Table 3 Significant results of GLMMs from the best supported models showing the effects of NDVI, tree cover, tailwind (all centered and standardized [78]) and season on migration speeds, with individual and year as crossed random factors for a) all GPS telemetry based segments, b) excluding transitioning segments between day and night and including day vs. night as a fixed factor along with its interactions with the other predictors, and c) comparing day and night again, but this time focusing just on active movements (migration speeds >5 km/h). (Full list of candidate models and results from full models and models within ΔAICc <4 in Additional file 1, Table S3, S4, S5)
| Â | Estimate | SE | t | P |
|---|---|---|---|---|
a) All GPS telemetry locations (N = 1435) | ||||
 Intercept | −0.02 | 0.11 | −0.19 | 0.86 |
 NDVI | −0.34 | 0.03 | −13.52 | <  0.001 |
 Tree cover | −0.08 | 0.03 | −2.52 | <  0.05 |
 Season | −0.22 | 0.08 | −2.87 | <  0.01 |
 Tailwind: season | −0.22 | 0.06 | −3.45 | <  0.001 |
b) GPS telemetry locations excluding transitions between day and night (N = 984) | ||||
 Intercept | 0.46 | 0.13 | 3.65 | < 0.05 |
 Day/night | −0.89 | 0.06 | −14.67 | < 0.001 |
 NDVI | −0.33 | 0.03 | −11.10 | < 0.001 |
 Season: day/night | −0.44 | 0.13 | −3.34 | < 0.001 |
c) Active movements only (N = 465) | ||||
 Intercept | −0.19 | 0.20 | −0.94 | 0.35 |
 Day/night | 0.70 | 0.15 | 4.81 | < 0.001 |
 Tailwind | 0.10 | 0.05 | 2.06 | < 0.05 |
 NDVI | −0.26 | 0.04 | −5.97 | < 0.001 |
 Tree cover: day/night | −0.30 | 0.10 | −2.85 | < 0.01 |
 Season: day/night | −1.13 | 0.30 | −3.73 | < 0.001 |