One December, in midsummer South Africa, Tim Dee was watching swallows. They were at home there, but the same birds would soon begin journeying north to Europe, where their arrival marks the beginning of spring. Between the winter and the summer solstice in Europe, spring moves north at about the speed of swallow flight.

That is also close to human walking pace. In the light of these happy coincidences, Greenery recounts how Tim Dee tries to travel with the season and its migratory birds, making remarkable journeys to keep in step with the very best days of the year, the time of buds and blossoms and leafing, the time of song and nests and eggs. After South Africa, we follow European migrants staging in Chad and Ethiopia, and on across the colossal and incomprehensible Sahara.

We accompany storks venturing the Straits of Gibraltar, honey buzzards dodging Sicilian hunters, and tiny landbirds finding haven on the curious island of Heligoland. A diary of the spring spreading through Britain with a magic trinity of oak-tree-loving birds interleaves the continental greening. We read of other determined spring-seekers:

DH. Lawrence and Samuel Taylor Coleridge. We hear from a Sami reindeer herder, a barn-dwelling swallow-devotee, an Egyptian taxi driver, a chronobiologist in arctic Norway.

There are bears and boars and bog-bodies too. Greenery is a masterpiece of nature writing, deeply informed, expansive and often profoundly beautiful. Tim Dee's journey ends where the greenery of the European spring ends: on the shores of the Arctic Ocean in northern Scandinavia, where, yes, there are swallows in midsummer as there were at the Cape of Good Hope in December