Design a clear educational illustration for middle-school students explaining how migratory birds navigate across a continent. Place an original simplified continent map in the center with one curved route from southern wetlands to northern nesting grounds, using small realistic bird silhouettes at several stages. Surround the route with three spacious visual callouts: a starry night cue, a daytime sun cue, and Earth magnetic field lines, connected with simple arrows and iconography. Use a landscape 4:3 classroom-poster composition on a warm light-gray background, polished flat editorial shapes, subtle dimensional shading, generous whitespace, and a navy, sky-blue, warm-yellow, coral, and muted-green palette. Keep the relationships scientifically plausible without relying on text. No readable labels, letters, national borders, logos, watermark, malformed birds, or dense decoration.