Feature

The Culling Fields

How and why should the Kaimanawa wild horse herd be managed?

Cathryn Crane

Emotion has run high and information content low in the debate over the management of the Kaimanawa wild horse herd. There have been threats of ministerial resignation and abusive phone calls to supporters of the horse culling operation chosen as the most humane and efficient population management option currently available.

Although the Department of Conservation has borne the brunt of the criticism over the Kaimanawa Wild Horse Plan, a broad range of groups were involved in discussing the benefits and liabilities of the various options explored for managing the horses. These included not the Royal Forest and Bird Protection Society, the RNZSPCA and the Kaimanawa Wild Horse Preservation Society. In addition, interested parties, such as the Rare Breeds Conservation Society and the New Zealand Ecological Society had an input.

As a consequence of this, and of the public submissions made throughout the process, a range of views and opinions were heard. According to the resulting report, the result was the identification of a number of values which could not be compromised and a number that could be catered for with compromise.

The basic agreement was that "the Kaimanawa wild horse population should not be allowed to continue to grow unchecked, especially where it compromises the indigenous environment". With this brief in mind, numerous research programmes and evaluation sessions have been conducted to look at the horses and the environment in which they exist and to examine the options available in managing the horse population in an appropriate manner.

Given the rugged nature of much of the terrain, accurate absolute population counts are difficult to obtain. A standardised aerial survey provides a chance to gain relative estimates of population changes over time. It should be noted that such surveys have been shown to consistently undercount by 10-20% the true number of animals in a given area, rather than over-estimating them as has been claimed.

Horse numbers have grown from around 530 in 1986 to 1,500 in the 1994 check. In July, DoC undertook another census, counting 1,200 in just half the range alone (the southern area which supports a higher population density). Although debates about the population size have continued, Ian Boyes of the Kaimanawa Wild Horse Preservation Society, who operated as an independent observer for the count, confirmed the tally.

From the census figures taken over the past 10 years, the horse population growth rate is estimated to be 10-24%, doubling every four years. Increased mortality from high death rates amongst foals and poor nutrition could slow that down in future; the horses may also attempt to expand their range to make up for the loss of food in an already stressed environment. DoC does not want to see the wild horses spread into nearby Tongariro National Park and the Kaimanawa Forest Park.

Intensive study of the flora and fauna of the Moawhango Ecological District under the Protected Natural Areas Programme led to nine Recommended Areas for Protection, of which four fall within the area set aside for the horses. The fragile ecosystems of the northern part of the horse range have been identified as being particularly at risk from the horses, and the population control debate has focused on that area and the horses found there. There have been no plans to "exterminate" or "annihilate" the horses in toto, as has been bruited about, as a sustainable population will be maintained in the less sensitive southern area.

Native Plants Before Introduced Horses

In commenting on the horse issue in a National Radio interview, culling opponent Ian Shearer laid the blame at the feet of botanists, both national, in the form of DoC, and international, in the person of David Bellamy.

Certainly the area is of intense interest to botanists, containing as it does 16 species featuring in the national list of threatened, rare and local plants. Research by Dr ** Rogers suggests that it also has the highest national concentration of plants with unusual and often rare occurrences, found in the North Island only within the horse range.

Many of these plants are directly threatened by the horses, being grazed or trampled by them. An adult horse requires at least 10 kilograms of dry plant matter per day; this does not take into account extra nutritional requirements for growth or reproduction.

Others are threatened indirectly when the horses open up their rather fragile habitats for invasion from undesirable weeds such as Hieracium. Seeds of introduced plants adapted for dispersal by large animals, whether through dung or in manes and tails, are spread through the area where the horses graze; indigenous plants have no such adaptations.

Effects on the physical environment, such as erosion, pugging and ground compaction, have flow-on effects for the biological, causing disruptions in water flow and downslope sedimentation and siltation. Horses tend to use the same routes through areas, causing acceleration of gully erosion and loss of soil. There is also concern about the effect of environmental modification on the native wildlife of the area, such as the large population of New Zealand falcons.

According to the plan, the "high concentration of threatened and notable species is due in part to an usual combination of features and events which have led to a number of sites supporting unusual habitats". Unfortunately for the plants these habitats, such as wetlands, are extremely vulnerable to damage and modification even by a low number of horses. Once such habitats are modified to the point of no longer supporting the unique plant life, the damage becomes ireversible, and extinction becomes a very real possibility.

One recommendation suggested that, in these vulnerable areas, horse population levels should be kept at one horse per 250 hectares, adding that the social nature of horses makes such a figure impossible to maintain.

Some critics have blamed the New Zealand Army for much of the environmental degradation by running exercises over the area and using it for target practice. What this ignores is that it is possible to control the movements of the Army and, indeed, they have put into place practices to reduce the impact of their activities on the local environment -- such as designating areas of restricted access -- as well as playing an active role in controlling the spread of invading plant and animal species in the area.

Unique Animals?

The protected area for the Kaimanawa horses was established in 1981 following a certain amount of public lobbying related to the decline in horse numbers at that time. There was no public consultation to canvass wider views, no research into the effects the protection would have on horse numbers and no research on the herd's effects on the local environment.

The Food and Agricultural Organisation listed the Kaimanawa wild horse herd on its register of biologically unique equines, and recommended a population of 1,000 animals to ensure its future viability. However, it appears unlikely that these horses actually fit any of the criteria established for inclusion on this register -- they haven't been selectively bred for any traits, they do not represent a preserved past domestic breed, they are not a true feral population without any "contamination" from outside sources. Consequently, their place on the register is being reviewed.

Suggestions of anatomical or physiological differences between the Kaimanawa horses and domestic animals have been shown to be a product of the poor nutrition of the wild horses, rather than as a result of special adaptations that would make the Kaimanawa horses unique in any fashion. Behavioural traits are also thought to be relatively consistent with those of their domestic counterparts.

As for claims that the genetics of the horses makes them unique, this has been rejected by both Massey's Equine Blood Typing & Research Centre and the Rare Breeds Society. The horses are not a distinct breed and their genetics is a melange as a result of randomly occurring releases throughout their history.

Massey research Dr Ian Anderson analysed blood samples from almost 400 horses and concluded that "the only real reasons for the retention of the Kaimanawa horses in their present environment are for historical, aesthetic or sentimental values".

The provision of the protected area and the lack of a control plan gives the horses a unique status amongst New Zealand's introduced animals -- all others such as deer, goats, rabbits and possums have some form of control operations over their population and environmental impact, including in the area under debate.

No Simple Solutions

As with most ecological issues, there are no simple solutions to the problem. In preparing the Kaimanawa Wild Horse Plan, the group had to consider a number of aspects that would affect the final management decisions:

• the level of difficulty and tine frame for implementation
• long-term effectiveness
• humaneness
• financial considerations
• availability of management tools

A range of options have been considered for the Kaimanawa horses to control their population and environmental impact in the northern part of the range. Each has positive and negative aspects. The final recommendation was for aerial shooting from helicopters as providing the most manageable and humane method of eliminating the required number of horses; following ministerial review, this was later changed to ground shooting. The horse bands average around five members apiece, so a group of marksmen would be dealing with one or two targets only in most cases.

The idea of mustering the horses and selling them off formed the main thrust of the media campaign waged by those against the culling operation. However, past attempts to do this have not produced very satisfactory results, particularly from the humane perspective. Not only were the majority of horses left to be trucked to abbatoirs, but those which were sold to private individuals had a high mortality rate, comments Peg Loague, National President of the RNZSPCA.

Attempts to break horses in were not particularly successful, with broken necks and heart attacks killing horses; one wild horse was kicked to death by domestic horses when put in the same paddock. Some never made it to their new homes -- one horse jumped from the transport and had to be shot on the side of the road after breaking tis pelvis.

The horses' lack of familiarity with other aspects of conventional control mechanisms, such as fences, presents a problem for that as an option. Damage to horses by fences and the need to monitor them to respond to any injuries is a humane concern; damage to horses by fences and the cost of erection and maintenance is an economic concern. Fencing off three of the Recommended Areas for Protection and along the Desert Road was estimated at costing up to $1 million. Some 69 kilometres of fencing would be required, which compares to Doc's entire 1994/95 national fencing effort of 71.5 km.

Immunocontraceptive approaches have strong support, but are still some time away from being useful in the field. A Massey University study investigating the effects of interfering with the natural reproductive cycle and how this affects the structure and formation of horse bands is under way, and set for completion in 1998.

At present, immunocontraceptives used overseas have limited use, requiring the mares to be inoculated every year, thus involving mustering with all its consequent problems for environmental damage and damage to the horses themselves. This becomes problematic in the rugged northern area of the horse range targeted as it appears a very high proportion of mares will need to be included in the programme for it to be successful.

Some reproductive control occurs naturally -- the 80% pregnancy rate in sampled mares compared to a field-observed 33% foaling rate at three months of age suggests significant mortality either pre- or shortly post-birth. The average foal-to-yearling survival rate is 50%, but this can vary markedly from 81% in the more supportive southern part of the range to 0% further north.

There is no doubt that the Kaimanawa wild horses are an accepted part of New Zealand's heritage, with their own intrinsic, aesthetic values. The management plan acknowledges the desirability of retaining the horses in the local area to protect and preserve the links that have developed. What needs to be recognised is that other aspects of this country's natural heritage have their own intrinsic, aesthetic values.

No plan will ever succeed in pleasing everyone, but it is necessary to ensure that any decisions that are made are made on the basis of the best facts available, rather than the best media coverage.

Cathryn Crane is a freelance journalist with an interest in environmental issues.