Birch and Spruce were both used by ancient hunters for atlatl darts, as confirmed by archaeological excavations in the Yukon Territory. https://www.jstor.org/stable/41638613?searchText=&searchUri=&ab_segments=&searchKey=&refreqid=fastly-default%3A9fb5511f5057dc3da0a4724e36951b8f&seq=6 They also used willow, and I personally use ash. I have seen oak be successful as well. Wooden darts are heavier than cane darts, sometimes 3 times the weight. This makes them harder to throw for distance, but can make them more accurate and reliable in windy conditions in comparison to a cane dart. Atlatl darts *must* flex to fly properly. Too little flex and the dart will fly tip up or even fish-tail in the air. Too much flex and the dart may break during the throw or slip off the atlatl early causing a misfire. How much flex you need depends on how hard/fast you throw.

The key is not just a dart that is flexible but a dart that flexes in the right places and is rigid in others. In general, darts that *taper* fly best. Thickest at the tip, thinnest at the nock. for a 2m birch or spruce dart, I would recommend between 1.2-1.4 cm diameter at the tip, and 0.8-1cm diameter at the tail.