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. 2012 Nov 28;7(11):e50611. doi: 10.1371/journal.pone.0050611

Table 2. Sets of models predicting group vigilance and scan frequency in elk.

Model # Dep. variable: arcsine square root [group vigilance], n = 424 elk groups AIC ΔAIC wi ER logLik
1 ln[herd size]+land-use/season+dist. nearest tree cover + dist. nearest road (≥12 vehicles per day) 118.6 0 0.9003 1 −45.3
2 ln[herd size]+land-use/season+dist. nearest road (>12 vehicles per day) 124.2 5.6 0.0547 16 −49.1
3 ln[herd size]+land-use/season+ dist. nearest road (>12 vehicles per day)+Terrain ruggedness 125.4 6.8 0.0301 30 −48.7
4 ln[herd size]+land-use/season+ dist. nearest road (>12 vehicles per day)+wolf RSF+grizzlybear RSF 127.0 8.4 0.0134 70 −48.5
5 ln[herd size]+land-use/season+dist. nearest tree cover 131.3 12.7 0.0015 600 −52.7
6 ln[herd size]+land-use/season 141.7 23.2 <0.0001 105 −58.9
7 ln[herd size]+land-use/season+ wolf RSF+grizzly bear RSF 142.3 23.7 <0.0001 105 −57.2
8 ln[herd size]+land-use/season+ Terrain ruggedness 143.7 25.2 <0.0001 105 −58.9
9 ln[herd size]+dist. nearest road (>12 vehicles per day) 190.7 72.2 <0.0001 1015 −89.4
10 ln[herd size]+dist. nearest tree cover 203.2 84.6 <0.0001 1018 −95.6
11 ln[herd size] 203.9 85.3 <0.0001 1018 −96.9
12 ln[herd size]+Terrain ruggedness 205.2 86.6 <0.0001 1018 −96.6
13 ln[herd size]+wolf RSF+grizzly bear RSF 206.4 87.8 <0.0001 1019 −96.2
14 Intercept only 379.5 261.0 <0.0001 1056 −185.8
Model # Dep. variable: ln[scan frequency +1], n = 870 focal elk AIC ΔAIC wi ER logLik
1 ln[herd size]+land-use/season + dist. nearest road (≥12 vehicles per day) 75.3 0 0.9476 1 −24.7
2 ln[herd size]+land-use/season+inter-individual distance 81.9 6.5 0.0361 26 −27.9
3 ln[herd size]+land-use/season+wolf RSF+grizzly bear RSF 84.5 9.1 0.0098 97 −28.2
4 ln[herd size]+land-use/season+ dist. nearest tree cover 87.6 12.3 0.0020 464 −30.8
5 ln[herd size]+land-use/season 88.1 12.8 0.0016 587 −32.0
6 ln[herd size]+land-use/season+age/sex class 88.6 13.3 0.0012 758 −30.3
7 ln[herd size]+land-use/season+within-group position 89.3 13.9 0.0009 1062 −31.6
8 ln[herd size]+land-use/season+Terrain Ruggedness 89.8 14.5 0.0007 1396 −31.9
9 ln[herd size]+dist. nearest road (≥12 vehicles per day) 173.4 98.1 <0.0001 1021 −80.7
10 ln[herd size]+wolf RSF+grizzly bear RSF 190.9 115.6 <0.0001 1025 −88.5
11 ln[herd size]+age/sex class 191.7 116.3 <0.0001 1025 −88.8
12 ln[herd size]+inter-individual distance 194.8 119.5 <0.0001 1025 −91.4
13 ln[herd size]+dist nearest tree cover 195.9 120.5 <0.0001 1026 −91.9
14 ln[herd size] 197.4 122.0 <0.0001 1026 −93.7
15 ln[herd size]+Terrain Ruggedness 199.0 123.7 <0.0001 1026 −93.5
16 ln[herd size]+within-group position 199.3 124.0 <0.0001 1026 −93.7
17 Intercept only 315.4 240.1 <0.0001 1052 −153.7

Two sets of linear mixed models fit to predict group vigilance (upper panel) and scan frequency (lower panel) in elk observed in SW Alberta, Canada. Best models (in bold, first rows) explained 83% of the variability of group vigilance and 86% of variability of scan frequency, respectively, as approximated by a likelihood ratio RLR 2. [AIC = Akaike information criterion; ΔAIC = difference in AIC value between the AIC of a given model and the best model (lowest AIC); wi = Akaike weights; ER = evidence ratio; logLik = log-likelihood value].