It is one of nature's miracles: right now, several million small birds are on their way from Africa to the UK, and all under their own steam without the benefits of combustion or jet engines, and without burning fossil fuels!
Born here either last year or in the couple of years before that, they will have headed south last autumn to escape our winter, and now the hardwiring in their brains is telling them it is time to make the treacherous journey back home.
They tend to take their journey here in stages, for a journey of 3000 miles or more is something few can do in one leap. For many, it will mean crossing the Sahara, navigating across the Mediterranean, and some will fly over the entire Bay of Biscay to get here.
But the thing that makes it very personal to each of us is that, on the last big leg of the journey that brings them to the British isles, some will touch down in our gardens; in YOUR garden. What a privilege to see a bird that has just completed the most epid of marathons.
It means that a bird that a couple of weeks ago would have been refuelling at an oasis in the middle of the desert is now flitting around your bushes and borders. Where one day your birdsong was just the resident Blackbirds, Robins, Dunnocks and Wrens, now new melodies join the chorus.
Different migrant species tend to return at slightly different times, so we await each of them in turn. So, for example, the first to arrive back is often the Chiffchaff, from early March onwards. They are barely the size of a Blue Tit, plain and olive-coloured in plumage, with a fine bill perfect for catching insects, so it is the metronomic 'chiff chaff chiff chaff' song that is likely to first grab your attention. They like to sing from 5m (15 ft) or so up in the bare branches of a spring hazel or willow tree, and it is a sound that signals spring is definitely underway.
By late March, they are joined by Blackcaps, first the males which indeed have black caps, and then the ginger-capped females.
Confusingly, their arrival may cross-over in dates with the increasing numbers of Blackcaps that winter here and which are thought to mainly come from breeding grounds in Germany and neighbouring countries. Both our incoming males and those German birds about to leave may burst into song. It is very beautiful, with each verse tending to start with a stutter and then break into pure, fluty notes, rich and flowing.
By late March, the first Willow Warblers make landfall. Almost identical to Chiffchaffs by sight, they are usually rather brighter and yellower in colour, but it is again their song which picks them out, for it is the sweetest, gentlest of cascades, which conjures in my mind a vision of a pirouetting ballerina gently descending a staircase.
These three species are the most likely to pass through gardens, although if you have a larger or more rural or coastal garden, there is a host of other warblers, plus flycatchers and even the Cuckoo, that might then pass through during April and May.
So what can you do to prepare your garden for them?
Well, all these birds are unlikely to visit your birdfeeders (although our wintering Blackcaps are very enterprising and have learned to take fat and even seeds from birdfeeders). Instead, what these migrants are looking for are insect-rich habitats where they can feed. An open garden dominated by lawn or hard surfaces is no use to them; they want a garden that is ringed with shrubs and bushes, with the odd tree poking up through them, but where the sun pours down into the middle. A sunny glade - that's the key, and maybe this year you can rejig your garden a little to create that look, for it is one of the best for all manner of wildlife.
Here is a Chiffchaff that couldn't resist a quick freshen up in my pond a couple of springs ago, and no wonder after a long, tiring journey.
Come April, another band of migrants will appear in the skies above: the Swallow and the House Martin, followed in May by the Swift. But for now, keep your eyes - and ears - trained on your garden itself. Should you see one of these wanderers, then cheer their return, and marvel at their achievements.
If you want to drop by my RSPB wildlife gardening blog, it is updated every Friday, and I'd love to see you there - www.rspb.org.uk/community/blogs/hfw
I was delighted to hear the Chiff Chaff on Wednesday, 27th February along the canal near Slimbridge. It seems early this year.