Lamb predation in Australia: incidence, predisposing conditions, and the identification of wounds

Abstract

Surveys of neonatal lamb mortality show that neither disease nor predation is reponsible for most of the losses, although in certain flocks these factors may cause severe damage. Nearly half of the lambs are starving at death and this suggests a breakdown in the mother-offspring relationship. The pertinent aspects of ewe and lamb behaviour and physiology are discussed and the predisposing conditions for predation are defined as: (1) faulty nutrition of the ewe during pregnancy, resulting in prolonged labour; (2) climatic stress during and after parturition. The species involved in lamb predation and carrion feeding are discussed in relation to the role played by these animals in neonatal lamb mortality. The need to distinguish between the predation of healthy lambs, the predation of sick and weakly lambs, and the eating of carrion is emphasized. Wounds made by Australian carnivorous animals, on both live and dead lambs, are described and a key to lamb-wound identification included. Appendix I describes the technique of lamb autopsy and the assessment of lamb viability. Appendix II gives an example of the use of this method in the analysis of predation in two flocks. Appendix III discusses the terminology relevant to predators and predation.