If you are unsure whether your foundling is actually a Common Swift, the section "The Swift -> Identification" will help you.
When young Common Swifts need human help
Always when they are found outside their nesting cavity in a state not yet capable of flight!
This is different from other birds: Many young songbirds that leave their nests very early are in constant contact with their parents and are often mistakenly considered abandoned by concerned but unfortunately misinformed animal lovers due to their contact and begging calls and collected (which usually proves fatal for the bird children).
Young Common Swifts, however, found lying on the ground are lost without human help: Common Swifts never feed their young outside the nesting cavity. Your intervention is therefore justified and necessary! Feathered but not yet flight-capable Common Swifts can be expected from mid-June onwards. Fledged young swifts exist at the earliest from the beginning of July.
The following reasons can lead to a young Common Swift needing help:
Extreme heat
Directly under the roofs, temperatures in summer can reach absurd heights. Young birds often fall when they press towards the entrance holes of their stuffy nesting cavities seeking cooling. These foundlings are usually well-nourished but can still be in very critical condition if they have been exposed to the sun unprotected on the ground for a long time or have been injured in the fall.
Cold spells
In bad weather and scarce food, young Common Swifts beg their parents ever more impetuously for food. Hungry begging directly at the entrance hole or feverish wandering in the breeding cavity can lead to falls. Such foundlings are usually severely emaciated and acute emergencies that can often only be saved by infusions with supplements by a veterinarian.
Absence of parent birds/partner change
Young Common Swifts may attempt a premature jump out of hunger if the parents have an accident and fail to return. If something happens to one of the parent birds, the remaining adult bird does not necessarily succeed in raising all the young successfully. If the young are already very well developed and close to fledging, it may succeed. But otherwise it is more likely that the remaining Common Swift will look for a new partner. This one then throws the brood of its predecessor out of the nest.
Roof work
Roof work is preferably carried out in summer for good reasons. Unfortunately, experience shows that even with knowledge of the existence of a Common Swift breeding colony, consideration is rarely given to breeding birds and helpless nestlings. Many flightless young swifts perish miserably year after year in the debris of roof work, and often not only is the respective brood destroyed, but subsequently every gap is hermetically sealed and thus another breeding colony is destroyed for all time. However, some young swifts have been saved by compassionate construction workers or attentive neighbors. Such foundlings can occur at any age and are generally in good nutritional condition.
Scaffolding on buildings
Shattering dramas and long silent dying play out every year unnoticed behind many a scaffold that is erected for renovation work on a building inhabited by Common Swifts and blocks the way for the approaching adult swifts to their young in the nesting cavities. Here too, vigilant neighbors or residents have been able to prevent the worst when the tragedy was discovered in time, either because of the adult birds permanently circling the building or because half-starved nestlings were found on or under the scaffolding! Scaffolding parts that block the entrance must then be removed immediately (Federal Nature Conservation Act!) so that the Common Swifts can care for their young until they fledge. However, if the nestlings have already been starving for several days, they can usually no longer be saved without human help.
A "crash landing"
Even the maiden flight of an already fledged Common Swift can sometimes unintentionally end on the ground. Problematic fledging conditions (e.g., due to unfavorably located entrance holes, trees in front of the nesting cavity, gusts of wind, etc.) sometimes force even completely healthy, flight-capable young birds to make an emergency landing. Here, only a second start from a raised hand in an open area is needed.
But beware: First, it must be thoroughly clarified whether the Common Swift has been injured! Because often an accident also abruptly ends the first flight of the future master flier: a collision with a power line, a car or a glass pane. Such a "crash pilot" rarely gets off lightly; serious injuries and death are often the result.
It is usually impossible and makes little sense to return fallen young swifts to their nests. Committed maneuvers with fire brigades and ladders would not only be risky but also pointless: Generally, the bird lands down again a little later for the same reasons as the first time, and the risk of injury from falling from a great height has only doubled.
Fallen Common Swifts often lie helpless, hungry, thirsty, perhaps injured on the ground for hours or days before they are discovered. Complications must be expected and a veterinarian specializing in birds should be consulted as soon as possible!