9. Many bird species migrate to take advantage of global differences of seasonal temperatures, therefore optimising availability of food sources and breeding habitat. These migrations vary among the different groups. Many landbirds, shorebirds, and waterbirds undertake annual long distance migrations, usually triggered by the length of daylight as well as weather conditions. Migration is highly demanding energetically, particularly as birds need to cross deserts and oceans without refuelling. Landbirds have a flight range of around 2,500 km (1,600 mi) and shorebirds can fly up to 4,000 km (2,500 mi),
10. More than 700 bird species breed in North America, and the variations in their behaviors are fascinating and complex. Different species find mates, build nests, lay eggs, and raise their young in incredibly different ways. This overview is a generalization of the avian nesting cycle. So the main processes are FINDING A PLACE TO BREED, CHOOSING A MATE, NEST BUILDING, COPULATION AND EGG FORMATION, EGG LAYING, INCUBATION, HATCHING, FEEDING THE YOUNG, LEAVING THE NEST
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