Remember, this is a public park. Thousands of people walk by there all the time, and pay to feed the chickens scratch. Volunteers are their caretakers. These chickens have no biosecurity, never had, never will. They are simply an exhibit and a moneymaker. Seriously, you are reaching for excuses to attack the OP.You don't have to touch the chickens to spread something to them. This is why quarantine areas tend to be as far away as possible from an existing owner's flock-- pathogens may well be airborne, could be carried on the food you bring, these fleas you have treated in your own chickens (fleas, really, yikes!) Can and will jump, things get carried in on shoes. Simply refraining from touching them, does nothing in a biosecurity sense.