Try recalling the last time you heard a sparrow tweet in your home. Buildings no longer have those nooks and crannies where little birds could nest. Faced with an acute shortage of housing and food, the homely sparrow is vanishing into the blue.

But it isn’t hard to bring sparrows back into our lives. Raakesh Khatri, director of Nature Foundation, is teaching students and teachers how to create a congenial atmosphere for the little bird by building nests and protecting trees.