Birds' lives are short on the average, largely because the physical dangers are great. Though a parrot is said to have lived so long—on a Pacific island—that it became the only repository of a dead language, few birds in a wild state seem to live more than about fifteen or sixteen years ; but the evidence is still small. Bird-ringing as a general and popular, as well as scientific, occupation does not date back very many years. Pliny talks of marking swallows. A grey heron ringed in Turkey was found in Germany in 1710; but Mr. Nelson tells us that systematic ringing was begun by a Danish schoolmaster in 1899. The practice did not take on important dimensions in the United States till 1920. The Americans consider trapping essential ; and they have been so successful in finding the ideal baits that birds not infrequently develop the trap habit and cannot be 'kept out of their favourite trap even by deportation to considerable distances We may expect notable results from "the biological survey bands," especially those attached to the bigger birds.
* * * *