Hi Trina,
This sounds like a common situation many of us face. It might pay to spend a day (maybe in shifts) sitting, watching, and speaking to any feeders who show up. about how you're trying to help them through TNR. Leafletting or posting signs explaining the process, and why you need to work with them to schedule the feedings is also very helpful. If people understand you don't want the cats to starve, you just need to schedule the feeding so that they'll be hungry for catching, and go to surgery with empty tummies, they're usually happy to help. If they have a trust issue--that you won't return the cats--offer to start with 1 or 2 cats, and then discuss doing more when you bring them back.
With any luck, at least one of those cat feeders will develop a passion for tnr, and become part of a trapping team or network!
If you have a plan to foster/socialize the kittens, ask them if they agree it would be the best plan. Would they want to adopt them once socialized? Give folks some feeling that you're acknowledging their role with the cats, and their attachments. And for the cats that are friendly, carriers are an easier way to go than traps.
You should definitely offer your help to the building manager, so that they don't repeat the mistake of releasing cats abandoned after move-oputs or evictions. If people know there are humane options, they will usually listen and take the humane route.
Scheduled feeding also addresses concerns of attracting other animals. The cats I feed outside leave clean platters that I remove, leaving only fresh water out 24-hours. Until the kittens are 6-8 months, you could work with the feeders on-hand to give kitten "snacks" at appointed times.
If you haven't already taken it, I highly recommend the TNR training (and certification) offered by Community Cats Central and Neighborhood Cats! It's usually offered the first Saturday f each month, and the cost is $10. It is suitable for anyone from total beginners to seasoned trappers. I took it after 35+ years away from TNR activities, and found it gave me confidence in what I had learned/retained from the 1980s, and a few new helpful tips and tricks.
Good luck to you!
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April King
Volunteer and Board Member
Kotor Kitties
+1 206 407 5336
http://www.kotorkitties.org------------------------------