Take them up there they will work with you
Try the TNR program. It's great. They spay/neuter, clip the ear and return them.
Call them, they're really nice and helpful in these matters. They will advise you as to what your options are. Maybe ask for a "group" discount. Btw, that's really nice of you to take good care of those cats!
you can also reach out to Barcs in Baltimore. They have special days where they charge a very small fee for spading.
Anne Arundel County animal control has a complete list of organizations that offer free or low cost spay\ neuter.
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