Answer from Shekar Dattatri, Conservation India:
Unfortunately, there is no simple answer to your question. If money is not an issue, the best way to protect the sparrows in this particular plot would be to buy the plot and leave the trees intact so that the sparrows can continue living there. Obviously, this would be prohibitively expensive, and require a very wealthy and compassionate philanthropist. Failing that, the sparrows could be trapped and released in another part of town where the species is flourishing. But trapping all the sparrows, or even most of them, is likely to be time consuming. Their fate upon release to a new area may also be uncertain. However, sparrows are very adaptable, and there is a good chance that many will survive and establish themselves in the new area. Perhaps you can get in touch with the folks at https://www.facebook.com/sossaveoursparrows and see if they have any other ideas.