Use of global positioning system collars to monitor spatial-temporal movements of co-grazing goats and sheep and their common guardian dog

Abstract

Goats and sheep often graze together and guardian dogs are commonly used for protection from predators. The objective of this experiment was to characterise how goats, sheep and guardian dogs interact spatially when grazing the same pasture by use of global positioning system (GPS) collars as an unobtrusive means of behaviour monitoring. In 2002 and 2003, three meat goats and two sheep in a group of 12 of each species were randomly chosen and, along with a guard dog, fitted with GPS collars. Minimum distance travelled between consecutive 30-min fixes and distance between any two animals at the same fix time were calculated using spherical geometry. In 2002, the dog travelled the least between fixes during the day but more at night than either goats or sheep. However, in 2003, there was not a significant species difference in distance travelled in 24 h or during the day or night. All species travelled significantly more during day than night but none were stationary at night. Distance amongst goats and between sheep tended to be greater during day than night; distance between goats and sheep was greater than the distance amongst goats or between sheep. Hence, goats and sheep interacted as two separate entities rather than as one large herd/flock. Distance between the dog and goats was closer than between the dog and sheep, indicating a clear preference of the dog for goats that could relate to a difference in previous exposure to the two species. In summary, based on these findings protection by a guardian dog would be greater for a small group of goats than sheep and much greater than for a mixed species group. Or, with a large group of grazing animals, the number of dogs required for a certain level of protection would rank goats < sheep < mixture of goats and sheep.

Keywords:

• goats
• sheep
• GPS
• guardian animal
• spatial behaviour

Acknowledgements

This research was supported in part by Research Grant No. LS01-119 from the USDA Sustainable Agriculture Research and Education programme.