Y: It's a problem if their food source doesn't move with them. And it doesn't help that all of the different ways we use land means that the Earth is pretty much a mosaic of different ecosystems rather than larger, contiguous habitats.
And it doesn't help that all ofthedifferentwaysweuselandmeans thatthe Earthis pretty much aMosaic of different ecosystemsrather than larger, contiguoushabitats.