Spring migration is the easiest time of the year to add new species to your list. Birds that wintered south are moving back to breeding grounds, and many of them stop briefly in places they would never visit in summer. Even an ordinary city park can host a dozen species in early May that are absent the rest of the year.
When it happens
The peak depends on latitude and species. In western Europe, the busiest weeks are mid-April to mid-May. In eastern North America, late April through the third week of May. The wave moves north — what arrives in southern France in April reaches Scotland in May.
The weather matters. After a clear night with a warm southerly wind, expect heavy arrivals at dawn — birds travel overnight and drop in to feed at first light. After several days of cold north winds, arrivals stall and the same locations look empty.
Species to watch for
Warblers are the prize for many migration watchers. They are tiny, often colourful, sing constantly when they arrive, and only pass through most areas for a few days. In Europe: chiffchaffs and willow warblers (almost identical-looking, very different songs), blackcaps, and garden warblers. In North America: yellow-rumped, black-throated green, and yellow warblers in their loud spring plumage.
Swifts and swallows are the easiest migrants to notice — they reappear in the sky almost overnight, usually around the last week of April. The first swift over your house each year is a small but reliable seasonal marker.
Where to look
Migrant birds look for food and shelter, not for picturesque settings. Coastal headlands, river valleys, and any patch of trees in an otherwise open landscape are productive. In cities, large parks with mature trees and undisturbed corners outperform manicured gardens.
Mornings are vastly better than afternoons. Birds that arrived overnight are hungry and active for the first two or three hours after sunrise, then quieten down for the day. If you only have one window of time, set the alarm and skip the late lunch.