which favour the area off the central lagoon. The drakes seem to be perpetually courting and chasing the ducks and, on a calm winter's day, their calls carry far.
Winter Seabirds and Passerines
Divers are not uncommon and often come close to the lagoon wall. Several Red-throated Divers are present in winter, but both Black-throated and Great Crested Grebes build up in numbers during August and reach a peak of more than 100 in mid-September, but by mid-winter only around 30 are left. Red-necked and Slavonian Grebes are seen in ones and twos, but Black-necked Grebes are very rare, with only 2 records to date.
Cormorants are common and often seen swallowing a flatfish or struggling with an eel, but Shags seem to prefer the waters east of the lagoons and only appear in numbers in early spring. A few auks are seen in the winter, usually Razorbills, but there are some records of Guillemot and Little Auk.
The only passerines normally present in winter are Rock Pipits, Skylarks, Reed Buntings, the occasional Meadow Pipit, Linnets and Snow Buntings. The latter, which build up to 50 or more in some winters, are usually seen feeding on the weed seeds on the sides of the lagoon walls.
Summer
There is a complete change of population in the summer, with only a handful of Mallard. and the odd non-breeding Scaup or Goldeneye remaining. The wader population diminishes to about 300 Oystercatcher and a few Curlew, Redshank, Dunlin and Ringed Plover. The Ringed Plover breed on the old shore-line in the west and central lagoons and, despite the human disturbance of the area, 2 or 3 pairs succeed in raising a few young each year. The only other species that breed in the lagoons are Skylark, Shelduck and Wheatears, which bred for the first time in 1975. A few non-breeding gulls stay throughout the summer. The wintering species are joined by Kittiwakes, a small flock of which find the old sea well in the west lagoon to their liking - water level permitting.
Fulmars, Gannets and terns are regular over the sea off the lagoons, but perhaps the most surprising seabird seen in the summer from the sea wall is the Manx Shearwater. In certain weather conditions, they pass up and down the Forth by the score. The mid-summer period is relatively quiet and the bird population is at its lowest. Odd visitors do occur, such as moulting Goosanders, Garganey, Red-necked Grebes, an immature Glaucous Gull and a passing Merlin.
The Migration Periods
Of the two migration seasons, autumn provides the greatest variety of species but spring has its own special features. During April and May, many of the ducks and grebes are displaying frantically and the Knot, Dunlin, Bar-tailed Godwit and Golden Plover are changing into their distinctive summer plumages before departing. There is a big passage of Turnstones in late April, peaking at over 400, and Ringed Plover continue to pass through until mid-May. Of the less common waders, Black-tailed Godwit, Sanderling, Whimbrel and Common Sandpipers are regular spring migrants in small numbers, and both Little Stint and Temminck’s Stint have occurred. Sandwich Terns arrive by mid-April and Common and Arctic Terns in early May. A few Little Terns and the occasional Roseate Tern also appear in May. Of the passerine migrants in spring, White Wagtails and Wheatears are regular in early April and Swallows, Sand Martins and Meadow Pipits pass through later in the month.
In mid-July, migrant waders begin to reappear and numbers increase during August and September. In addition to the species that occur on spring passage a few Ruff are regular and Greenshank, Spotted Redshank and Snipe are seen occasionally. A good. spell of easterly winds brings a small influx of Little Stints and Curlew Sandpipers. The Curlew Sandpipers are normally birds of the year and the peak passage usually occurs in September. In 1972 a small party of adults appeared in late July, moulting out of their summer plumage. They were accompanied by a moulting Grey Phalarope, a species that has also been recorded in November. Although most of the less-common passage waders are of Scandinavian origin, there are two records, both in September, of North American waders - a White-rumped Sandpiper and 2 (possibly 3) Buff-breasted Sandpipers.
Although the Little Terns normally depart by the end of August, comic and Sandwich Terns can be seen well into October, although they peak in September, with many young birds being fed by their parents. The terns are quite naturally accompanied and chased by a few Arctic Skuas. Great and Pomarine Skuas also occur, but rarely come close to the shoreline.
A most interesting species seen at the lagoon on passage is the Little Gull. Although regular throughout the year in Fife and Angus, they are infrequent visitors to the Lothians. Musselburgh shares in the paucity of records in spring and during much of the autumn, but there are several records of more than 10 birds always in October and early November. There is probably a movement up the Forth at this time of the year with the Little Gulls using the relatively calm waters of the lagoons as a convenient resting place.
Greylag, Pinkfeet and, occasionally, Barnacle Geese are seen flying over in late September and October. Canada Geese, which occur in midsummer as well as autumn, are probably the English breeding birds making their moult migration to the Beauly Firth. Brent Geese are very scarce, as elsewhere in the Forth, but have occurred in October and midwinter.
Many passerines, such as Fieldfares, Redwings, Skylarks, Swallows, martins, Siskins and other finches, pass over the lagoons in the autumn without stopping. Up to 100 Meadow Pipits and 50 alba wagtails have been recorded and both Grey and Yellow Wagtails are occasionally noted. Wheatears are common on passage, but Stonechats and Whinchats are scarce. Rarities include Tawny Pipit and Short-toed Lark, and Lapland Bunting has occurred once and Shore Larks three times.
Conclusion
Musselburgh lagoons, the mouth of the River Esk and the surrounding sea is clearly an area attractive to a good variety of birds, especially wintering duck, grebes, waders and gulls. As a consequence it attracts many bird watchers. It is, in fact, an excellent place for watching birds since there are few breeding species and most of the wintering birds are easily seen without undue disturbance. A visit halfway between high and low tides is probably best for seeing the waders, since they are then feeding on the shore at the mouth of the Esk or flying to or from their roost sites. As there is little cover, windy days are usually unrewarding as well as uncomfortable. A calm frosty day in midwinter is ideal for seeing the ducks and grebes and a light east wind in spring or autumn often produces some of the less-common passage birds. Whatever the season and weather there is normally a sufficient variety of birds present at the lagoons to keep both beginners and experienced bird watchers contented.