The more you garden, the larger it gets each successive year. You get braver and more diverse. This experimental natural grocery store is not unnoticed by bird, reptiles, and mammals. You'll attract them, because you're providing them with appetizers.
With birds, people try reflective aluminum plates, but honestly a lot of birds like shiny things. I dunno about the effectiveness of it, but sudden movement on strings will probably alarm them. Nets can be made from local plants (see previous postings) and these can cover plants when their fruit or veggies are getting ripe. This helps some, and you have to watch for it, because a flock coming in can harvest a lot quickly.
Likewise, in a post-collapse, a lot of thieving will go on by humans. People will get hungry and they'll decide that those ears of corn or tomatoes are just about right. (Bring in the tomato plants! It's an ongoing GLP joke like moran).
This means that you've got to decide how to handle that post-collapse. For me, community gardening is the way to ultimately handle it, because then it's a theft of everyone's food, and probably will have severe results like no food rations for a week for members stealing from members.
What's more likely is hungry and almost feral children coming in looking for food. You should expect this and some vagrants. That's what happened in the Great Depression. Lots of times people wandered in, even some seniors getting a little senile and forgetting this wasn't their garden. They're hungry and so in those days, when caught they ended up chopping some firewood and maybe got some water and a peanut butter or lard sandwich. It's true, lard sandwiches were common fare.
If it's a bad collapse, very terrible issues could arise from food theft. I'd rather not go there.
If a community gets re-established, vagrant survivors will end up on your doorstep, and the community will have to decide if they'll help some of them. I think they will, and I think YOU will.
The only way you can is based upon the amount of supplies versus what they offer in terms of skills. There's bound to be things like several folks show up, but only one family is accepted. There will be so many hungry mouths to feed, and to even accept one group of four individuals will be very magnanimous indeed. Part of it is the value of that rare skill versus hungry mouths of so many that come with hiring or accepting that person.