During which periods can a birder have a higher probability of encountering a Wryneck in transient areas like Southern Europe during April or September?

During the spring and autumn migration periods along known flyways.

Observing the Wryneck can sometimes be easier during its migratory phases—spring and autumn—than when it is settled on its breeding grounds or wintering sites. This heightened detectability occurs because the concentrated movement forces large numbers of these typically dispersed birds into predictable corridors, known as flyways. For example, a birder positioned along a known path in Southern Europe, such as near Malaga, during April or September, has a statistically higher chance of spotting a Wryneck passing through. These migration periods create temporary hotspots where the species is present in higher densities as they move sequentially through specific points across their range, contrasting with the more sparse distribution found when they are settled for breeding.