Scientists have long known that birds develop local dialects, but they didn't know that birds' languages can go out of style with the times. According to an article in England's Daily Mail, behavioral ecologist Elizabeth Derryberry tested songs of male whitecrowned sparrows from the 1970's against songs recorded this year. When Derryberry played the modern songs to a group of 10 female and 20 male sparrows, the female birds started courting behavior and the males became territorial. When she played the old-school recordings (which were of the same sound quality), however, the group of birds showed no reaction.
Said Derryberry--a name, by the way, that NEVER goes out of style--the findings are significant proof that "both male and female whitecrowned sparrows respond more strongly to current than to historical songs."
Even to human ears the recordings of the modern songs sound slower and lower in pitch. Slightly more difficult to discern, the sparrows have also ceased using the words 'daddy-o' and 'groovy', and more recently 'bitchin' and even 'cowabunga' have faded into obscurity.