Swifts catch insects in the air (mainly aphids, cicadas, beetles, flies, mayflies, mosquitoes, ants, butterflies) as well as spiders and form these in their throat with saliva into a hazelnut-sized ball weighing about 1 g (which can consist of 90-800 animals). The food is carried to the nest in the throat pouch. Feeding takes place as the young swift, with beak wide open, appears to swallow the head of the adult bird, while the adult regurgitates the food ball directly into the nestlings throat.
We, on the other hand, have to improvise. One can imagine how strange our well-intentioned help may seem to a young bird and even more so to an adult!
Therefore, we should at least try to stay as close as possible to natural conditions.