How many niches are in one habitat?
There could be more than one niche in a habitat.
A habitat is a part of an ecosystem: it could be a tree in a grassy meadow, a small pond in the woods, or a big rock on the beach.
On the tree, two or more species of bird may live along with squirrels, bats and different types of insects. Each type of organism lead a different lifestyle though they may live on the same tree. On and around the tree there are many microhabitats, and each species actually occupies only this small part of the extensive habitat.
Niche describes both address and occupation of the organism: thus two species may occupy same habitat but their feeding habit/bahaviour will differ. Organisms use all the resources of a habitat by occupying different niche.
Thus higher the productivity of an ecosystem, more are the resources available, more number of niche are there to support organisms.