Marina Silva, shown here in Rio de Janeiro on Wednesday, is tied in polls with incumbent President Dilma Rousseff. Silva, the candidate for Brazil's Socialist Party, says if elected next month, she would be "the first social environmentalist president." Silvia Izquierdo/AP hide caption

itoggle caption Silvia Izquierdo/AP

James Cameron talks about how his fascination with the world around him has driven his film career. James Duncan Davidson/TED/Courtesy of TED hide caption

itoggle caption James Duncan Davidson/TED/Courtesy of TED

"The State of the Birds" 2014 report found that red knots (above) and other shorebirds are among the most threatened groups in the U.S. More than half of U.S. shorebird species are on the report's Watch List — species that are currently endangered or at risk. Gerrit Vyn/The Smithsonian Institution hide caption

itoggle caption Gerrit Vyn/The Smithsonian Institution

A Baltimore oriole perches near apple blossoms in Mendota Heights, Minn. Universal Images Group via Getty Images hide caption

itoggle caption Universal Images Group via Getty Images

Opponents of Michigan fish farms say there is no room for them in the lakes because of sport fishing and other recreational activities. sfgamchick/Flickr hide caption

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Off the coast of Southern California, a crowd watches a blue whale rise to the surface earlier this summer. A new study says the population of blue whales off the West Coast is close to historic levels. Nick Ut/AP hide caption

itoggle caption Nick Ut/AP

Chicks in the Perdue hatchery in Salisbury, Md. The company says an increasing number of its chickens are now raised using "no antibiotics, ever." Dan Charles/NPR hide caption

itoggle caption Dan Charles/NPR

A box of chicken eggs painted to look like marbled murrelet eggs. The eggs contain a chemical that induces vomiting. Scientists are trying to teach the endangered bird's predator, a type of jay, to avoid murrelet eggs. Lauren Sommer/KQED hide caption

itoggle caption Lauren Sommer/KQED

Across Washington State, hydroelectric dams are blocking salmon as they migrate to their spawning grounds. Enter the salmon cannon. Ingrid Taylar/Flickr hide caption

itoggle caption Ingrid Taylar/Flickr

Florida Gov. Rick Scott helps release a 30-pound green sea turtle in the Gulf of Mexico in Marathon, Fla., in 2012. The governor is making environmental protection part of his re-election campaign. Andy Newman/AP/Florida Keys News Bureau hide caption

itoggle caption Andy Newman/AP/Florida Keys News Bureau

Patrick Roy's company, Coastal Rental Equipment, used to rent these large pumps to offshore divers who work for oil and natural gas drillers. After the BP oil spill, when the government introduced a moratorium on drilling in the Gulf of Mexico, the Patterson, La., business suffered losses and eventually shut down. Jeff Brady/NPR hide caption

itoggle caption Jeff Brady/NPR

New Yorkers can take city-run classes to learn how to make their homes and businesses less attractive to these guys. Ludovic Bertron/Flickr hide caption

itoggle caption Ludovic Bertron/Flickr

Big brown bats like this one are relatively common in urban areas, sometimes roosting in buildings. Contrary to popular belief, bats rarely carry rabies and are not rodents. They belong to the order Chiroptera, which means "hand-wing." Courtesy of Robert Marquis hide caption

itoggle caption Courtesy of Robert Marquis