Appendix. Colophon

The animal on the cover of Java Message Service, Second Edition, is a passenger pigeon (Ectopistes migratorius), an extinct species. In the mid-1800s, passenger pigeons were the most numerous birds in North America. Several flocks, each numbering more than two billion birds, lived in various habitats east of the Rocky Mountains. Flocks migrated en masse in search of food, without regard to season, and a good food source could keep a flock in one place for years at a time. John James Audubon observed that nearly the entire passenger pigeon population once stayed in Kentucky for several years and was seen nowhere else during this time.

Whole flocks roosted together in small areas, and the weight of so many birds—often up to 90 nests in a single tree—resulted in the destruction of forests, as tree limbs and even entire trees toppled. (The accumulated inches of bird dung on the ground didn’t help.) Such roosting habits, combined with high infant mortality and the fact that female passenger pigeons laid a single egg in a flimsy nest, did not bode well for the long-term survival of the species.