David Oehler is curator of ornithology at the Wildlife Conservation Society (WCS)'s Bronx Zoo. Julie Larsen Maher is staff photographer for WCS, the first woman to hold the position since the society's founding in 1895. The authors contributed this article to Live Science's Expert Voices: Op-Ed & Insights.

Penguins are found in the Southern Hemisphere in all shapes and sizes. But today, they are in trouble. They depend on the oceans for food and need coastal areas to nest, rear their young and molt. Sadly, close to two-thirds of the world's 17 penguin species face population pressures from threats like overfishing, oil spills, and man-made changes to the birds' environment.

Fortunately, there are several things people can do to help protect penguins:

Review seafood "watch lists" to make sure the seafood you eat is caught or raised in a sustainable manner. Industrial fishing can result in the significant reduction or collapse of fisheries. Through better management of fisheries, creation of marine reserves, and community participation, fish populations and ecosystems can rebound (and are doing so!). Being a responsible consumer is a critical part of this equation; purchasing fish in a manner that prevents further damage to marine environments will have a positive impact on the heath of penguin colonies dependent on these habitats. Large oil spills are lethal to the environment, including penguins, so make sure your activities do not contribute to the problem. Check fuel and oil lines on your boats, on your car and in your home to make sure they are in good condition. And always recycle the old oil from your car's oil changes. Remember, accidental spills of any pollutants remain in the environment and have been shown to accumulate and concentrate in polar regions. Reduce your carbon footprint to slow climate change, a good thing for penguins. Simple acts like properly filling your car tires can reduce carbon emissions and improve your gas mileage by up to 3 percent. Dynamic climate changes produce rapid alterations in the marine environments and within the food chains that are involved. When we take actions to slow these changes (particularly their impact on polar environments), we help penguins to survive.For more on penguins, see the gallery below.

Diminunitive delights

Consistent with their moniker, "little penguins" are the smallest of the 17 penguin species, at 13 inches (33 centimeters) in height. They are also known as blue penguins due to the indigo sheen of their feathers. They are currently threatened by predators like foxes and dogs, which have been introduced to these penguins' home ranges in Australia and New Zealand. (Credit: © Julie Larsen Maher, WCS.)

Hip hoppers

Rockhoppers sport spiky black and yellow crests of feathers that adorn the tops of their heads. These are among the smallest penguins, at about 22 inches (56 cm) tall. Their numbers have plummeted in the last century as their food supply in South America has become scarce. (Credit: © David Oehler, WCS.)

Consistent cuties

Magellanic penguins return to the same burrows year after year in Argentina, Chile and the Falkland Islands, leaving in the winter. The female lays two eggs, on a nest in the burrow, and both parents take turns incubating them. (Credit: © Julie Larsen Maher, WCS.)

Fluffy fowl

Downy feathers cover newly hatched Magellanic penguin chicks. As a penguin grows and its feathers come in, a juvenile chick will have a combination plumage of both down and adult feathers that resembles a mohawk haircut. (Credit: © Julie Larsen Maher, WCS.)

From down south

Chinstrap penguins are found in Antarctica and the world's other southernmost islands. These birds are distinguished by the feather markings on their heads that look like helmets held in place with a chinstrap, thus the penguins' name. Changing ocean conditions affect their main food source, krill. (Credit: © Julie Larsen Maher, WCS.)

Protected by mom

Recently hatched chinstrap chicks are covered in light-colored down that is not waterproof. Their first month is spent tucked under their parents in nests made of stones. (Credit: © Julie Larsen Maher, WCS.)

Living and loving

Penguins are social animals that live in colonies, like this one of chinstrap penguins. They have complex courtships that include noisy vocalizations. (Credit: © Julie Larsen Maher, WCS.)

Unique specimens

Macaroni penguins are one of six penguin species that have colorful crests of feathers. They are among the penguin species that live farthest south in the sub-Antarctic islands that include South Georgia. (Credit: © David Oehler, WCS.)

Royalty and success

King penguins are the second largest of the penguin species, standing nearly 3 feet (0.9 meters) tall. These king penguins from Chile look to be dressed for success in their formal black and white feathers and distinctive, bright-orange throat feathers. (Credit: © David Oehler, WCS.)

An odd association

The African penguin is also known as the black-footed or jackass penguin. That last alternative name comes from the donkeylike braying sound these birds make. This species is found on the southwestern coast of Africa, from Namibia to South Africa. African penguins grow to 27 inches (69 cm) in height. (Credit: © Julie Larsen Maher, WCS.)

Young and different

African penguin chicks appear darker than the adults and parents in their colonies. It takes several years for the chicks to molt into their adult plumage. (Credit: © Julie Larsen Maher, WCS.)

In addition to documenting field visits, Maher photographs the animals at WCS's five New York-based wildlife parks: the Bronx Zoo, Central Park Zoo, New York Aquarium, Prospect Park Zoo and Queens Zoo. Oehler works with all birds and has a special interest in penguins. He conducts conservation work in South America with rockhopper penguins, macaroni and king penguins. The Wildlife Conservation Society protects wildlife and wild places, and continues to explore how to conserve the areas where penguins are found. Penguins live in three of WCS's wildlife parks in New York: the Bronx Zoo, Central Park Zoo and New York Aquarium. Learn about wildlife on the WCS photo blog, Wild View, including more on penguins in several Wild View penguin posts.

Follow all of the Expert Voices issues and debates — and become part of the discussion — on Facebook, Twitter and Google+. The views expressed are those of the author and do not necessarily reflect the views of the publisher. This version of the article was originally published on Live Science.