I didn’t know either until I *saw* it happening.
Since then, I’ve researched them on the internet.
They will not only eat sparrows but the babies of other birds, as well.
They snatch nestlings every chance they get.
I have a huge Black Mulberry tree in my backyard and thanks to the Grackles, we’ve never gotten to eat a single one.
Mulberries are white until one day, they suddenly turn pale pink and then overnight, they will ripen.
Unfortunately, the infernal Grackles also know this and will come under cover of darkness and totally strip the tree of berries.
I’ve gone outside at 5am with a flash light, preparing to get at least *some* of them for us, only to find that the grackles have already come and gone.
Two years ago, some kind of tiny little birds that sort of look like Orioles [without the bright orange] have learned to beat the Grackles at their own game.
I still don’t get the mulberries but at least I have the cold comfort of knowing the Grackles didn’t get them either....;-D
[the odd thing is that those tiny unidentified birds are never here at any other time]
Whatever they are, they’re right smart.
Birds are so cool. We have lots of wading birds, which is a lot of fun since I didn’t grow up with them around. It is still amazing to me to step outside in the morning and see an ibis in the front yard!