Nesting Behaviour. Some species of birds spend a lot of time to build a good nest, well hidden from predators and sheltered from rain. Other bird species do not build a nest at all, laying their eggs on a rocky ledge. Nests can be built in trees, in marshes, on the ground or on cliffs. They may hold from only a single egg to more than a dozen. We'll explore how climate, habitat, the size of a species and the threat from predators has created the nesting habits of various bird species.