Discovering the Lords of the Sky: The Fascinating Lives of Swifts
France Nichoirs
They zip through our summers at top speed, cleaving the air with their shrill cries. Often confused with swallows, swifts are nonetheless extraordinary birds, true athletes of nature whose lives unfold almost exclusively... in the air!
Discover the secrets of these extraordinary migrants who share our building facades.
🌍 A life suspended between two continents
Swifts are great travelers. After spending the winter in the warmth of Africa, they join us at the beginning of summer to accomplish an essential mission: nesting and raising their young.
But beware, time is short! Swifts only have one brood per year. A clutch generally consists of 2 to 3 eggs, with an average of two young birds taking flight.
🕵️♂️ Family portrait: who are they?
Three species share the territory, each with its own peculiarities:
1. The Common Swift (Apus apus)
It is the smallest, but also the most common of them.
- Size & Weight: 16 cm long, weighing about 50 g (which makes it larger and twice as heavy as a swallow).
- Wingspan: Approximately 40 cm.
- Plumage: Entirely brownish-black, with the exception of a small light bib on the throat, visible only up close.
- Signature: Its cry, a pure and shrill "sriiii" well-known at the end of summer days.
(Image: S. Volpi, Rümlang.)
2. The Alpine Swift (Tachymarptis melba)
Rarer, it is nevertheless very easy to spot.
- Size & Weight: Larger (22 cm) and more robust, it can weigh up to 100 g.
- Wingspan: Impressive, with an average of 55 cm.
- Distinguishing feature: An impeccable white belly, cut by a brown band on the chest.
- Signature: Its cry is a high-pitched trill.
(Image: S. Volpi, Rümlang.)
3. The Pallid Swift (Apus pallidus)
In Switzerland, this discreet cousin is very shy: it is only found in rare colonies in Ticino. Barely larger than the Common Swift (45 cm wingspan), it has slightly lighter plumage. Recognizing it and distinguishing its cry is a matter for specialists!
(Image: G. Boano.)
🚀 Athletes born to fly (and only to fly!)
The swift's morphology is a masterpiece of evolution dedicated to long-duration flight. Its particularly long wings cross in a scythe shape behind its back when it is perched.
Their daily lives are almost incredible:
- Everything is done in the air: It is in mid-flight that they catch their prey (insects and small spiders), drink from the surface of rivers, and collect materials for their nest.
- Nights in the clouds: As early as 1945, researchers proved that common swifts (and alpine swifts outside the breeding season) spend the night in the air! They ascend between 1000 and 3000 meters in altitude and let themselves be carried, conserving their energy. In the morning, they return to their colony without ever getting lost, even after drifting 50 km.
- Zero ground: Their legs are tiny and invisible. Swifts can neither walk nor hop; on the ground, they crawl with difficulty. Taking off from the ground is extremely difficult for them. They therefore never voluntarily land on the ground, but only on vertical surfaces from which they can drop to take flight.
(Image: S. Volpi, Rümlang.)
🥶 Superpower: chicks' survival strategy
Summer weather can sometimes be unpredictable. If adults can escape bad weather over long distances, what do the young do?
From the age of 12 days, juveniles possess a unique ability: they can become torpid and enter a kind of temporary hibernation. Their body temperature drops, their energy consumption plummets, allowing them to remarkably withstand cold and lack of food while awaiting the return of their parents.