Answer:
Destruction of natural Habitat
Step-by-step explanation:
When the natural habitat of some organisms are destroyed, they find it difficult to adapt to a new habitat and the population could start dying as a result of this. This is believed to be the reason Dinosaurs became extinct (because they couldn't adapt to a cooler habitat).
One of the contemporary challenges destroying natural habitats (hence making some animals endangered) in the world today is climate change.