| Now, I thought I'd finish by just briefly describing a few different patterns of migration. Ahhh.... migration varies with the type of bird and the area they come from. For example, one kind of migration is ‘partial' migration. This means that some birds in a particular species will migrate and others won’t. It usually depends on how the weather affects food supplies and very often happens in the tropics. In another migratory pattern, a bird called an Arctic Tern migrates the whole length of the globe, from the north pole to the south. The Arctic Tern travels between twelve and fifteen thousand kilometres each way when it migrates in a complete choose around the world. It's quite amazing! Right and, lastly, I'd like to mention a pattern which isn't nearly as spectacular, but is very interesting. And this is the way many birds migrate across North America. In this pattern the birds fly northwards in the west of the country and then back south again in the east. So, if you imagine it, they’re actually migrating in a circular pattern. like the hands of a clock, not in a straight line, as we might think. |
