Distribution of field birth-sites of lambing ewes

Summary. This paper reports on birth-site distribution of Merinos and some British breeds in 34 lambing paddocks in a major study over 5 lambing seasons at Armidale New South Wales, and in minor studies during single lambing seasons, 2 in New South Wales and 3 in the United Kingdom. The observed distribution of birth-sites is related to topographic and other environmental features of the paddocks. In level, or nearly level paddocks, Merinos tended to lamb in a random pattern, but in sloping paddocks their birth-sites were consistently aggregated in the areas of greatest elevation. British breeds (Suffolks and Cheviots in New South Wales, and Welsh Mountain, Scottish Blackface, North Country Cheviots and Greyface in the United Kingdom) showed a pronounced tendency to lamb near the margins of paddocks, and a less marked preference for an elevated site. It is suggested that lamb mortality could be significantly reduced by the use of paddocks that provide shelter at preferred elevated positions, or along and within the paddock margins.