Climate change has a significant direct effect on terrestrial animals, by being a major driver of the processes of speciation and extinction. The best known example of this is the Carboniferous rainforest collapse, which occurred 305 million years ago. This event decimated amphibian populations and spurred on the evolution of reptiles. In general, climate change affects animals and birdlife in various different ways. Birds lay their eggs earlier than usual in the year, plants bloom earlier and mammals come out of their hibernation state earlier.