They take parenting seriously. Very seriously.
I've seen parents dive-bomb hawks, turkey vultures, dogs, and yes, us humans. They are fearless and will do everything they can to distract possible predators from their clutch, even going so far as to land close by and feign injury (not in the extreme, like the killdeer).
There is a nest full of fledglings outside my office window. It's been a hoot watching them go from itty-bitty, featherless creatures to little fluffernutters. Today, one of them decided to become a full-on fledger.
But true to their superb parenting protocol, his parents made sure to feed the nest-abandoner as well. In fact, the father went so far as to taunt the baby bird with an insect, luring him off the bush and up into the air. Thus, he flew for the first time! It was fun to watch.
Sadly these birds are poisoned en masse by farmers. Blackbirds do eat grain, but they are also great insect eaters.