As you can see, the Galapagos mockingbird is none too gentle with its food. This, however, is a survival instinct. The centipede the mockingbird described in the article was eating was poisonous- if the mockingbird wasn't so careful, it could find itself bitten. The Galapagos Mockingbird also takes small crabs along the shoreline and on some islands, has aquired a reputation for pecking open unattended eggs of a wide variety of seabird species, and stealing the eggs of Iguanas and Galapaos Doves. They use their powerful beaks to break through these eggs and to digging for prey in the ground.
Mockingbirds are beneficial to agriculture because they eat so many insects, which eat plants.
If it were not for insect-eaters such as the mockingbird, insects would destroy the world by eating all plants, which give all organisms oxygen. So technically, you can say that we owe our lives to Mockingbirds.