this is my suggestion as to how birdstones were used-as hair ornaments. bar-type birdstones are from the glacial kame time period (3000bc to 500bc) they are found from new england to georgia, but are concentrated in ohio, indiana, michigan, new york, and southern ontario. they are made mostly of banded slate and average about 4 inches long. popeyed birdstones are from the same time period and are even more rare than the bar-type. they have protuding knobs representing eyes. bust-type birdstones are the most rare type. they are from the adena (early woodland) to the hopewell (middle woodland) time periods. they do not have the characteristic body or tail and normally consist of the head and neck only. good hunting!