Well, the three animals stated above have similar feeding habit,that is, breaking the food into smaller particles especially they love inner part of fruits, cassava and so on. That means that the food particles dropped by these animals eventually rot and form manure for the same plant species. Secondly, with the help of its agents, the feeding habit helps in dispersal of the seeds hence giving room for the new generations to come up and aids equal distribution of the same species over places. Thirdly, the digestion system of the above animals is weaker in a way that the seeds they consumed can not be damaged and therefore germinate where ever they go for pupu,this is most commonly with birds.