Answer:
Some relationships of birds with other species are beneficial i. e. birds and trees. Both contain the relationship of commensalism.
There are some other birds which act like a parasite ad and causes harm to other birds.
Step-by-step explanation:
In commensalism, one organism gets benefit and the other is unharm. Trees provide shelter and food to the birds while birds provide no benefits to the tree. Cuckoo is a parasitic bird which lays egg in the nest of other birds. When these birds hatched, the babies of cuckoo compete with the host's own babies for food.