You can buy caged feeders that will keep the black birds out.. But there is a down side - birds like cardinals & woodpeckers won't be able to access the feeders either.

Here's a sample-

https://www.amazon.com/Droll-Yankee-Green-Feeder-Domed/dp/B0007LQ2QS/ref=pd_sim_86_1?_encoding=UTF8&pd_rd_i=B0007LQ2QS&pd_rd_r=PNWZ8KMWJC3BND7ZS665&pd_rd_w=6svr3&pd_rd_wg=xMp3d&psc=1&refRID=PNWZ8KMWJC3BND7ZS665

And here's a cheaper sample

https://www.amazon.com/dp/B000LNSWHY

"If so, if there some kind of food for the song birds that may not interest the Europeans?" Not really, these birds eat just about anything...

Well, I take that back - you can put out thistle (nyjer) - tiny black seed that has a shell and requires a special feeder. You DON'T need a caged feeder when feeding thistle because the perches are much shorter so larger birds can't land on them anyways. These feeders are designed for finches.

I have this feeder and it's one of my favs-

https://www.amazon.com/Droll-Yankees-DROCJTHM36Y-CJTHM36Y-36-Inch/dp/B0009U7RGG/ref=sr_1_5?s=lawn-garden&ie=UTF8&qid=1505407923&sr=1-5&keywords=thistle+feeder

Good luck :)

Here's a pic I took a couple months ago showing the finches enjoying my feeder. You can also see my caged feeder off to the right hand side.

I use baffles on all my feeders. They help when weather turns bad. They are supposed to help with squirrels too.