canary in coal mine

LETTER from CHIP NORTHRUP When Canary Croaks, Jump! To the Editor: Miners once took birds down into mines knowing that birds would keel over from methane, lack of oxygen or soot before the miners did. When the canary croaked, out of the mine you go. According to a recent study, birds have been dying off in unprecedented numbers in North America for that last half century. The culprit? Us. The pesticides we use on the bugs that the birds eat…