These include Vienna (capital of Austria), Bratislava (capital of Slovakia), Budapest (capital of Hungary), Belgrade (capital of Serbia), and numerous other large municipalities. Historically, the Danube was an exceptionally important river to the Greeks and Romans.
At that age, kittens are eating on their own and going to the bathroom on their own, so they can be away from mom for a day while she gets fixed. If mom is feral, when the kittens are 5 weeks old, that is the point when you can get mom spayed and release her right where you trapped her. Kittens can be safely fixed as soon a they hit 2-3 lbs., which is generally between 8-12 weeks.
Usually between 24 hours to look for food and water or avoid predators, then the mother will return and take the baby (while the mother is gone the baby fawn hides in the grass curled up in a ball). It may be well after dark before she returns. 90% of orphan calls to animal control aren't.