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.
Feral kittens are usually first noticed when they start romping away from the nest at 4 weeks old. The best time to catch them for taming is 5 - 8 weeks old when they are no longer dependent on their mother's milk. Though cute, a frightened feral kitten will defend itself vigourously if cornered so a trap or stout gloves (e.g. welder's gauntlets from DIY shops) are essential.