Which book? Swifts and Us, by Sarah Gibson is full of little known facts about the birds that sleep in the sky and that are now back with us for an all too short three months. So did you know (I didn’t)?
* Back in the day (i.e. geological time), swifts and hummingbirds share a common ancestor. Despite appearances, swifts are classified into different bird families from swallows and martins.
* Also back in the day (nearer to our day), swifts were the object of superstition and even fear because they seemed so mysterious. Hence, country names such as devling, sker-devil and black imps.
* Swifts mate on the wing, the only bird species to do so. Is it quick? It’s certainly swift, and sometimes noisy as the pair descend locked together from the sky.
* The swift which we see in the UK is called “common” because it is the most numerous across the world. But there are about 100 different species of swift globally. Occasionally, we get visits by the larger alpine swifts as vagrants on the south coast, but you need to go further south to see them regularly.
* For the nine months of the year when they are not with us, common swifts migrate to east and central Africa, particularly the Congo basin, but they come back to the northern hemisphere to breed and raise their young. Ringing and tiny geolocators have now removed some of the mystery about migration patterns for swifts and other species
* The swifts spend their entire time in the air until they are ready to breed in their fourth year (if they have survived that long). Even then, they only come to their nests in holes or boxes or under the eaves to lay their eggs and feed the nestlings. Other than that, they are up in the sky.
* Swifts feed upon micro-spiders and insects such as aphids, hoverflies and plant bugs which they find flying or floating in the sky. A pair of adults might catch 20,000 insects and spiders in day to feed their young, glued together into “feast balls” every hour or so.
* But even swifts need to sleep sometimes. This too happens in the air: at dusk, they will ascend, possibly up to 3000m on warmer nights, and then close off half the brain as they circle until dawn, and then wake up in more or less the same spot in the sky for another day’s hunting.
* Bird’s nest soup is made in eastern Asia from the nests of the “edible-nest swiftlet”. This soup seems to involve a lot of saliva secreted by the birds to bind their nests. So prized is this soup with supposed medicinal benefits, that thousands upon thousand of concrete nesting towers have been built in the region to harvest the nests. They provide an astonishing percentage of Indonesia’s national income: 5% by some estimates! What the swiftlets think about the theft of their nests, for something which Mao regarded as a decadent habit, is sadly unknown.
* Finally, the curious fact that swifts seem to be right-handed. Handedness (or perhaps that should be footedness) has been seen in other animals such as parrots. Given a choice of a row of nesting boxes, swifts will normally pick the right-hand ones. Here in East Sussex, check out the Hastings and Rother Swift Conservation Group via e-voice.org.uk to learn more about these fascinating birds and how you can help.
Andrew Colquhoun