Based on what?\n\nBased on the inconvenient fact that a couple of years ago I spent a lot of time debunking one piece of what you may consider "strong evidence", after another, on Scifraud. Overly gullible members, like you, kept challenging me with evermore pieces of "strong evidence". I finally had more than enough of this issue.\n\nYou are, however, quite welcome to peruse the Scifraud Archive for my posts, under my name, or under rosinbio. (You would first need to subscribe to Scifraud, for free.)\n\nI won't bother to repeat everything I said there. Here are, however, only two points that should give you cause to pause:\n\n1. Check the meaning of the term "navigate", and you will realise that it not even applicable to the "magnetotactic" bacteria. To navigate by using the earth's magnetic field MEANS to move in ANY desired direction in relation to the direction of the lines of force of that field at any point along the way; which those bacteria never do!\n\n2. A lot of the "strong evidence" concerning migratory birds, is based on studying the birds during the migration period, while they are confined inside "orientation ages", "orientation funnels", i.e. when they are NOT migrating at all. It is logically impossible to determine how birds migrate by studying them while they are prevented from being able to even leave the cage, or funnel. One major problem is that when they actually migrate, the directions of their flights are inevitably affected by the direction of the WIND they encounter at each point along their flight-route. And the experimenters cannot know anything about those wind conditions while they and their tested birds, remain in the lab!