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 longterm
survival of the species.
It was humans harvesting passenger pigeons for food, however, that drove them to
extinction. In 1855, a single operation was processing 18,000 birds per day! Not even
Audubon himself was concerned that the pace might have an adverse effect on the birds’
population, but the last passenger pigeon died in the Cincinnati Zoo in 1914.