Resource Selection by Hill Sheep: Direct Flock Observations Versus GPS Tracking

Abstract

Abstract. Uplands and peatlands are of international ecological importance and heavy grazing pressure has been implicated in a decline in their condition. Therefore, a better understanding of grazer behaviour could aid the design of conservation strategies. The objective of this study was to test whether the same resource selection results were obtained from direct flock observations as simultaneously-run GPS tracking studies. Direct flock observations were conducted on 50 sampling days, June 2004-July 2005. Habitat, habitat condition and grazing lawn frequency maps were produced. Resource use and availability were estimated using range analysis and GIS, and resource selection was analysed using weighted compositional analysis. Flock distribution was uneven with a mean of 0.0-8.9 sheep/ha observed based on a 1 ha grid system. Habitat selection based on direct observations varied seasonally with acid grasslandrelated habitats selected most in spring, summer and autumn, and wet heath and blanket bog selected most in winter. Moderately damaged areas and grid squares containing numerous/extensive grazing lawns were consistently selected most (P<0.05). Resource selection findings based on direct flock observations were consistent with those obtained using detailed GPS tracking data from fewer individuals. Resource management recommendations are discussed.

Trends, over 14 years, in the ground cover on an unimproved western hill grazed by sheep, and associated trends in animal performance

“…It is possible, however, that the negative trend recorded for some of the indicators of animal occurred in conjunction with the expansion of total vegetation in these habitats (Table 3). The significantly lower value for total vegetation frequency in wet heath than in blanket bog throughout the study period suggests a more intensive use of the former for grazing, which is consistent with the conclusions on habitat preference from a study of grazing behaviour of the flock (Williams et al, 2010). Intensive/excessive grazing, which may result in an increased extent of bare soil in this environment, is often associated with an increased occurrence of the unpalatable mat grass (Chadwick, 1960).…”

“…Williams et al (2010), using almost 8,800 field observations taken on the farm on a seasonal basis over a period of 13 mo (June 2004 to July 2005), indicated a consistent selection of the same areas on the unimproved hill for grazing during this time interval; namely, those that were classified, following the method outlined by Dúchas and DAF (1999), as moderately damaged and those that contained numerous/extensive grazing lawns -the result of intensive grazing. Furthermore, Williams et al (2010) reported that there was a higher preference for severely damaged areas in spring and summer than in other seasons.…”

“…Williams et al (2010), using almost 8,800 field observations taken on the farm on a seasonal basis over a period of 13 mo (June 2004 to July 2005), indicated a consistent selection of the same areas on the unimproved hill for grazing during this time interval; namely, those that were classified, following the method outlined by Dúchas and DAF (1999), as moderately damaged and those that contained numerous/extensive grazing lawns -the result of intensive grazing. Furthermore, Williams et al (2010) reported that there was a higher preference for severely damaged areas in spring and summer than in other seasons. Significantly, these results largely reflect those based on locational data (> 80,000 locations) from GPS ® collars, timed on a 10-min interval round the clock, which were worn by selected sheep (2 yr old and familiar with the unimproved hill) on the farm on a seasonal basis from spring 2004 to spring 2006 (Williams et al, 2009).…”

Habitat Selection by Grazing Animals in Heterogeneous Environments: The Case of Hill Sheep In Western Ireland

“…Scottish Blackface flocks are known to separate into groups (Hewson and Wilson 1979). Therefore it can be argued that the habitat selection findings were representative of the flock as was found to be the case in a concurrent study (Williams et al 2010).…”

“…The age group was selected because it had experience of the study area and was likely to survive for the duration of the 2¼-year study. Substitute ewes were tracked (Williams et al 2010) indicated no unusual social behaviour by collared ewes. However, one core ewe was a member of a small social group that chose to repeatedly jump a sheep fence (P.J.…”