A partial migrant relies upon a range-wide cue set but uses population-specific weighting for migratory timing

Table 1 Averaged model for the effects of weather variables and population on departure probability of individual blackbirds

Parameter	Estimate (β) ± SE	95% CI	p-value
Day length	− 3.65 ± 1.17	− 5.95 ± − 1.35	< 0.01
Residual ambient temperature	− 0.17 ± 0.09	− 0.34 ± 0.01	0.05
Atmospheric pressure	0.30 ± 0.12	0.06 ± 0.53	0.01
Cloud cover	− 0.42 ± 0.11	− 0.64 ± − 0.21	< 0.01
Tailwind assistance	0.29 ± 0.13	0.04 ± 0.53	0.02
Crosswind	0.59 ± 0.11	0.38 ± 0.81	< 0.01
Population (Finland) × Day length	0.73 ± 0.54	− 0.33 ± 1.79	0.18
Population (Russia) × Day length	1.95 ± 0.81	0.36 ± 3.54	0.02
Population (Poland) × Day length	1.82 ± 0.64	0.56 ± 3.08	< 0.01
Population (Finland) × Atmospheric pressure	− 0.27 ± 0.37	− 0.99 ± 0.45	0.46
Population (Russia) × Atmospheric pressure	− 0.36 ± 0.37	− 1.08 ± 0.36	0.33
Population (Poland) × Atmospheric pressure	1.00 ± 0.40	0.21 ± 1.79	0.01
Population (Finland) × Cloud cover	0.38 ± 0.44	− 0.48 ± 1.24	0.39
Population (Russia) × Cloud cover	− 0.74 ± 0.31	− 1.33 ± − 0.14	0.02
Population (Poland) × Cloud cover	− 0.29 ± 0.46	− 1.19 ± 0.60	0.52
Population (Finland) × Tailwind assistance	0.37 ± 0.28	− 0.17 ± 0.92	0.18
Population (Russia) × Tailwind assistance	1.31 ± 0.44	0.44 ± 2.17	< 0.01
Population (Poland) × Tailwind assistance	0.11 ± 0.27	− 0.42 ± 0.64	0.68
Population (Finland) × Crosswind	− 0.63 ± 0.25	− 1.12 ± − 0.14	0.01
Population (Russia) × Crosswind	− 0.29 ± 0.39	− 1.05 ± 0.47	0.45
Population (Poland) × Crosswind	− 1.28 ± 0.30	− 1.86 ± − 0.69	< 0.01

Adjusted Akaike’s Information Criterion (AICc) has been used to determine the final candidate models (Additional file 1: Table S1)
Average model estimates, adjusted standard errors (SE), 95% confidence intervals (CIs) and associated p-values of parameters included in the candidate models. p-values ≤ 0.05 are given in bold font. The reference category for species is the German population

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