Northern mockingbirds are altricial, that means that, when hatched, They're born rather immobile and defenseless and so involve nourishment for a certain length from their mom and dad. The younger have a survival bottleneck for the nestling stage because there are actually increased amounts of nestling predation than egg predation. https://landenvqkey.theblogfairy.com/36199572/facts-about-mockingbird-revealed