Monarch butterflies "are not just pretty animals. They are a biological treasure trove." That's the takeaway from a new study on how the tiny insects manage to navigate thousands of miles from the US and Canada to Mexico: Eli Shlizerman of the University of Washington and his team have "cracked the secret" of the compass the insects use, as Science Daily puts it. Azimuth neurons in the eyes track the sun's position, but in order to navigate by the sun, the insects need to know if it's morning (ie, so the sun should be to the east) or afternoon (to the west). And it was known the butterflies do indeed combine these two factors: timekeeping neurons in the antennae operate as a sort of clock. But as researcher Steven Reppert explains in a press release, "how the clock and sun compass talk to each other in a way that leads to oriented flight behavior" remained a mystery.
So the team set out to model the "control mechanisms" involved and then see if their model "could guarantee sustained navigation in the southwest direction." The press release gives a summary: "After estimating the firing rates from neurons in the antennae and eyes, [the team] extrapolated how such neurons might interact with each other in a simplified model. Then, they built equations that would indicate whether a given flight angle was correct or if the butterfly needed to steer left or right in order to face southwest." And, voila: Their model was able to predict the butterflies' behavior. Shlizerman tells the BBC the research may help experts develop a robotic monarch butterfly able to track the migration. (The world's longest-distance flier has been identified.)