<p>Many species can't be easily categorized as nocturnal or diurnal, a new study suggests.</p> <p>The post <a href="https://www.popsci.com/environment/nocturnal-mammals/">Morning lark or night owl? Prevailing ideas of mammal activity are outdated</a> appeared first on <a href="https://www.popsci.com">Popular Science</a>.</p>