Hitting the bull’s eye..

Zoe Devlin on the ‘new’phenomenon that is Dublin Bay’s Bull Island

It sounds strange to talk of an island as a ‘new’ island but Dublin’s North Bull Island is just that. It is a National Bird Sanctuary, a National Nature Reserve, a Special Protection Area under the EU Birds Directive and a Special Area of Conservation under the EU Habitats Directive, a UNESCO Biosphere Reserve and the subject of a Special Amenity Area Order. All those fancy titles .. and two centuries ago it wasn’t even there.

A newcomer to our shores, this unique wildlife sanctuary came about as a result of a wall, the North Bull Wall, which was constructed in 1825 to prevent silting across Dublin Bay, particularly the mouth of the River Liffey. The granite that was used in the construction is said to have been quarried in Dalkey and brought across the bay, using convict labour. The tidal effects resulted in deepening the entry to the river causing a large part of the silt to shift, gradually building up against the North Bull sandbank and eventually creating an island. Since that time, the island has progressively enlarged and is now 5km long by 1km wide, and indeed it is still growing, stretching northwards, very slowly, towards Sutton. At its southern end, the island was originally connected to the mainland by a one-lane wooden bridge and, a mile or so further north, a causeway was built in the 1960s to allow for more traffic. I first set foot on the island in the 1950’s, not realising what an absolute paradise it would become for me, how much I would learn and love about it over the next seven decades.

Black-tailed Godwit

What I like most of all about the Bull island is that it is accessible to folk living in Dublin city and county who don’t need to travel far in order to see quite an amount of biodiversity. A slow summer walk southwards from the Interpretative Centre is most rewarding, not only for the flowers but also the insects – butterflies such as the rare marsh fritillary can be seen flying in late summer, seeking out devil’s-bit scabious, the foodplant its caterpillars will need to survive. And then in wintertime, the wetland birds come into their own and all it takes is an enormous amount of patience and a bit of luck, but when a good sighting happens, it is always worth the effort and energy expended.

Abundance of nature

I have returned to the Bull Island many times, relishing in the abundance of nature it contains. Not only is it an immensely important habitat for wild plants, birds, insects and mammals but the access to it is quite user-friendly, giving those with an interest in nature plenty of energy and time to savour what is on offer. My greatest joy has been in finding the profusion of wildflower species it supports in spring, summer and autumn and, as winter approaches and the birds come into their own, I love to wrap up warmly and watch the avian migrants that have arrived from colder parts of the globe.

Male Teal

It is hard to have a favourite – godwit, dunlin, knot, lapwing – they are all outstanding creatures but I’m always thrilled when I spot a certain medium-sized duck, the unmistakeable shelduck. Although we have many of these as residents, they are joined in October by their cousins that migrate here from the Baltic and Scandinavia. They then overwinter on tidal mudflats and sheltered estuaries where their table d’hôte consists mainly of mudsnails. They are most handsome birds and their good looks make them very easy to identify. Mostly white, they have dark-green-almost-black heads, red bills – the males having prominent knobs at the base of their bills – and a drape of chestnut across their breasts. Their elegance is completed by black scapulars (shoulder-blades) and reddish-pink legs.

All year round there is plenty going on in those mudflats and one species of bird to watch out for is a smaller duck – the teal. Always a delight to see, the males and females have quite different plumage; his head is brown and bears striking green, yellow-bordered patches that extend from his eyes towards the back of his neck. Grey bodied, he has a horizontal white stripe along each side of his body, a green speculum (a patch on the wing feathers) and a creamy-yellow patch that is bordered by black on either side of his rump. The plumage of his mate is mainly brown, streaked and mottled dark, with green speculum. I often wondered why many so male birds are beautifully attired whereas the female only gets a boring outfit .. one answer is that the females mainly look after the offspring and therefore their garb draws less attention from would-be predators. The other reason is that the male needs to be a snappy dresser in order to attract a female. The usual habitat of these little ducks is in reedbeds, inland marshes and estuaries where they feed on seeds of sedges, grasses, molluscs, small crustaceans and algae.

Away from the waterfowl, there is a cornucopia of beauty to be found within the island. This is the wealth of wildflowers – an unexpected bounty best visited during the summer months. In late May, there are abundant stands of pyramidal orchids towards the southern end of the island. They carry small cones of magenta blossoms on stems rarely more than 50cm high and then, in June, many more orchids come into flower. Looking carefully, I have managed to spot frog orchids and common twayblades, both of which are chameleon-like masters of camouflage with greenish-yellow flowers that blend into the background vegetation only too well. Then there are the splendid marsh-orchids – some an amazing shade of ruby or carmine, others purple, mauve or lilac. As June turns into July, vast swathes of marsh helleborine spread widely across the landscape. At first they seem to evade the eye but once they have been spotted, they appear to flow across the ground like little rivers, often scattered across marshes, lake-shores, damp pastures and wet dune slacks. Small wasps and other insects pollinate them but they have a ‘belt and braces’ system for survival as they also multiply by new shoots on their rhizomes (underground stems).

The soil on the island is sandy and strewn along the meandering pathways and the low sandhills are little splashes of mauve and yellow; a closer look reveals very small pansies – both wild pansy and dune pansy. One tiny plant to look out for is the pink-flowered lesser centaury, only the size of a match-stick. Due to a decline in the habitat required by this little species, it is protected under the Flora (Protection) Order, 2015 and is classed as ‘near threatened’ in the Red Data List of Vascular Plants 2016. Damp knees are a small price to pay for a glimpse of such a gorgeous little rarity! Then there are glimpses of the dusty-pink ‘paws’ of hare’s-foot clover, visible through the tall stems of marram grass and in a few soggy areas are damp-loving plants like marsh pennywort, a species that must bear one of the smallest flowers I’ve ever seen. I can’t imagine the size of the insect that pollinates it! Incidentally, as well as a pair of binoculars for viewing the wildfowl, it is always worth carrying a small magnifying lens with you on these forays into nature; a x10 magnification is perfect and it is amazing what detail becomes visible.

Common Spotted-orchid

Invasive alien

But there’s an introduced plant species on the island, that has totally lost its manners and is now categorised as an invasive alien in Ireland. This is sea-buckthorn, a rough, thorny, shrub that originated in China and bears stunning masses of orange berries in crowded clusters in autumn, providing an avian takeaway for the visiting and resident birds which then go on to do a good job of distributing the seeds, although it also spreads rapidly on suckers.

Sea-buckthorn was planted many years ago to stabilise the dunes and provide shelter from the wind and it has thrived, far too well. Sadly its ability to spread rampantly has caused the demise of other plants by crowding them out and altering their habitat. It colonises vast areas with its stiff, impenetrable branches and pale, dull green leaves that look as if they were sprayed with an aerosol of silvery dust.

As well as birds and wildflowers, other elements of our rich biodiversity have been recorded from this precious habitat including common and grey seals, Irish hares, red foxes, Irish stoats, common frogs, pigmy shrews, common lizards, rabbits, bats and otters. Sadly the hares are no longer to be found here.

In order to safeguard this precious habitat – and particularly breeding and roosting grounds for birds – measures have been introduced (by Dublin City Council) that are designed to restrict access to certain high-sensitivity areas, especially during the breeding season. No longer is there access for the public to the northern salt marsh, where birds roost and seals give birth. These restrictions came into effect in early summer, 2023, so it is probably a little early to draw firm conclusions but DCC has already noted encouraging signs. As time goes by a clearer picture should emerge and with the help of five newly appointed Conservation Park Rangers, there is cause for optimism. Their role includes direct engagement with the general public, communicating the rationale behind the access changes, and the island’s unique ecology. Part of their role is to ensure that dogs are kept on leads at certain times, particularly in sensitive zones because, in the past, these animals have been seen to cause major disturbance problems.

Protected species Lesser Centaury

As as child, growing up in 1950’s Dublin, I remember how the Bull Island’s beach area, Dollymount strand, would be crowded with folk, at weekends in particular, all out for a bit of fresh air and fun. In more recent times, other activities have become popular such as kite-surfing, jogging, paddle-boarding and the now-banned sport of sand-yachting. There are also two golf clubs, St Annes in the north of the island and Royal Dublin at the southern end.

One last nugget of information about this amazing Dublin oasis – by using photosynthesis, the plants in the island’s saltmarsh are capable of absorbing quantities of carbon dioxide from the atmosphere, through their stems and roots. These gases are stored in what are known as carbon sinks, reservoirs that store carbon, effectively reducing the concentration of greenhouse gases in the atmosphere and lending a helping hand to the survival of our planet.