Celebrating the emperor's new home

'Yesterday I went down to my bog at about midday. Blazing sun, temperature 21 degrees and the wind was blowing a bit. The water surface, though, was sheltered quite well by the clumps of rushes. There were four-spot chasers (Libellula quadrimaculata) everywhere, many more than have I seen before, between 20 and 30 of them. Then I noticed this jumbo flying high above the 737s. I got the binoculars on it, but with the bright light, it was little more than a silhouette. It was flying in a broad circle approximately five metres high over the bog.

After some minutes it flew off. I came back in my waders so I could get to the heart of the action. I spotted the hawker again, this time much lower, about two metres above water. Green thorax and blue abdomen. It alighted briefly on a willow, long enough to confirm it to be an emperor (Anax imperator)."

Angus Tyner, Co Wicklow farmer and naturalist, was noting the arrival, at his patch of wetland near Ashford, of Europe's most beautiful dragonfly, not known to be present in Ireland until last summer.

At a marsh at Lady's Island, Co Wexford, early this month, the emperor shared a lake with its lovely relative, the lesser emperor (Anex parthenope), a migrant species equally new to Ireland. Bird artist Killian Mullarney compared the two species with an ornithological exactitude: "The lessers looked distinctly darker, duller, more brownish or even blackish, depending on the light and range. The pale blue patch at the base of the abdomen is really conspicuous, and with binoculars is visible at up to 80-100m range.

"Another useful feature is that because of the comparative darkness of the thorax, which is so obviously bright apple-green in the emperors, the light-coloured (greenish-buff?) rear edge of the eyes often stood out as a narrow vertical "slash" just in front of the thorax (in profile) and head on it was often possible to detect a hint of the greenish eye colour . . ."

For observers of many kinds, amateur and professional, a whole new field of observation and excitement has been opened up by Dragonfly Ireland, the first project to record all the dragonfly species of the island and map their distribution. As a dynamic species among wetland insects, dragonflies offer an important key to the state of the island's bogs, lakes and ponds.

Dragonfly Ireland is based at Belfast's Ulster Museum (www.dragonflyireland.fsnet.co.uk) but is backed by the conservation agencies, north and south. In its second summer, the records from the south-east have continued to amaze.

Many of the sightings have come from birdwatchers at the coastal lakes, switching their attention in the dog-days of summer to the glittering wings of the Odonata. Some of them now carry the colourful pocket-pack of the first Guide to the Dragonflies of Ireland, co-funded by the Heritage Council (£2.95 sterling from the Ulster Museum shop).

For Brian Nelson and Robert Thompson, co-ordinators of Dragonfly Ireland, the challenge of the three new species for Ireland (number three is the migrant hawker, Aeshna mixta) is to sort visiting migrants from real colonists at a time of climate change.

Global warming has already brought northward movements among the southern European species. Since 1995, six new dragonflies have been recorded in Britain and the migrant hawker is one that firmly established itself, so that its spread to Ireland was just a matter of time. The emperor, too, seems to have colonised our sunny south-east. After last summer's Wexford observations of male emperors holding territories and a female laying eggs on vegetation at the edge of a pond, the sheer abundance of the dragonfly as early as June (Killian Mullarney saw no fewer than 18 in the Screen Hills area of Co Wexford) supports the picture of a recently established population.

The emperor lives for 90 days, having managed its emergence from a pond-living larva by night, to escape the birds. So it is still airborne now in sunny weather, along with a good many of the darters and hawkers among Ireland's 26 long-established resident species (the darters fly up from a perch to seize their insect prey, the hawkers hunt back and forth along an aerial "beat").

Dragonfly Ireland is just as interested in what is happening to the island's scarcer resident species, like the Irish damselfly, Coenagrion lunulatum and the emerald species of Co Kerry that fly so briefly in summer. All are northern species that could move up and out of the island as global warming takes hold.

Meanwhile, a remarkable discovery in the bird world has added to the list of Irish species. The great skua, one of the biggest and fiercest of all European seabirds, has nested and raised young this summer on an island off the west. Catharacta skua, built like a burly herring gull but with a shorter tail, will vigorously harry birds as large as gannets for the food they are carrying, and is usually seen in Ireland only among the spring and autumn processions of seabirds migrating past the west coast. Its main colonies in the North Atlantic are in Iceland and the Shetlands and Orkneys (where it is known as the "bonxie"), with an increasing number of breeding sites spread through Scotland's western isles.

Numbers have been increasing (about 8,000 pairs in Scotland), but food supply has been getting more difficult, as trawlers discard fewer fish from their catches and sandeel populations decline. Thus, while the great skua is naturally a breeding bird of sub-polar regions, north and south (and thus, one might think, likely to be pushed north by global warming), the availability of food supply may be drawing it further afield to nest.

It chooses open moorland, making scrapes among heather or rushes on which to lay just two darkly-speckled eggs. The great skua's defence of the breeding territory will include human visitors in an alarming and aggressive dive-bombing. It was this that betrayed the birds' presence on the island - left unnamed, so that egg-collectors do not target it in seasons to come. To some of them, the fury of the skuas would only add spice to an essentially selfish mission.