Warning: This gallery contains graphic images.

The remains of slaughtered elephants lie amidst the trees near Zakouma National Park in southeastern Chad. Mike Fay, a Wildlife Conservation Society biologist on a National Geographic Society-funded expedition, spotted the animals in early August—two of about a hundred dead elephants seen during a recent aerial survey just outside the park's borders (National Geographic News is part of the National Geographic Society).

Although international ivory trade has been banned since 1989, elephant tusks are hot commodities on the black market. The tusks are actually elongated incisors. Since about a third of their length is inside the skull, the tusks cannot be fully removed while the animal is alive. Poachers therefore shoot into an elephant herd, cut off the trunks of any fallen animals, and hack out the tusks with an axe.

Fay, who was also on assignment for National Geographic magazine, warns that his discovery is evidence of a major poaching problem on the borders of one of the elephants' last central African strongholds. The animals were massacred, his team reports, as they crossed the protected park's borders during the wet season in search of forage.

Get an exclusive look at still and animated images that reveal the elephant massacre Fay and his team witnessed this summer.

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