Remove the tree and see what happens to bird population.

I want to be able to identify trees that are important and therefore not be cut. Your answer is not in line with my requirement.

I know your purpose now. I think you can do some observations to see whether birds directly aquire food or other resources from the tree and use the trees as perch site or nest site.

Thanks

Hi Prabhakar, You can monitor the tree in a specific period, then count how many bird use during day and night, how many nests they build, for what purposes they use the tree, breeding, roosting or temporary perching, has the tree supplied food resources such as seed, fruit, insect for birds. Anyway, please be aware that the role of a single tree could be different from a patch of trees, the tree species, their height and size, and their age could have different benefits to birds.

It is a two-way mutualism. Trees provide food and roosting/nesting sites for birds and birds provide a dispersal service. It is impossible to separate these factors in many cases, for example the dispersal of large-fruited propagules in New Zealand by the indigenous pigeon.