Tiny Houses for City Birds

City birds have a tough life. Instead of an abundance of foliage to frolic in, cities have glassy skyscrapers for birds to fly into. Instead of nuts, insects, and worms, birds end up eating (and sometimes wearing) discarded human food. City birds also get less sleep than their rural counterparts, and the polluted water they drink makes them sick.

This inhospitable urban environment drives down the numbers of the many, many species of birds native to cities. In the U.K., for example, house sparrows—once plentiful enough to be a nuisance—are now in decline because urbanization has depleted the population of insects they eat.