Table 3. Generalized Additive Mixed effects models with the probability of an individual seal being hauled out in each hour of a trip modelled as a binomial response.
Individual seal was a modelled as random effect with trip nested within it. AIC values are reported for the best model fit and the effect of adding (+) or removing (-) explanatory variable including different ways of grouping smoothers. Correlation was modelled by including terms of whether the seal was hauled out in the preceding hours (lag1-5). Time of year was compared using Julian day, week of year, month.
| Model terms | AIC | BIC | deviance | df.resid |
|---|---|---|---|---|
| Best model | ||||
| Hour (by month) + Latitude (by week) + Distance to land/ice (by tag) + week (by tag) + lag1 + lag2 + lag3 | ||||
| 10525.1 | 10845.9 | 10449.1 | 34222 | |
| Comparison with alternative models | ||||
| + lag4 | 10523.1 | 10853.1 | 10445.9 | 34221 |
| -lag3 | 10533.7 | 10846.1 | 10459.7 | 34223 |
| -distance to land/ice(by tag) | 10557.8 | 10817.7 | 10497.8 | 34230 |
| -'(by tag)' from 'distance to land/ice' | 10546.2 | 10821.3 | 10482.2 | 34228 |
| -'(by tag)' from 'week' | 10539.8 | 10837.7 | 10469.8 | 34225 |
| 'month(by tag)' replacing 'week(by tag)' | 10610.0 | 10930.8 | 10534.0 | 34222 |
| 'Julian day(by tag)' replacing 'week(by tag)' | 10553.7 | 10874.5 | 10477.7 | 34222 |
| -'(by tag)' from 'Latitude' | 10550.6 | 10820.8 | 10486.6 | 34228 |
| Latitude (by tag) | 10873.3 | 11118.0 | 10817.3 | 34232 |
| Latitude(by month) | 10486.6 | 10929.2 | 10378.6 | 34206 |
| hour(by Tag) | 10794.6 | 11084.9 | 10726.6 | 34226 |