Table 3.
Models evaluated and selection results for generalized linear mixed models used to evaluate factors influencing exposure to C. burnetii, T. gondii, and Brucella spp. of adult (≥5 yrs old) and subadult (2–4 yrs old) polar bears captured on the coast and sea ice of the southern Beaufort Sea, Alaska, USA, 2007–2014.
| Pathogen | Models | K | AICc | Δ AICc | Akaike Wt. (w i) |
|---|---|---|---|---|---|
| C. burnetii | intercept + age | 3 | 174.74 | 0.00 | 0.26 |
| intercept + age + sex | 5 | 175.61 | 0.87 | 0.17 | |
| intercept + year of capture | 9 | 175.97 | 1.23 | 0.14 | |
| intercept + sex | 3 | 176.24 | 1.50 | 0.12 | |
| intercept + age + habitat use | 5 | 176.82 | 2.08 | 0.09 | |
| intercept + habitat use | 3 | 177.57 | 2.83 | 0.06 | |
| intercept + sex + habitat use | 5 | 177.92 | 3.18 | 0.05 | |
| intercept + year of capture + habitat use | 11 | 178.04 | 3.30 | 0.05 | |
| intercept + year of capture + habitat use + sex + age | 15 | 178.42 | 3.68 | 0.04 | |
| T. gondii | intercept + habitat use | 3 | 153.80 | 0.00 | 0.39 |
| intercept + sex + habitat use | 5 | 154.92 | 1.12 | 0.22 | |
| intercept + age + habitat use | 5 | 155.20 | 1.40 | 0.19 | |
| intercept + year of capture + habitat use | 11 | 155.83 | 2.03 | 0.14 | |
| intercept + year of capture + habitat use + sex + age | 15 | 158.06 | 4.26 | 0.05 | |
| intercept + age + sex | 5 | 171.42 | 17.62 | <0.01 | |
| intercept + sex | 3 | 172.80 | 19.00 | <0.01 | |
| intercept + age | 3 | 174.74 | 20.94 | <0.01 | |
| intercept + year of capture | 9 | 175.97 | 22.17 | <0.01 | |
| Brucella spp. | intercept + sex + habitat use | 5 | 118.75 | 0.00 | 0.17 |
| intercept + year of capture + habitat use | 11 | 119.18 | 0.43 | 0.14 | |
| intercept + sex | 3 | 119.22 | 0.47 | 0.14 | |
| intercept + habitat use | 3 | 119.53 | 0.78 | 0.12 | |
| intercept + year of capture | 9 | 119.55 | 0.80 | 0.11 | |
| intercept + age | 3 | 119.87 | 1.12 | 0.09 | |
| intercept + year of capture + habitat use + sex + age | 15 | 120.18 | 1.43 | 0.08 | |
| intercept + age + sex | 5 | 120.37 | 1.62 | 0.07 | |
| intercept + age + habitat use | 5 | 120.93 | 2.18 | 0.06 |
Akaike’s Information Criterion corrected for small sample size (AICc) and ΔAICc were used to identify top model sets. Normalized Akaike weights (w i) were used to assess individual model information content (models with ΔAICc values ≤2.0 were considered to provide similar levels of empirical support).