Seabird colonies are thought to be in rapid decline. But knowing just how severe the loss is can be a challenge, so some scientists are turning to bird poop for the answer.
Fish need to cross roads too. But the tunnels built to channel rivers under roads and railways can block their migrations.
Why did Earth's climate rapidly cool 12,800 years ago? Evidence is mounting that a comet or asteroid collision is to blame, with new support coming from the bottom of a South Carolina lake.