Complex sentence: Deforestation of the Amazon rainforest is a continually growing problem which affects all animals and a major threat to migrating birds because it changes or removes sections of ecosystems and habitats.
Split into simpler sentences: Deforestation of the Amazon rainforest is a continually growing problem which affects all animals that reside there. Deforestation is a major threat to birds that migrate because it changes or removes sections of ecosystems and habitats.