🗓️ Migration Timing Reference Chart

A general reference for typical North American migration windows. Exact timing varies significantly by latitude, species, and yearly weather — check regional birding resources for local peak dates.

How the nine windows fit together

Read down the chart and it maps a year rather than a season. Spring builds in three steps — waterfowl and blackbirds from late February, sparrows and early warblers through April, then the late April to mid May peak for warblers, thrushes and vireos — while shorebirds run April into late May alongside it.

Autumn is the half people misjudge. The chart opens it in July with early shorebird passage, weeks before the September to early October songbird peak; hawk watches then cover September to November and waterfowl carry the movement through to December. The windows overlap heavily, and only late June and early January are genuinely quiet on this list.

Turning a continental chart into local dates

Latitude moves everything. A window that fits the southern edge of the continent can be two to four weeks out at the northern end, in opposite directions for spring and autumn.
Weather decides the nights. Within any window most movement arrives on a few nights behind favourable winds, so a fortnight of nothing followed by one busy morning is normal rather than a failed forecast.
Check something local and current. Regional bar charts, local alerts and nightly migration forecasts give dates for your county; this chart gives the shape of the year.

These are general North American windows and the page cites no source for them. They vary by region, by latitude and from one year to the next, and they say nothing about which species occur where you are. Treat them as a planning outline, not a prediction for your patch.

Frequently asked questions

When is peak spring migration for warblers?

Late April to mid May on this chart, which covers North America as a whole. Your own peak may sit noticeably earlier or later depending on how far north you are, so check a regional bar chart for the county.

When does fall bird migration start?

Earlier than most people expect: the chart puts early shorebird passage in July and August, ahead of the September to early October songbird peak and the October to December waterfowl movement.

Does this chart work outside North America?

No. The windows are drawn for North America, and timing elsewhere follows different routes and seasons entirely. Use a chart or checklist compiled for your own region instead.