Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. True sparrows, the Old World sparrows in the family Passeridae, are small passerine birds. As eight or more species nest in or near buildings, and the House Sparrow and Eurasian Tree Sparrow in particular inhabit cities in large numbers, sparrows may be the most familiar of all wild birds.Generally, sparrows tend to be small, plump brown-grey birds with short tails and stubby, powerful beaks. The differences between sparrow species can be subtle. They are primarily seed-eaters, though they also consume small insects.