Rogerstown Estuary

• Category: Marine and Oceanic Biomes.
• Geographic Location: Europe.
• Summary: Ireland’s Rogerstown Estuary biome is a small marine habitat that has become a very important location for migratory birds.

Located on the east coast of Ireland some 16 miles (25 kilometers) north of Dublin, just south of the village of Rush, the Rogerstown Estuary covers a total area of 1.4 square miles (3.6 square kilometers) and is one of the major sites on the east coast of Ireland for wintering wildfowl and waders, and for birds traveling to and from the Arctic.

The estuary river meanders to the Irish Sea, with most of it having silted up over the years. This swampy and marshy area has resisted construction, and also has defied attempts over many centuries to claim much of it for agricultural use. This happens even though the mouth of the estuary is narrow, separating the Donabate Beach to the south and the Rush Beach to the north. A bridge once spanned the estuary, but it has long ago been dismantled.

The embankment, which in large part shelters the estuary from the bitter winds of the Irish Sea, has now been developed for housing along what is now Burrow Road, Portrane. Long before the houses arrived and the land was farmed, this bluff had one of the lowest variations between high and low tide of the various spots measured along Ireland’s east coast. This largely perpetual swamp led to migratory birds favoring Rogerstown Estuary, which includes 484 acres (196 hectares) registered as a Nature Reserve and 588 acres (238 hectares) identified as a sanctuary for wildfowl. Historically, the Rogerstown Estuary was within the Pale—the area administered by the English from Dublin.

The climate of the Rogerstown Estuary and vicinity is cool, averaging 49 degrees F (9 degrees C) year round. There is little seasonal variation, from a mean 40–41 degrees F (4–5 degrees C) in January and February to a mean 58 degrees F (14 degrees C) in July and August. Rain falls approximately 200 days a year, averaging 37 inches (940 millimeters) annually, with wide fluctuations.

Biodiversity

Rogerstown Estuary attracts many species of birds, and the pale-bellied Brent (or Brant) geese are the most common species. The geese feed on eelgrass, seaweed and sea lettuce. As many as 8,722 of that species of goose were counted during 1980–86, and its worldwide population has been on the increase, which has put pressure on estuaries like Rogerstown to support this thriving fauna.

Numerous other bird species use the estuary throughout the year. From fall to early spring, Rogerstown visitors include shelduck, wigeon, teal, shoveler, goldeneye, and red-breasted merganser, as well as little egret, buzzard, sparrowhawk, peregrine, and kestrel. Also attracted to the area are such waders as golden and grey plover, lapwing, knot, dunlin, black-tailed godwit, curlew, redshank, and greenshank. In fall, little stint, curlew sandpiper, and ruff use the estuary.

Because there is a garbage dump nearby, large numbers of gulls are found in the area. In the fields and hedgerows are yellowhammers and finches in winter, and common warblers including sedge, willow, chiffchaff, and blackcap visit in summer. The lesser yellowleg visits the estuary for a short time—usually for just six days each July.

Vegetation in the estuary is comprised of saltwater marshes, raised saltmarsh, wet meadows, and riverine shallows and creeks; with silver birch, alder, and larch tree stands nearby.

Effects of Human Activity

The town of Rush, on the northern fringes of the estuary, has been inhabited since Neolithic times, and was the site of a Roman fort. The swampy estuary allowed smugglers including the legendary Jack Connor to hide here, and the infamous pirate Luke Ryan was born here.

The first major threat to the estuary in modern times was the construction of the railway bridge across it in the 1840s for the main railway line from Dublin to Belfast. Known as the Great Northern Railway Bridge, it cut the estuary into two parts, but it had less effect on the wildlife than it might have had in other ecosystems, as both sides are still saltwater marshes, with raised saltmarshes and wet meadows around most of them.

An environment that attracts so much bird life is also a place where many people fish. The Rush Golf Club at the mouth of the estuary is one such hub of activity. More intrusively, the Rush Sailing Club operates from the sheltered Rogerstown Harbor, located along a pier in the estuary. The biggest problem that the estuary faces in the long term, however, is a waste dump along the site. Although birds have been able to find food among the refuse, the long-term effect of pollution on the estuary could be far more serious, with a major long-term effect on the bird life.

Further, global climate change, and the warmer air and water temperatures that coincide with it, could alter roosting patterns within the estuary, and expand the number of species that frequent the site—attracting still more avians to compete over a rich but still limited food web here. On the ground, grasses and trees could be stressed by coastal erosion from rising seas, hydrologic changes from altered salinity due to rising seas, and higher siltation levels from the runoff caused by harsher storms inland. Frequent coastal flooding has also become problematic.

Bibliography

Colgan, Nathaniel. Flora of the County Dublin: Flowering Plants, Higher Cryptogams, and Characeae. Dublin, Ireland: Hodges, Figgis & Co., 1904.

Doodson, A. T. and R. H. Corkan. “The Principal Constituent of the Tides in the English and Irish Channels.” Philosophical Transactions of the Royal Society of London. Series A, Containing Papers of a Mathematical or Physical Character 231 (1933).

Dudley, Steve, Tim Benton, and Peter Fraser. Rare Birds—Day by Day. London: T. & A. D. Poyser, 1996.

Hutchinson, Clive. Birds in Ireland. Dublin, Ireland: Country House, 1986.

Hutchinson, Clive. Ireland’s Wetlands and Their Birds. Dublin, Ireland: Irish Wildbird Conservancy, 1979.

"New Plans to Hold Back Tide." Fingal Independent, 2 Sept. 2022, www.independent.ie/regionals/fingalindependent/news/new-plans-to-hold-back-tide-39529138.html. Accessed 30 Nov. 2024.