Table 2.
Results of mixed‐models testing for the effects of wintering region on arrival date, lay date, egg volume, proportion of godwits breeding in the good quality habitat (herb‐rich meadows) of black‐tailed godwits wintering either north or south of the Sahara
| Response variables and random effects | Predictors | Estimate | SE | p |
|---|---|---|---|---|
| (a) Arrival date (counted from 1 March) | Intercept | 3.186 | 0.050 | <.01 |
| Wintering region | −0.122 | 0.040 | <.01 | |
| Sex | −0.112 | 0.040 | <.01 | |
| Wintering region × sex | −0.032 | 0.079 | .69 | |
| Individual | 0.232 | 0.020 | <.01 | |
| Year | 0.103 | 0.035 | <.01 | |
| Residual | 0.393 | 0.011 | <.01 | |
| (b) Laying date (counted from 1 April) | Intercept | 3.236 | 0.047 | <.01 |
| Wintering region | −0.238 | 0.056 | <.01 | |
| Individual | 0.241 | 0.028 | <.01 | |
| Year | 0.079 | 0.036 | <.01 | |
| Residual | 0.286 | 0.018 | <.01 | |
| (c) Egg volume | Intercept | 41.296 | 0.329 | <.01 |
| Wintering region | −1.194 | 0.451 | <.01 | |
| Lay date (centered) | −0.010 | 0.014 | .49 | |
| Wintering region × lay date | 0.039 | 0.273 | .19 | |
| Individual | 2.457 | 0.175 | <.01 | |
| Year | 0.338 | 0.184 | .01 | |
| Residual | 1.408 | 0.085 | <.01 | |
| (d) Proportion breeding good habitat | Intercept | 0.870 | 0.124 | <.01 |
| Wintering region | 0.087 | 0.193 | .65 | |
| Sex | 0.270 | 0.191 | .16 | |
| Wintering region × sex | −0.629 | 0.390 | .11 |
Reference level for wintering region is “north of Sahara” and “female” for sex. Variables removed from the final model are in italics. Arrival and lay dates were log‐transformed, and breeding habitat and nest success are on a logit scale. Random effect estimates refer to standard deviations.