1. Do they actually belong to someone else? Whose property are they on? For thousands of years people have been keeping flocks that take care of themselves, especially in the good weather months. I know it is hard for some people to believe but it has been going on for thousands of years. Taking something that doesn't belong to you is considered theft in the eyes of the law. Can you get them without trespassing?What are some considerations you guys have?
2. Can you get them all or will you only get the hen and some of the chicks? That would mean leaving the other chicks out there to get by on their own.
3. I have some biosecurity issues but they are not at the top of my concerns. As @Brooks_ said, biosecurity is probably already shot.
4. What are you going to do with them? How do they fit your goals for having chickens? Why do you want them?
5. Probably half of those chicks are boys. What are your plans for the boys?