Flyway — did the weather move the birds?

Flyway Did the weather move the birds? Bird migration and wind in eastern Canada.

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Grey cell: fewer than 5 bird records, too few to tell.
No cell: nobody reported a bird there. That is not the same as no birds.
Arrows: wind about 750 m up during the previous night, pointing where the air is going. Most songbirds migrate at night at that height.

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Bars: Strip below the bars: night wind over the whole region, green when it pushes birds along their seasonal direction (south in fall, north in spring), red when it holds them back.

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Answers are written from the observations and weather shown here, with the figures and sources behind them.

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What do these words mean?

Checklist: The list of birds one observer or group reported to eBird for one outing, with its duration and distance.
Complete checklist: A checklist where the observer reported every species detected. Only then does a missing species mean it was looked for and not found.
Reporting rate: The share of complete checklists on which a species or group appears. It does not grow just because more people were out.
Research grade: An iNaturalist observation whose identification was confirmed by other members.
Tailwind: Wind blowing in the direction the birds are travelling: south in fall, north in spring. A headwind blows against them.
925 hPa: A pressure level about 750 m above the ground, the height at which most songbirds migrate at night.
Confidence: Computed from the data, not chosen by the language model: it drops when records are few, recent days are still filling up, or the weather is a forecast.