This book arrived three days before the swifts returned to the skies above Somerset.  When I unwrapped the tissue-packed parcel, I was captivated by the cover – Jonathan Pomroy’s illustrations are so evocative of the drama and vertiginous speed of these remarkable, ancient birds.

The Screaming Sky is a book born of an obsession.  On his own admission, Charles Foster is obsessed with swifts – where others might be content to watch them in the skies over Oxford, and be blessed by their occupation of nest sites in the roof of his house, Foster travels on pilgrimage to see them in Spain, Greece and Israel, as well as in the tropical heat and humidity of their African winter homes.  He tracks the progress of their migrations via other obsessives on the internet, and the swifts’ presence or absence in the air above him is mirrored in the highs and lows of his mood.  It is as if he cannot live without them.

This gorgeously tactile little book is divided into monthly chapters, January to December.  In each chapter, Foster explores what the swifts are doing that month, and where, as well as delving into the history, biology and statistics of these enigmatic creatures.  We know quite a bit about Apus apus, the Common Swift.  For example, they spend most of their lives on the wing, landing only to breed and occasionally when encountering very bad weather during migration.  They sleep while flying – the two halves of the brain take it in turns to sleep.  Following the cornucopia of insect life (what Foster refers to as aerial plankton or krill), they migrate inconceivable distances – the swifts breeding in Foster’s summertime Oxford spend the winter months 6,000 miles south in Mozambique.   They lay up to four eggs, but the fourth hatchling (if there is one) never survives.  Young swifts set off for their winter homes within weeks, sometimes days, of fledging. 

We know that swifts are truly ancient, having evolved over 30 million years ago. Swifts are also long-lived – they can have a lifespan of 20+ years.  They return to the place where they were hatched, spending their first couple of summers screaming around the sky with their companions and generally, it seems, having a ball, maybe even tentatively pairing up, before scoping out a potential nest site for the serious business of claiming a nest and breeding.  We know that most of the birds which travel to western Europe for the summer breeding season spend a while over Liberia, gorging on the insect soup swirling in the air after the rains.  From there, the swifts I see in Somerset will have travelled some 3,100 miles, in as little as five days.

However, there is so much we don’t know about swifts.  There are myriad theories, for example, about how they navigate over these immense distances, how they decide that the time is right to start their migration, how they re-unite with their mate, and what accounts for the wide variations in how long it takes individual birds to make the journey.

Foster explores the place of the swift in literature, the emphasis on the bird’s speed (the clue is in the name) and its totemic role as the essence of the northern European summer.  He also rails against the appropriation of the swift as somehow the possession of the observer.  Swifts, he says, are not ‘yours’ or ‘mine’ or ‘his’.  They are their own selves, untameable, masters of the sky in a way that we can only dream of, and in no way reciprocating the sense of connectedness we feel with the swifts who condescend to make fleeting use of our roof-eaves and insect supplies.  It is this unconquerable wildness which, for Foster (and for me) makes swifts so compelling.

Perhaps more than anything, though, he is full of admiration for their mastery of their environment, the sky: ‘they inhabit the air as fish inhabit the sea’.  Their speed and seemingly effortless command of the tides of the air is not only functional (hunting insects) but also seems to have a powerful element of fun and joy: ‘not everything is about the algorithms of survival’ and the screaming parties of swifts hurtling through the sky are ‘colossal fun’.

I love this book.  The blend of facts and personal enthusiasm for the subject makes it an engaging read, and Jonathan Pomroy’s illustrations are perfect.  Of course, I loved it all the more – and was so excited when I heard that Little Toller Books were going to be publishing it – because of how I feel about swifts.  The sight of those exuberant little black sickles slicing through the late spring sky at the end of their epic migration is viscerally energising.  Shrieking squadrons, skimming just over my head between the red-brick cliffs of the town houses, sound so intensely full of life that they make me feel alive, too.  And the day in August when suddenly the sky is silent, empty of little black sickles as they follow the call of their African winter home, is the day the year turns towards winter for me, too.

The Screaming Sky by Charles Foster, illustrated by Jonathan Pomroy, is published by (and available from) Little Toller Books, 2021.  ISBN 9781908213846