;2006;2007;2008;2006–08 "Average distance (km) between nearest neighbours of all active hollows";"0.18 ± 0.29";"0.13 ± 0.16";"0.15 ± 0.26";"0.13 ± 0.24" Range;0.03–1.23;0.03–0.79;0.03–1.13;0.03–1.2 "Average distance (km) between nearest neighbour laid in a particular week or the previous week";"1.05 ± 1.02";"1.04 ± 1.24";"0.60 ± 0.76";"0.86 ± 0.99" Range;0.15–3.04;0.13–3.08;0.15–3.10;0.13–3.10