NC for this, because nobody in physical life has an answer. I don't either and I am normally good at this stuff.
The swallows arrived here in Spring as they have done for decades. I was born here so they are in my blood. They normally have two broods and if it is a wet and cool Summer they hatch further apart so the second brood is younger. All fine, the parents stay with them, building their strength in the air, while the rest of the flock go on ahead. The flock went two weeks ago after a long balmy day chattering on the roof. The 'late' families normally follow on a couple of weeks later when their fledglings are flying stronger.
But this year was unusual. Nature has blips like humans it seems. Magpies and sparrow hawks decimated the first couplings and ate their chicks or snatched the parents. We cannot step in of course. The swallows just get on with it. For some reason a couple lost their first chicks early, had their second brood successfully and then in the blast furnace that was July put nature on hold. After, they attempted to repair their nest and have a third brood in August. We had 30 birds here, all in. Parents and chicks from the original six couples who arrived.
Nature is urgent, demanding and cruel. The 28 flew away leaving the last two fledglings from the third brood behind. That was a week ago. The fledglings are strong flyers and can feed on the wing, but it is getting darker now. It is getting colder and they spend more time on the ledge waiting for parents who will never return this side of the Winter solstice. I saw them an hour ago, in the dark knowing that dark has now crossed over with light.
I know that swallows need to feed themselves. We cannot throw gnats up into the air for them to catch. We cannot put them in a box and Fedex them to Ghana in 36 hours . If we could then sod the cost.
They are going into a torpor and I have no answers. Neither do bird organisations - they rightfully focus on the species and environment not individual birds. I just wanted to share. There seems to be nowhere else on MN for birds or nature (at least that gets much traffic). If there is a bright spark among you, please spark.