Can Home Range be Used as an Identifier of Lambing for Grazing Pregnant Merino Ewes?

Abstract

Lamb survival is a critical issue within sheep flocks (Alexander 1986). Therefore, understanding grazing pregnant ewe behaviour before, during and after lambing could help reduce lamb losses. Devices such as global positioning systems (GPS) have the potential to remotely monitor behavioural indicators that could be used to identify the onset of lambing. Such indicators could then be used to help improve lamb survival. Taylor et al. (2011) reported how GPS tracking devices helped in understanding grazing pregnant Merino ewes use of shelter at lambing. An alternative behavioural indicator that could be used is the animal's home range as its size, location and shape may change depending on the physiological state of the individual and environmental conditions. Many of the statistical methodologies to estimate home range have their origin within wildlife and endangered species research. It is unknown if these statistical methods would be suitable to identify changes in ewe behaviour within small paddock sizes.