This chapter examines the impact animal activity has on the durability of concrete. It discusses the variety of organisms within Animalia kingdom, the complexity of their life-cycles, plus the relatively small size of the sub-set which cause deterioration of concrete, there is little benefit in understanding the organisms themselves. Thus, the approach taken will be to identify types of animal documented as having caused damage to concrete structures, with a discussion of approaches which may protect structures vulnerable to such attack. The chapter focuses on biodeterioration resulting from concrete being specifically targeted by an animal to satisfy some requirement for survival. It involves the marine animals, since these are the most damaging to concrete, albeit under specific conditions. In most cases the manner in which these organisms attack concrete is comparable, and common solutions exist. The chapter discusses of the potential for damage to concrete from bird droppings.