Problems with plan for protection of slugs

ANOTHER LIFE:IN 1842, A FEW years before the Famine and while Co Kerry still had a few native sea eagles to poison, a naturalist named William Andrews found a large and unfamiliar spotted slug among mossy rocks beside Lough Caragh.

When touched, it rolled up into a ball, like a hedgehog, a habit still unique among Ireland’s 32 kinds of slug. It can also stretch itself into a thin sliver of tissue, extending a nominal 8cm or so to twice that length or more (a Houdini-like ability to squeeze through tight spaces has been attested to by disappointed field scientists opening their containers at home).

Andrews managed, however, to get his specimen to another young naturalist, George Allman, graduating in medicine at Trinity College. After some dissection, Allman introduced the slug to science as a new species, Geomalacus maculosus, or "spotted earth mollusc".

It was not until later in the century that other populations of its kind were discovered in the woods of Galicia in northern Spain, and round the corner in Portugal. Indeed, the most likely explanation for its widespread presence in south-west Ireland today is arrival in mossy packaging in early, perhaps even Neolithic, boats from Iberia.

Today, its range in Kerry and parts of Cork is mostly on moors and in woods between the mountains, from Killarney west to the Dingle peninsula. The humid air and high rainfall of the region lets it roam among the rocks of open bog and lake shores (where it is generally greeny-black with creamy white spots), as well as in the oakwoods (where it is more typically ginger, with yellowy spots). It shares with its Spanish and Portuguese ancestors an affinity with old, weathered rocks, such as Kerry’s acid red sandstone, with rich rugs of lichens, mosses and liverworts for both food and shelter.

The slug’s rarity earned it special protection under the Wildlife Act of 1976, and it became a “selection feature” in seven of Ireland’s Special Areas of Conservation in the EU Natura network. One of these covers 77,000 hectares of Killarney National Park, Macgillicuddy’s Reeks and the Caragh River catchment.

The National Parks and Wildlife Service (NPWS) felt confident that the slug was secure and might even expand its range as climate warms. But it had little actual data on how it was faring, especially outside the SAC boundaries. As new development began to threaten its Iberian populations, the animal was moved up in priority under the EU’s Habitats Directive. In 2007, in one of many Commission actions against laggardly states, the European Court of Justice ordered Ireland to establish a system of strict protection for the Kerry slug, including monitoring of its population.

No one, of course, knows how many of the creatures there are, except from counts at a handful of sites. Recently, Dr Roy Anderson did environmental fieldwork for the National Roads Authority at Ballyvourney, West Cork, and found up to 10 adult slugs in the bottom two metres in bark crevices of mature ash or oak trees, and up to two adults per square metre of exposed lichen or moss-clad rock.

But how do you keep track of an animal that hides itself under damp moss on horizontal branches of oaks, or deep in crevices on tree trunks, and that comes out mostly at night, or on wet, midge-ridden days, over a vast area of blanket bog and woodland?

Some desperation marks a new NPWS Threat Response Plan that considers ways and means. Mark with fluorescent dye and recapture at sample sites? Expensive and “not suited to large geographical areas”. Scatter tiles as traps, or contrive baited pitfalls? You can’t put those up trees (nor, indeed, half-grapefruit skins).

Hand search is the obvious option – “labour intensive, but not excessively so” – if there are certain problems about the underside of large boulders and the higher reaches of trees. While alternatives are assessed, the merits of just looking carefully inspire the Kerry Slug Survey of Ireland (go to biology.ie or kerryslug.com). Here the NPWS, with Dr Rory McDonnell of the Applied Ecology Unit of NUI Galway, are appealing for volunteer sightings, with photos of the slug’s two colourways to help.

The actual dangers to the animal, together with possible remedies and controls, have been discussed in the 59 pages of the Threat Response Plan, thrown open to consultation. The spread of rhododendron is a big one, commercial conifer forestry another.

New roads can isolate and split up slug habitats, along with new building development. Land “reclamation” could mean clearing the slug’s upland rocks, and grazing by “escaped” sheep, resident goats and wild deer all threaten the mossy interior of the woods.

One wonders how the plan will go down in a county whose mayor, worked up about road-building delays on a radio show, assigned all slugs and snails to hell.

EYE ON NATURE

While walking through a wood recently, my brother came across 18 bumble bees dead within a small area. Most of them were dismembered.

Ber Bartley, Carrick-on-Suir, Co Tipperary

Bumble bee deaths are mostly caused by either external or internal parasites which feed on the bee. The external mites are found on the body of the bee or in the air sacs. Conopid flies and parasitic wasps lay their eggs in the body of the bee and the larvae consume it from the inside.

Although our garden is blooming, there are no native bees but plenty of bumble bees and a few wasps. Will these pollinate our fruit trees?

Carmel Hourigan, Killarney, Co Kerry

Yes, and other insects.

In a sheltered, sandy bay of Lough Conn, in a couple of inches of water, I found about 10 green, slimy, round egg-like objects like balls of green algae in a gel. What were they?

John Geary, Ranelagh, Dublin, 6

They were a green alga called Nostoc, sometimes known as “mare’s eggs”.

Recently in Dún Laoghaire I saw a brown beech-like leaf swirling around as the traffic passed by. It settled on the ground and I found that it was a first generation early thorn moth.

Niamh Leonard, Dundrum, Dublin, 14

Michael Viney welcomes observations at Thallabawn, Carrowniskey PO, Westport, Co Mayo, or viney@anu.ie. Please include a postal address