Flying across several time zones often causes jet lag, a feeling when the body insists it’s the middle of the night while the clock says it’s lunchtime. Now it turns out this nuisance is not exclusive to humans. A new Science study on Manx shearwaters, seabirds that can fly hundreds of kilometers a day over the North Atlantic, shows they jet-lag themselves during their excursions. And because these birds navigate by the Sun, that jet lag leaves a measurable mark—it skews their compass…