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FERAL SHEEP IN NEW ZEALAND
A. H. WHITAKER
Ecology Division, Department of Scientific and Industrial Research
1 Introduction of Sheep
Sheep have been an essential part of New Zealand agriculture from the very earliest times of pakeha settlement. The first introduction must be credited to Cook in 1773, but the pair he landed in Queen Charlotte Sound are known to have died (Beagleho1e 1961). Forty years later, in 1814, Samuel Marsden brought sheep from Sydney to the Bay of Islands (Miller 1950). In 1834 John Bell settled on Mana Island with 102 merinos from New South Wales and four years later was able to export four bales of wool to Sydney (McNab 1913). By the 1840s when the period of colonisation had really begun, introductions of sheep from Australia had become commonplace. Indeed the New Zealand Gazette and Wellington Spectator reports five ships landing sheep within a fortnight in 1841 (File Note dated 11.3.1964, Turnbull Library). The sheep introduced during this period were almost entirely from Australia and were predominantly merino.
With the establishment of a pastoral industry the sheep numbers rose rapidly by breeding and massive introductions from Australia. In 1855 there were .75 million, in 1861 2.8 million, in 1864 4.9 million and in 1867 8.4 million. By 1880 there were over 13 million sheep in New Zealand which were still predominantly merino, but by 1890, merinos had dropped to 34% of the estimated 17.5 million sheep in the country (Stevens 1966).
2 Establishment of Feral Sheep
Throughout this early period of development, sheep-farming in New Zealand was largely on a free-range, set-stocking basis. Fences were very poor or non-existent and the animals were generally allowed to wander freely over open country. They were mustered only for shearing or tailing. As many properties were very large or very rough it was inevitable that some sheep should be left behind to form wild or feral flocks. By the l880s "wild" sheep had become common in the mountainous districts of the South Island (Thomson 1922), in Hawkes Bay (Guthrie-Smith 1953), and doubtless elsewhere in the country. Feral sheep were reported from the Chathams in 1900, Kapiti in 1919, and in 1922 were said to be "still abundant in the wilder parts of the country... especially... Marlborough" (Thomson 1922).
3 Control of Feral Sheep
By the early 1900s sheep farming had become more intensive and organised. The feral sheep flocks were gradually reduced to the more inaccessible areas, though they received a boost in the Depression when many isolated farms were abandoned. Since that time however their numbers have dwindled as a result of improved farm management and official control. Since the inception of the wildlife control policies, wild sheep have been killed as a sideline to deer and goat control, though initially there was a certain amount of reluctance to shooting sheep because of the provisions of the Stock Act. After the war, when control operations against ungulates really got moving, a determined effort was made to remove sheep, especially from problem areas such as Marlborough, and in 1946 over 5000 sheep were killed (Wodzicki 1950). In the decade 1951-1961 an average of over 2000 per annum were accounted for but tallies did not drop during that period (Howard 1965). However control operations must have been effective as since then a number of feral flocks have been completely eliminated and official tallies from all districts have dropped steadily over the last four years (197l-l975) from 169 to 68 (NZFS Files).
4 Present Flocks
Nowadays flocks of feral sheep with clearly self-maintaining populations exist at about a dozen places on the mainland from Hawkes Bay to Southland, and on the out-lying islands of Campbell and Chatham. No doubt there are some other localised flocks which have not been reported and in many districts there are mismustered sheep which run wild for a few years before being brought back into the fold. All the truly feral sheep seem to be of merino origin or contain a high proportion of merino blood.
A. Hawkes Bay
At present there are two distinct flocks of feral sheep - one in the north-eastern Ruahines and the other on the Mohaka River. The first of these, referred to as the Omahaki flock, occurs around the confluence of the Ngaruroro and Taruarau Rivers in the Eastern Ruahine State Forest and on Big Hill and Omahaki stations. It is spread over an area of approximately 7000 ha of scrubland, screes and bluffs. Population estimates vary widely but there appear to be several hundred animals. The origin of this flock is uncertain though they are known to have been living in a feral state for over 50 years. They would constitute the last part of the much larger feral flock that probably had its beginning in the merino sheep that were grazed on the open tops of the Ruahines last century. As recently as fifteen years ago feral sheep were known from six different Ruahine catchments (Cunningham 1962) but they have now been reduced to this one area in the northeast. Official shooting, aimed at reducing the browsing pressure on unstable country, reveals tallies which have dropped in the last decade from 300/annum to about 40/annum at present (A. N. Gilmore, in litt. 6.VI. 1975).
The Mohaka flock comprises several groups which may or may not be discrete. All are on or near the banks of the Mohaka river between the Te Hoe and Waipunga Rivers, behind Tutira. All in all there appear to be less than 1000 sheep spread over an area greater than 30 000 ha. Numbers in this area are apparently diminishing but the reason is not official control so much as habitat destruction - the land is being developed for farming. In one area where only six years ago it was possible to see mobs of 10-12, feral sheep are now 'rare' (A. N. Gilmore, in litt. 6.VI.1975). The origins of the Mohaka flocks are also unknown but their age is probably similar to that of the Omahaki flock. It is interesting to note they exist in roughly the same area from which Guthrie-Smith (1953) described feral merinos in the l880s. Certainly in this area the change from merinos to longwools was virtually complete by 1900 so this presumably provides an indication of age.
Marlborough, as stated earlier, has long been a stronghold of feral sheep. Today, there appear to be only two flocks of any significance left - one in the Wairau and the other in the Clarence. The Wairau group is the smallest and of doubtful antiquity. There are only a few hundred animals scattered through the headwaters of the Branch, Leatham and Waihopai and they probably receive frequent injections of new blood from the merino and cross-bred sheep run in the vicinity.
The flock in the Clarence is larger, 2-300 in the vicinity of the Boundary and Ouse Rivers and a similar number in the Mead River. Local opinion is that they have their origins in the 1880s and that they contain a larger proportion of pure merino than the Wairau group. Intensive animal control is still carried out in both areas as means of relieving browsing pressures on very unstable slopes and tallies over the last few years have been about 100/annum (C. J. Wishart, in litt., l8.VIII.1975).
Also in Marlborough there is a feral flock on Arapawa Island in the outer Sounds. This flock, numbering about 120, occupies an area of 700 ha of forest and scrub on the seaward slopes of the island. Apart from sporadic recreational shooting there has been no control. The numbers and range have apparently remained constant over the last 60 years and the available evidence suggests the flock had its origins about 100 years ago. They are almost certainly derived from Australian merinos taken to the island from the Wairau Valley late last century. There is no suggestion of cross-breeding with domestic stock and apparently no other conflict of interest.
South of Oamaru there is a flock of feral sheep in the Waianakarua catchment at the eastern end of the Kakanui Range. Little appears to be known of these animals but it seems that there are about 1000, that are of merino origin, and that the flock is about 50-60 years old. The local farmers consider them cause for concern so the implication is that there is interference with domestic stock, with possible cross-breeding, and perhaps competition for grass.
The Hokonui Hills in Southland are the haunts of another feral flock but again records are patchy. Estimates of numbers vary from 'a few hundred' to 'over a thousand'; the distribution seems to be bush edges and clearings especially to the east and south of the range. They are believed to stem from an introduction of 400 Saxon merinos from Tasmania in 1858 but this has not been substantiated. This flock is at present being destroyed, supposedly as a disease (bovine Tb) control measure. A number of people, mostly local farmers, and a variety of organisations, such as Massey University and the New Zealand Wool Board, are most disturbed that such a control operation could be started without some assessment of the animals worth.
F. Chatham Islands
There are two feral flocks known from the Chatham Islands. Near the southwest corner of the main island is a very small flock of merino sheep which presumably pre-date the change to longwool breeds. On Pitt Island there is a comparatively large flock of about 2-3000 sheep spread over 2500 ha of the southern half of the island. Saxon merinos are known to have been taken to South East Island in 1841 by Baron von Alsdorf of the Hutt Valley (Engst manuscripts, Canterbury Museum Library), and their progeny were moved on to Pitt Island a few years later. It is possible the present sheep stem from this early liberation but at least it is certain they have been living wild for over 70 years. There is no evidence that either of the Chatham flocks have expanded or contracted in the last 10-15 years but there are no data for earlier periods. As part of the development of a chain of Flora and Fauna reserves some of the Pitt Island flock are to be killed this year. However, as many hundreds of sheep will remain, this control is in no way a threat to the population as a whole, provided that some protection is given to those that remain.
G. Campbell Island
Subantarctic Campbell Island is the home of New Zealand's best known flock of feral sheep (Wilson & Orwin 1964, Taylor, Bell and Wilson 1970, Bell & Taylor 1970). In 1894 a grazing lease was taken up and in the following year sheep were landed on the island. The main introductions were in 1901 when 2000 merino 2-tooths were taken ashore, and in 1902 when 1000 of unknown breed were landed. The present sheep are recognised as being quarter to half-bred merino longwool cross with the longwool component variously described as Lincoln, Leicester or Romney. The island was farmed until 1931 when the remaining flock was abandoned to run wild. The maximum population of about 8500 occurred in 1916 but by 1931 numbers had halved. The population continued to decline until the early 1960s when only 1000 sheep were reported, but a dramatic and unexpected increase brought the numbers back to 3000 by 1969. In 1970 a fence was erected across the island and, as part of a long-term study on the effects of sheep on subantarctic vegetation and seabirds, all the sheep in the northern half were shot out.
5 Differences between New Zealand Populations
The Campbell Island flock is the only one that is known for certain to contain anything other than merino blood. Nevertheless the other feral flocks have interesting differences between them that may be attributable either to the particular strain introduced originally, or the degree and length of isolation, or even the peculiar selective pressures imposed by their environment. Two of the flocks (Arapawa and Pitt) have a remarkably high proportion of pigmented animals (over 90%) and there are indications that in the Omahaki flock the proportion of blacks is increasing. A high proportion of black was reported by Guthrie-Smith (1953) for feral sheep at Tutira in the 1890s, and for Kapiti Island feral sheep in the 1920s (J. T. McCaw, in litt., 21.IV.1975). Between the sheep of Arapawa and Pitt there are differences in the fibre diameter distributions. The follicle density and SP ratios in Arapawa sheep are less than half what would be expected in merinos and there are indications that a similar lowering has occurred in other flocks, including that on Campbell Island. Many feral sheep seem to be able to effectively lose their fleeces yet the mechanisms involved are not yet understood.
So far only three of the feral flocks have received any scientific attention - those at Campbell Island, Arapawa Island and Omahaki. DSIR, MAF and University staff have all been involved in the Campbell Island research which has covered such diverse topics as ecology, population dynamics, health and parasitism, fleece and wool, physiological adaptations, etc. Arapawa Island sheep have also been studied with respect to ecology, population, behaviour, health, fleece and wool, and blood chemistry. Omahaki has just had preliminary field observations, and wool, skin and blood sampling. I believe MAF is shortly looking at Hokonui sheep.
B. Past Opportunities
Apparently nothing is known of the flocks which are now extinct. Of the recently eliminated ones, the Takitimu Mountains flock in Southland may have been of considerable interest because of its location in an area where merinos are no longer run (a few may in fact survive). Those in the Glens of Tekoa or Oxford State Forests in Canterbury were probably of little significance. The sheep of Kapiti Island in the late 1920s seem to have been of interesting stature and colour; no one would deny that it was essential to remove them from the sanctuary but it would have been wise to examine them before removal. A more recent example was the sheep on the small and remote islands of South East and Mangere in the Chathams group which were removed in 1961 and 1968 respectively (Atkinson and Bell 1973). To make the assumption that their remoteness would indicate a rare or interesting strain would be wrong as they were modern Romney-cross stock and had been farmed to within 2-3 years of their removal. However they were so isolated that their health and parasite status could have been extremely interesting. This would not be an excuse to prevent their removal, which was to my mind a necessity, but an opportunity during the control kill which should not have been lost.
Atkinson, I. A. E., Bell, B. D. 1973: Offshore and outlying islands. In Williams, G. R. Ed., The Natural History of New Zealand. A. H. & A. W. Reed, Wellington.
Beaglehole, J. C. 1961: The Journals of Capt James Cook: Vol 2 The Voyage of the Resolution and Adventure, 1772-1775. Hakluyt Society: Cambridge University Press, Cambridge.
Bell, B. D., Taylor, R. H. 1970: The wild sheep of Campbell Island. Forest and Bird 178 : 6-10.
Cunningham, A. 1962: Catchment condition in the Ruahine Range. New Zealand Forest Service, Protection Forestry Report No 23. Unpublished.
Guthrie-Smith, H. 1953: Tutira – the story of a New Zealand sheep station. Blackwood and Son, London.
Howard, W. E. 1965: Control of Introduced Mammals in New Zealand. Dept Scientific and Industrial Research, Information Series No 45.
McNab, R. 1913: The Old Whaling Days. Whitcombe & Tombs, Wellington.
Miller, I. S. 1950: The History and Evolution of Sheep Breeds 3: Developments in New Zealand. New Zealand Journal of Agriculture 80 : 133-144.
Stevens, P. G. 1966: Sheep farming. In McClintock, A. H. Ed. An Encyclopedia of New Zealand. New Zealand Government Printer, Wellington.
Taylor, R. H., Bell, B. D., Wilson, P. R. 1970: Royal Albatrosses, fera1 sheep and cattle on Campbell Island. New Zealand Journal of Science 13 (1) : 78-88.
Thomson, G. M. 1922: The Naturalisation of Animals and Plants in New Zealand. Cambridge University Press, Cambridge. 607p.
Wilson, P. R., Orwin, D. F. G. 1964: The sheep population of Campbell Island. New Zealand Journal of Science 7 (3) : 460-490.
Wodzicki, K. A. 1950: Introduced Mammals of New Zealand – An ecological and economic survey. New Zealand Department of Scientific and Industrial Research, Bulletin No 98. 255p.[This paper is a reformatted extract from The Value of Feral Farm Mammals in New Zealand, edited by A. H. Whitaker and M. R. Rudge, Department of Lands and Survey, 1976, 1977, pages 27-32, with the kind permission of the author and the Department of Conservation]
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