Collins New Naturalist Library. David Cabot

Чтение книги онлайн.

СКАЧАТЬ spotted hyena. Some of these were to become extinct with the resurgence of ice during the Drumlin phase of the Midlandian cold stage (35,000–13,000 years ago).

      The Drumlin phase opened as cool interstadial with massive ice developing later and peaking at 25,000 years ago.² As the temperatures nose-dived, many animals took refuge in nearby caves where their bones lay dormant until discovered by the cave explorers. Ussher’s, Praeger’s and Scharff’s findings included woolly mammoth, red deer, giant Irish deer, reindeer, brown bear, wild boar, mountain hare, Arctic fox, spotted hyena, Norway lemming and Arctic or Greenland lemming.

      Interpretation of the historical sequence and associations of the species was beset by problems of shifting soil horizons due to water movements in the caves, much of which was caused by melting ice from the glaciers. Additional problems were created by badgers entering the caves much later, and disturbing the bones embedded in the soil when excavating their setts. There were also cases of collapsing ceilings bringing in intruders from the strata above the caves. Radiocarbon dating was not available to Praeger, Ussher and Scharff at the beginning of the century, hence the difficulty of disentangling the muddle of bones. It is only very recently, in last 25 years, that cave explorers have been able to place their finds accurately within a chronology.

      In 1993 a selection of some 30 samples of known bones, recovered from caves by early investigators and entrusted to the quiet security of museums, had small extracts of collagen removed for radiocarbon dating at the Oxford University Accelerator Unit. The programme was devised by Woodman & Monaghan.²⁷ The project had three aims: to discover (i) which mammals were in Ireland before the final glaciers of the Midlandian cold stage; (ii) which animals were present afterwards in the late glacial period and (iii) which were present in the postglacial period from some 10,000 years ago.

      The radiocarbon results (given as median dates in years ago and rounded to the nearest 100), based on bones from Castlepook and Foley’s caves in Co. Cork and Shandon cave, Co. Waterford, showed that in the ice-free zones in Cork and Waterford giant Irish deer (32,100), reindeer (28,000), Norway lemming (27,900), woolly mammoth (27,200), brown bear (26,300), red deer (26,100) Arctic lemming (20,300) and Arctic fox (20,000) were present. During the late glacial period the following species were found in caves in Cork, Sligo, Clare and Limerick: reindeer (12,500 and 10,900), brown bear, (11,900 and 10,700), red deer (11,800), giant Irish deer (11,800), wolf (11,200) and Arctic lemming (10,000), showing that the first four species soldiered on into the late glacial period (13,000–10,000 years ago). The gradual warming up of the landscape was rudely interrupted by the Nahanagan stadial, during which the mean annual summer temperatures may have been less than 5°C. Many questions remain as to the impact of this sudden temperature reversal on flora and fauna. However, it should be remembered that Arctic foxes, Greenland lemmings, Arctic hares, ermines, wolves and musk ox as well as hundreds of insect and flowering plant species are able to survive Greenland winters when temperature drop as low as -20°C with summer temperatures higher than experienced during the Nahanagan stadial. The question applies to all the previous cold periods. If some animals and plants were able to survive the Drumlin phase of the Midlandian and subsequent Nahanagan stadial then the need to argue for their land bridge arrival in Ireland is considerably weakened. Many of the large herbivores disappeared, together with their carnivore predators, with the decline of their important grasslands.

      Without further information from a large scale radiocarbon dating programme it will remain a moot point whether the known early mammals such as Arctic hares, red deer and wolf, and species such as stoats, otters, pine martens, etc., for which there is no evidence yet of their early occupancy, achieved a continuous presence in Ireland through to the postglacial period, when a warmer and a more environmentally friendly landscape re-emerged, or whether they re-entered Ireland as immigrants across the land bridge. All that can be said is that Woodman & Monaghan dated red deer bones from 4,200 years ago at Stonestown, Co. Westmeath and to 2,020 years ago at Sydenham, Co. Down and that brown bears were present in Ireland as recently as 8,900 years ago – as testified by remains at Derrykeel Bog, Co. Offaly. They were contemporary with the first human settlers at Mount Sandel on the lower reaches of the River Bann, just south of Coleraine, Co. Derry.

      Animal bones recovered from County Clare caves. 1–5 Crane bones; 6 Hawfinch? 7 Arctic fox; 8 Domestic cat; 9 Irish wild cat. From Scharff et. al.²⁶

Lynch & Hayden have argued that the range contraction of the Arctic hare and stoat, both present in the Castlepook interstadial (35,000 years ago²⁸), before the Drumlin phase of the Midlandian period, into an ice-free southern Co. Cork, together with their genetic isolation from their assumed British and Continental mother stock, may have been sufficient time for both the stoat and hare to develop their subspecific characteristics.²⁹ They tested morphological differences by multivariate analysis of cranial measurements between Irish, English and Scottish carnivores – badger, mink, otter and stoat. Significant differences between English, Scottish and Irish badgers, otters, mink and stoat populations were demonstrated – the greatest were between the Irish stoat and its English counterpart, thus strengthening the argument for the stoat being a glacial relict species. Little evidence was found for musteline colonisation of Ireland via a land bridge between northeast Ireland and Scotland. The evolution of established subspecific differences which separate Irish hares and otters from their English relations would also have been facilitated by their genetic isolation provided by their presence in Ireland some 35,000 years ago.

      Woodman & Monaghan also attempted to unravel the history of the horse in Ireland.²⁷ Was it introduced around 4,000 years ago or was it a survivor, in its wild form, from the late glacial to the postglacial period – as is the case in Britain? The subject is still open to debate as one horse bone, recovered from Shandon Cave, near Dungarvan, Co. Waterford, gave a radiocarbon date indicating that it was more than 40,000 years old.² This places the wild horse in Ireland long before a series of horse bones from five widely separated caves from Antrim to Clare, which gave a range of dates from 1,675–120 years ago. These latter datings would support the idea that the horse was introduced late to Ireland.

      Red deer

      Red deer were part of the rich mammalian fauna during the Midlandian stage prior to the Drumlin cold phase. Radiocarbon dating shows them present in Co. Waterford from at least 26,100 years ago with more recent records from 11,800 (Co. Sligo) and 4,200–2,000 years ago (Westmeath, Kerry, Clare and Down).²⁷ It would appear that they survived the Drumlin phase of the Midlandian cold stage, possibly along with other mammals whose bones have not yet been found, to earn ‘native’ status in the Killarney Valley, Co. Kerry. However, the degree to which the Killarney deer are unadulterated descendants of the original native stock is a complex and unresolved issue.

      Scharff wrote of ‘red deer which still survives in a semi-domesticated and not entirely pure strain in the forests of Killarney.’³⁰ Moffat stated in 1938 that ‘These Deer cannot be claimed as a perfectly pure breed, for inter-breeding has occurred with imported animals, and the extent to which this has prevailed is not easily estimated. The Red Deer at Muckross have, however, at least a fair claim to represent in the main the old native stock that is known to have been abundant throughout Ireland in early historic and pre-historic times.’³¹ Finally, Whitehead declared in 1964: ‘Of the three established herds, only the Kerry deer can claim descent from the original wild stock, but even these cannot be considered as being perfectly pure bred.’³² Whitehead has produced the only evidence questioning the status of the deer. He reported that during the nineteenth century both Lord Kenmare and Mr Herbert of Muckross, Co. Kerry, brought in fresh blood which included five stags from Co. Roscommon – presumably from the herd at Croghan House Park, Boyle, where a small herd existed until 1939. Around 1900 Lord Kenmare brought in a stag from Windsor Great Park, England, which was liberated in Derrycunihy wood. Also at this time some stags from Muckross were rounded up and sent to Scotland in exchange for Scottish stags. Since the latter arrived, occasional СКАЧАТЬ