Table 2. Linear mixed-effects models of the main trip parameters for nine Tawaki fitted with satellite transmitters during their pre-moult dispersal (December 2016 –February 2017).
The base model uses trip destination (Subtropical Front, STF or Subantarctic Front, SAF) as well as sex as fixed effects, and BirdID as random effect. Note that only data from birds that completed the outward-bound portion of their journey before transmitters stopped working were included in the analysis. Also note that trip duration and total trip length could only be determined for five birds.
| PARAM ~ DESTINATION+SEX+(1|BIRDID) | |||||
|---|---|---|---|---|---|
| Estimate | Std Error | DF | t | p | |
| Departure Date [days]* | |||||
| Intercept | 08-12-2016 | 4.77 | 6 | 8950.755 | <0.001 |
| Front (STF) | -11.3 | 5.34 | 6 | -2.121 | 0.078 |
| Sex (Male) | -0.7 | 5.34 | 6 | -0.128 | 0.903 |
| Max Range [km] | |||||
| Intercept | 2190.2 | 93.47 | 6 | 23.433 | <0.001 |
| Front (STF) | -745.4 | 104.49 | 6 | -7.133 | <0.001 |
| Sex (Male) | 82.4 | 104.49 | 6 | 0.788 | 0.461 |
| Daily travel distance [km/day] | |||||
| Intercept | 74.9 | 4.29 | 6 | 17.459 | <0.001 |
| Front (STF) | -11.9 | 4.80 | 6 | -2.488 | 0.047 |
| Sex (Male) | -1.6 | 4.80 | 6 | -0.326 | 0.756 |
| Trip duration [days] | |||||
| Intercept | 69.1 | 4.59 | 2 | 15.066 | 0.004 |
| Front (STF) | -0.4 | 6.49 | 2 | -0.066 | 0.953 |
| Sex (Male) | 2.6 | 6.49 | 2 | 0.396 | 0.730 |
| Trip length [km] | |||||
| Intercept | 6156.7 | 478.54 | 2 | 12.866 | 0.006 |
| Front (STF) | -1823.1 | 676.75 | 2 | -2.703 | 0.114 |
| Sex (Male) | -691.1 | 676.75 | 2 | -1.021 | 0.415 |
* Transformed to Julian Date for analysis. Intercept value has been back-transformed for clarity.