Table 4. Results of selection of mixed-models exploring the effect of sex, age, social status, and month on fecal cortisol metabolites levels in two wolf packs from Yellowstone National Park (USA), 2007–2009.
Only candidate models with ΔAICc < 10 are shown.
| Fixed-effects parameters a | k | log likelihood | AICc | ΔAICc | w |
|---|---|---|---|---|---|
| null | 5 | -206.1 | 423.3 | 0 | 0.45 |
| social status | 6 | -205.9 | 425.4 | 2.10 | 0.16 |
| sex | 6 | -206.0 | 425.8 | 2.43 | 0.13 |
| month | 8 | -204.1 | 427.1 | 3.80 | 0.07 |
| sex + social status | 7 | -205.9 | 428.0 | 4.65 | 0.04 |
| age | 7 | -205.9 | 428.1 | 4.73 | 0.04 |
| age + social status | 8 | -204.9 | 428.8 | 5.49 | 0.03 |
| month + social status | 9 | -203.8 | 429.5 | 6.12 | 0.02 |
| month + sex | 9 | -204.1 | 429.9 | 6.60 | 0.02 |
| sex + social status + sex x social status | 8 | -205.8 | 430.6 | 7.27 | 0.01 |
| age + sex | 8 | -205.8 | 430.7 | 7.35 | 0.01 |
| age + sex + social status | 9 | -204.9 | 431.6 | 8.31 | 0.01 |
| month + sex + social status | 10 | -203.8 | 432.4 | 9.02 | 0.00 |
| age + month | 10 | -204.0 | 432.7 | 9.36 | 0.00 |
k: number of estimable parameters; AICc: Akaike Information Criteria adjusted for small sample sizes; ΔAICc = (AICc)–(AICc)min; w: Akaike weight.
a All models were fitted with a random intercept for individual identity nested within pack identity, and a random intercept for winter of sample collection.