The Salt Marshes along the River Nanny are an EU designated Special Protection Area (SPA) under the Conservation of Birds directive. These habitats are important breeding and feeding sites for many resident and migratory bird species.
Shelducks are one of the most commonly seen birds on the River Nanny. These are native birds which can be found all year round. In the summertime they will breed along the riverbank but at these times they will quickly take flight to draw potential predators away from their young. Shelduck feed mainly on aquatic snails and other small animals found in the Salt Marshes such as ragworms and clams.
The scientific name for Shelduck, Tadorna originates from the old Celtic name for the bird – Tadorne; simply meaning pied waterbird, attributing to the Shelduck’s feather patterns.
Mallard Ducks are also common and perhaps more familiar as they are found in all large waterbodies including ponds in urban parks where they may become very tame. The Mallard is much smaller than the Shelduck and has a far broader diet. These ducks will feed on many different types of plants, animals and algaes in the water. Males and females are easy to tell apart. The male has a glossy green head with grey wings. The female’s feather pattern (plummage) is speckled brown.
Grey Herons are wading birds common to all major waterways in Ireland. With a height of one metre and a wingspan of nearly two, they are one of our largest birds and an impressive sight in flight. More often however, they will be seen standing still in the water as they are ambush predators and will wait patiently until the time is right to strike the small fish on which they feed.
A relation of the Grey Heron which can also be seen on the Nanny is the Little Egret. These birds were once common to the British Isles but disappeared in Medieval times, probably because of overhunting and an extended cold period of climate change known as the ‘Little Ice age’. In recent years they have begun to recolonise Ireland and Britain, the first breeding pair in Ireland recorded in 1997 in Cork. The birds now found here are migrants or the offspring of migrants from warmer climates in Southern Europe and Africa.
The most common seabirds to be found on the River Nanny are the Black-headed Gulls. These are noisy, opportunistic seagulls which will feed on small fish and shellfish as well as scavenging on scraps from human rubbish. Although they are gulls, they will not travel far out to sea but stay close to the coast or to urban areas where food is easily found. Breeding takes place inland, usually in marshland such as that found by the Nanny. Despite their small size and adventurous feeding habits, Black-headed Gulls can live for thirty years. The black head for which they are named is only present in the summertime. In the winter, only two faint dark spots remain on the head.
Calidris Winter Visitors
Two small wading birds that may be seen on the Salt Marshes of the River Nanny from September to April are the Knot and the Sanderling. These are both members of the genus Calidris which come down from their breeding grounds in the Arctic to escape the harsh winters. The Knot is a small grey-brown bird with red plummage in Spring and Autumn. In Winter, these birds may be seen flying in very tight flocks or digging in the mud along the Nanny for the invertebrates on which it feeds. Sanderlings are less common and slightly smaller than the Knot. They can be distinguished by their paler, almost white plummage. Like the Knot, they may be seen in tight flocks, often running instead of flying to preserve energy. The Sanderling regularly feeds in breaking waves and so is more commonly found on beaches or in tidal estuaries.
Curlews are common waders on Irish wetlands and can be seen along the Nanny and much of the Irish coast. They are however, becoming less numerous due to hunting. Curlews can be identified by their long, curled bill which they use to feed on worms buried in the sand and mud. Despite this, they can be difficult to see due to their plummage which keeps them well camouflaged on the sandy banks and mudflats.
Turnstones are also common on the Nanny but like the Curlew they may be difficult to spot due to the colour of their feather patterns which blend into the surrounding mudflats. These are smaller than the Curlew with shorter, straighter bills and can be recognized by their bright orange legs. Turnstones are opportunists and will scavenge on a wide range of food sources that wash up into the estuary. As the name Turnstone implies, they will also turn stones and forage in seaweed for hiding invertebrates.
Another small wader is the Ringed Plover. Ringed plovers are even smaller than Turnstones and they cannot feed deep in the sand by touch as their bills are not long enough. They feed by sight, mainly on aquatic insects, molluscs and crustaceans. They have also been known to feed on worms buried in the sand beneath the water by kicking them up with rapid foot vibrations. Plovers are very clever and will feign injured wings to lure potential predators away from their nests which are on the mudflats.In colder countries, Ringed Plover will migrate South for Winter but in Ireland the seasons are mild enough to allow most individuals to remain year-round.
The Oystercatcher is a very recognizable wader with its black and white plummage, blazen red eye and bright orange legs and bill. As the name suggests, Oystercatchers feed on Oysters. They are on of the few waders with bills strong enough to prise open the shells of Bivalves such as Oysters, Mussels and Clams. Oystercatchers do not feed on oysters in Ireland. In addition to this, Oystercatchers may use their bills to dig in the ground for worms.
Comorants and Herring Gulls regularly come in to the Nanny from the nearby shore, especially in bad weather or during high tide. Comorants are large, black fishing birds common throughout Ireland, Europe and Asia. In the Far East, these birds are trained by fishermen to catch fish.
Herring Gulls are large, scavenging seagulls. Much larger and noisier than the Black-headed gulls, they have similarly become accustomed to human habitation and are common to landfills as well as coastlines. As well as scavenging, the Herring gull will steal eggs from other nesting birds. Like many seagulls, they have a broad diet and will feed on anything edible they can find.
Invertebrates on the mudflats
Polychaeta Worms, such as Lugworms and Ragworms make up a substantial part of the diet of many wading birds. These are marine worms which waders such as Curlews and Godwits can be often seen digging for in the mudflats.
Lugworms bury themselves in the sand at a young age and tend to stay in the same U-shaped tunnel for the duration of their lives, leaving only to breed. For this reason, Lugworms are rarely seen but their castings, similiar to that of terrestrial Earthworms, are a familiar sight on beaches and estuary shores. These castings are formed from digested soil or sand which the Lugworm swallows at the bottom of its burrow. It is likely that the Curlew’s long, curved bill is an adaptation to the U-shape of the Lugworm burrow.
Ragworms also burrow in the sand but they are much more active than the Lugworm and regularly leave their holes to forage in seaweed or even hunt other small invertebrates. Unlike Lugworms which feed only on the mud, Ragworms have very strong jaws and are omnivorous. Being more active than Lugworms however, they are also easier to find and so are hunted in turn by many waders including Herons, Egrets and Shelduck. Nevertheless, Ragworms are abundant along Irish coasts and estuaries. So much so that they are the main prey for at least 15 species of birds as well as commonly being used by humans as fishbait.
Sandhoppers (species: Talitrus saltator) are tiny crustaceans which are abundant to shores all around Europe. They are relatives of Shrimp and feed mainly on dead seaweed which they can usually be found hopping from if disturbed. Although very small, Sandhoppers are an important part of the diet of many shore birds including Turnstones and Ringed Plover.
On the Upper Salt Marshes, Sedges, Thrift and Scurveygrass grow and provide a habitat for many foraging insects and spiders.