The arctic tern (Sterna paradisaea) makes an incredible migration each year. These small birds travel distances of more than 50,000 miles, from pole to pole, crossing through temperate and tropical regions along the way. Carsten Egevang used geo-locator tags to track some of these terns, and he shares their story with us in this tour.

Ugandan lepidopterist Perpetra Akite studies at a university in the capital city, far from the farm where she grew up. Since she began studying butterflies as a girl, the landscape of her homeland has changed radically, for butterflies as well as people. It’s change that can be measured in many ways—in the inches of rainfall, acres of forest cleared—or the span of a tiny butterfly’s wings. Ari Daniel Shapiro reports from Kigale.

In this podcast, Ari Daniel Shapiro joins the serious beachcombers along the high-tide line of Sanibel Island, Florida. These “shellers” come in search of beautiful sea shells, sometimes no bigger than a grain of rice, that are the remains of marine snails, bivalves, and other mollusks.

“Sea grapes” may sound like something Poseidon would snack on, and not a killer algae. Yet Caulerpa racemosa var. cylindracea poses a serious threat to marine life. Spread by the bilge water of boats, this fast-growing alga is quick to take root, squeezing out native species. But there is one spot in the Mediterranean where cylindracea hasn’t yet taken over, and biologists like Juan Manuel Ruiz Fernández are trying to discover why.

The red knot is a tiny shorebird that undertakes a mind-boggling migration from the tip of South America all the way to the Arctic Circle. One of the few stops on that marathon journey is the Delaware Bay, an estuary that offers a banquet for migrating birds. Here, for some 20,000 years, red knots have flocked by the thousands to fuel their journey. But humans may be writing a tragic ending to this extraordinary evolutionary success story, unless biologists armed with an unusual tool can win a race against time.

When the cod fishery collapsed in Newfoundland in the early 1990s, the hopes of the local fish harvesters collapsed with it. Hundreds of Newfoundlanders moved away and businesses that depended on the cod fishery closed. But retired schoolteacher Kit Ward of Portugal Cove South wasn't content to watch her community vanish with the cod. She and some friends teamed up to find a solution that was right under their feet, in the reddish rocks of Mistaken Point.

Science contributor Josh Kurz, tells the story of dinoflagellates through “music from the bottom of the food chain.” There are “billions of these microscopic creatures in every bucket of the salty sea,” Kurz reveals. Learn which dinoflagellate has a special glow, and which one is responsible for killing more people every year than sharks.

Pine and stone martens are elusive carnivores that make their homes among the moss-covered, ancient oaks, leaving few clues to their presence. Determining just how changes to the forest are affecting the two species requires some scientific detective work -- and the willingness to gather some rather smelly data.

There’s a chill in the air this week as we travel to a mountain range in Norway in search of muskoxen, Ice Age survivors that once roamed the far north alongside the woolly mammoth. Introduced to Norway from Greenland in the 1940s, muskoxen flourished on these cool, dry slopes until 2006, when the seemingly healthy animals began to die. Ari Daniel Shapiro investigates the muskox mystery.

Atlantic Bluefin can weigh up to 1,000 pounds (454 kgs) and swim up to 45 mph (72 km/ph). Scientist wondered where these tuna were going so turned to electronic tagging to follow them. They were surprised at what they discovered.