The Organisation of Possum Control

The basis for successful possum control is adequate legislation - the Wildlife Act of 1953 contains in its sixth schedule a list of animals "declared" to be noxious (and hence to be destroyed) under the Noxious Animals Act of 1956. This list includes nine species of deer (Cervidae), thar Hemitragus jemlahicus, chamois Rupicapra rupicapra, goat Capra hircus, pig Sus scrofa, wallabies (Macropodidae) and the possum. Local efforts at the control of any of the so declared species vary markedly throughout New Zealand, but in terms both of the finance and control effort expended, the possum is now pre-eminent.

Two organisations are involved in possum control. The Agricultural Pests Destruction Council (APDC) with its associated pest boards is responsible for the control of possums on all rateable lands, while the New Zealand Forest Service (NZFS) is similarly charged on lands of other tenure, e.g. state forest, unoccupied crown lands, national parks and flora and fauna reserves.

The involvement of the APDC and of its predecessor, the Rabbit Destruction Council (RDC) in possum control began in 1958. Initial action was taken by the Banks Peninsula and Northern Hawkes Bay Pest Boards, who became alarmed at possum densities on local farmland and mounted pilot control programmes funded by direct government grants. The success of these operations, together with the concern growing for the numbers of possums present over much of New Zealand's rateable land, led in 1960 to an amendment of the Rabbit Act of 1955. Boards then became able through revised legislation, to legitimately seek revenue both from central government and from rate payers for the control of possums wheresoever they are declared "a pest of local importance". Many boards made use of this amendment - 61 had done so by 1962, and 87 out of a total of approximately 100 by August 1976 (Fig. 2). Surprisingly, possums have been declared "pests" in areas where the nature of the farmland and land management is such that the species is unlikely ever to cause serious economic losses, viz. boards in inland South Canterbury and Central Otago. Conversely, other boards exist which have yet to declare the possum a pest, even though they are contiguous with, or are themselves, thought to be harbouring Tb infected populations, viz. South Otago, Waitomo and Hutt.

The involvement of the NZFS in substantial possum control began with sodium monofluoroacetate (compound 1080) trialsin 1956 in the Aorangi, Granville and Mt Bruce indigenous forests and Ngaumu exotic plantings. Subsequent control has been confined largely to populations in indigenous forests and page 214

Fig. 2 Pest destruction districts which have yet to declare the possum a "pest of local importance" (cross-hatched areas). Data from the Agricultural Pests Destruction Council 'Bulletin to Pest Destruction Boards'.

exotic plantings within state forests, with the exception that since the early seventies and the isolation of bovine Tb from possums, some control of diseased populations on rateable lands has taken place. Involvement of the NZFS in control on rateable lands has resulted from (1) the absence of active pest boards in key Tb areas, particularly the Buller, Inangahua and Grey counties, (2) the need to control possums on non-rateable forested lands contiguous with lands of other tenure and, (3) the control experience gained in past years by its management staff.