Scientists are not sure how some species of birds are able to navigate with such accuracy when migrating thousands of miles. One theory is that the birds’ brains contain molecules – called magnetite –...

Scientists are not sure how some species of birds are able to navigate with such accuracy when migrating thousands of miles. One theory is that the birds’ brains contain molecules – called magnetite – which contain iron and which somehow enable the bird to detect the Earth’s magnetic fi eld in much the same way that the needle of a compass does. What other possible explanations can you think of?