Yes, robins and cardinals have different behaviors when it comes to protecting their offspring. Female cardinals and robins can share a nest, but conflicts can arise, with the female cardinal often becoming more aggressive over time. This sharing of nests typically occurs between American robins and northern cardinals, and it is only the female birds that engage in this behavior. Robins may attack smaller animals around their nests, but they do not typically kill other birds. Cardinals, on the other hand, generally do not attack adult or young birds unless they perceive them as invaders during the mating season. Cardinals do not eat baby robins or other birds.