So, the slobbity little birds that use my feeder tend to strew the seed; they did not, after all, evolve to eat from feeders, so I can't blame them. In any case, they had "planted" quite a forest of sunflowers under the feeder.
I was just going to leave the sunflowers; they weren't interfering with anything. But then I got home from work one day and saw this:
That's one of the neighborhood cats. I call it Scruffian.
At twilight, and with the feeder empty, I wasn't much concerned ... despite its proximity to the feeder.
However, Scruffian was still there (or there again) in the morning. After chasing it away, I refilled the feeder ... then went back out and pulled up most of the sunflowers.
(Not the best photo. The camera didn't know what to focus on.)
I pulled out the volunteer sunflowers because the birds were nervous. They didn't like not being able to see under the plants. And I didn't want to go out one morning and find bits of an eaten bird.
They may just be city birds, but they are now MY city birds, and nobody's cat is welcome to try and eat them.
Scruffian is still coming back, and I'll have to find some way to keep it from camping under the feeder, because I can't always be around.
Recent observations revealed that Scruffian is one of a matched pair of cats which nominally belong to someone across the street from us. This takes certain interventions off the table. There are one or two options I can try to discourage the cats from hanging around the feeder, but ultimately it will come down to vigilance: feeding only when I'll be around for half an hour or so, so I can keep an eye on the yard and chase the cat(s) away if necessary.
And none of that would be necessary if people would keep their pets inside.