But how do they know it's not based on just a few bright stars? Milky way is pretty hard to see with our large human eyes. Insect eyes are good for panoramic views, but much less efficient at low light acuity.
(Be careful, at the CC we accidentally were "those guys"- there were no lights at all except red headlamps, and our car kept lighting up like a Christmas tree)
I once used Google sky on my phone, and I learned what the milky way looks in my light polluted sky. It has become easy since then, but it becomes very difficult on days of full moon.
To show that the beetles were focusing on the Milky Way, the team moved the table into the Johannesburg Planetarium, and found that the beetles could orient equally well under a full starlit sky as when only the Milky Way was present.
If you are somewhere dark, the milky way is very easy to see . . . possibly the most obvious feature in the sky. It is just that light pollution makes it difficult to see from human-inhabited areas: a point which is actually raised in the article as a potential concern for animals that navigate by the night sky.
Yeah, but the bright stars are a part of the Milky Way. So that doesn't address my question.
I really think it does . . . in a planetarium, you can turn on or off whatever you want. In my experience, the milky way switch includes the background glow and not the bright foreground stars which are rendered separately. In these situations, I tend to give the researchers the benefit of the doubt; they generally aren't dumb people.
And I assume these beetles do just fine in light-polluted areas.
I make no such assumption, but even if true, it means that they are using other points of reference (like street lamps) in addition to or instead of the milky way when it is not available. That does not render the conclusion that they use the milky way as one of their references incorrect. Also, we do know that light pollution is a serious problem for some species. If there are bright lights above a beach, hatchling sea turtles will go the wrong way, heading inland instead of out to sea. Apparently, they evolved to head toward the relative brightness of the moon reflecting off the sea.
