How did these toads come to Ireland and why are they restricted to a relatively small sandy coastal area in west Kerry? Are they relicts of a once more widely spread population from a warmer and drier period? What do we make of Chute, writing from Blennerville on 31 March 1846, to Thompson, author of The Natural History of Ireland, ‘I believe the Natter-jack is indigenous to Kerry, though there is an old tradition that a ship at one time brought a lot of them and let them go at the head of Dingle Bay. This is born out by the fact that this is the only part of Kerry that they are met in: a district extending from the sandhills at Inch at Rosbegh at the head of the bay (where they are most numerous) to Carrignaferay, about ten miles in length in low marshy ground, and about the same number in breadth.’45 A century later, Praeger spoke contemptuously of this invasion hypothesis: ‘Could misdirected ingenuity go further than to suggest the importation or shipwreck of a cargo of toads on that lonely and harbourless coast!’20
Beebee says of natterjack toads in Ireland: ‘It seems much more likely that they are truly indigenous’ and he argues that they are part of the Lusitanian biota of the Iberian peninsula which is well known in southwest Ireland.46 However, the natterjack can hardly be considered Lusitanian with a European distribution stretching northwards to southern Sweden and into western Russia.
Their indigenous status is also supported by Praeger who wrote ‘There is no doubt that in spite of its extremely restricted range the animal is indigenous in Kerry – a relict species like some of the Kerry plants.’20 The only real evidence to support the indigenous status of the toad comes from the discovery of their bones from a megalithic cemetery at Carrowmore, Co. Sligo, during the 1970s.47 But the status of these bones is not clear. Were they contemporary with Neolithic man or did they arrive much later and end up buried in the soil at the same spot? Whatever the explanation, this would be the first evidence of the natterjack existing outside its very restricted Kerry range.
In fact, there are two flies in the indigenous ointment. First, the natterjack’s restricted distribution and its failure over its presumed long period of residence to colonise other available habitats and second, the lack of place names incorporating the Irish for ‘toad’.36 Both would argue against its native status. On the other hand, it would be wrong to dismiss completely the possibility of their arrival from a ship at the head of Dingle Bay for two reasons. First, local stories in Ireland are more than often grounded in fact and there is no reason to disbelieve this one. Smith, in his survey of Kerry published in 1756, wrote about Castlemaine Harbour in the mid-eighteenth century: ‘Deep enough for vessels of 50 tons or upwards to sail up to the bridge at high water where they may lie on soft oozy ground to discharge. Some vessels are unloaded here on the bankside which serves as a wharf. These are generally freighted with rock salt from England, and others are laden with iron ore which is carried on horses to the iron foundries.’48 Some toads could have been caught up in sand ballast, brought from European ports, and dumped on the shore at any point of the operations described above. The dumping of ballast on both sides of the Dingle Peninsula would explain the toad’s presence at Castlegregory and Castlemaine sites. Secondly, toads would have almost certainly been noticed and commented upon prior to their first recording in 1805 had they been present in the area over the centuries. Also, how could such an astute recorder as Smith overlook them in the 1750s? Finally, the non-indigenous hypothesis is strengthened by the absence in Ireland of the common toad whose European distribution is even more widespread than the natterjack’s, with populations extending much further north and east. It might therefore be suggested that the factors operating against the common toad’s spread westwards were also operating against the natterjack: both were probably prevented from hopping across land bridges connecting Britain and Ireland because those had already been drowned.
The hypothesis of the natterjack’s arrival by boat is also supported by some comments by Cambrensis. When discussing the fate of poisonous reptiles when they arrive in Ireland he states ‘I have heard merchants that ply their trade on the seas say that sometimes, when they unloaded their cargoes at Irish port, they found toads brought in by chance in the bottom of the holds. They threw them out still living on to the land…’.43 One way of throwing more light onto the natterjack’s status would be to investigate biochemical and genetic divergence between the Irish, British and European populations by electrophoresis or more sophisticated genetic techniques. Some historical research into the traffic of boats and the way their ballast and cargoes were handled in Dingle and Tralee Bays might also be helpful. The occurrence of jettisoned ballast on Irish shores is well known: it has been accepted that the large erratics of flint on the foreshore at Kilmore Quay, Co. Wexford, came by boat, while the many small boulders of brown granite found near the entrance of Lough Hyne, Co. Cork, close to a rough disused landing place were the same rocks used to build the lighthouse works on Clear Island, Co. Cork – they came from Cornwall. In Broadstrand Bay, on the west side of Courtmacsherry Bay, Co. Cork, a variety of igneous pebbles and boulders, most of them granite with coloured feldspars, were found in the clefts of an early glacial rock platform as well as in the gullies of small beaches. Farrington was in no doubt, having examined all likely local sources, that the boulders and pebbles in question were ballast, probably deposited 60 years before he recorded his observations in 1965.49
Freshwater fish
The first fish to come back to Ireland after the last Ice Age were the euryhaline species (those that can tolerate a wide range of salinity and are encountered in both salt and fresh water). These fish are able to maintain the concentration of chemical salts in their blood and body fluids regardless of the changes in the water around them. Thousands of years ago they almost certainly cruised around the coastline, following the northwards retreat of the glaciers, exploring the unfolding and warming aquatic systems, and penetrating the ice-free rivers and lakes. Maitland considered that the following 12 euryhaline fish colonised the freshwater systems of Ireland in early postglacial times:50 sea lamprey, river lamprey, Allis shad, Twaite shad, Atlantic salmon, brown trout, Arctic charr, pollan, smelt, European eel, three-spined stickleback and ten-spined stickleback. The latter, however, is considered by some to have been introduced (see below).
As to the stenohaline species (those that can tolerate only a narrow range of salinity), a question mark prevails over their provenance. The issue is twofold. Firstly, they are non-migratory although some, like the pike, have a capacity to spread rapidly across the land through interconnecting lakes and rivers. Secondly, they were not suited to the salt waters that surrounded all Irish shores from postglacial or earlier times. The four possible explanations for their presence are that they were already present during the last interglacial period and survived the final phase of the Ice Age in sheltered ice-free ponds; that they swam into Ireland, using the waterways in the land bridges between Ireland, Britain and the Continent; that they were once able to tolerate salt water and swam into Ireland across the sea, or that they were introduced by man or by some other agent.
The following species are generally considered to have been introduced to Ireland by man:51 brook lamprey, pike, carp, gudgeon, tench, bream, minnow, rudd, roach, dace, stone loach, perch and ten-spined stickleback. When were these first brought into Ireland? The weight of expert opinion is that probably most, if not all, were introduced sometime between the Norman invasions and the late nineteenth century. An examination of the Irish names for fish provides some corroborative insights: salmon or brown trout, not in the above list, have at least 30 different Irish names – including many local variants – authenticating their ancient presence in Ireland. By contrast, the dace and tench, both relatively recent arrivals, have only one and two Irish names respectively.52 However, this is subject to caution, as the Arctic charr and pollan, both prehistoric but rather scarce species, and not known to many, only carry a few names.
Cambrensis provides clues as to the origin of certain fish. The following translation, quoted by Went, is by Forester from Wright’s The Historical Works of Giraldus Cambrensis.53,54
‘Sea-fishes are found in considerable abundance on all the coasts. The rivers and lakes, also, are plentifully stored with the sorts of fish peculiar to those waters, and especially three species: salmon