The December issue features pictures across various categories, from animals in the wild and cultural experiences to scientific advancements and stunning landscapes.

Arndt and researchers at the University of Konstanz in Germany built a see-through ant home that mimicked the insect's natural surroundings to observe how wood ants reproduce.

Through the nest, the photographer watched female colony workers clean eggs, larvae spin cocoons, and hatchlings open cocoons with their mandibles to capture this moment.

Macaws are social birds with a lifespan of 40 to 60 years. They often struggle in captivity, displaying stressed behaviors that make them tough pets. Many are cared for at The Oasis Sanctuary in Benson, Arizona, which is home to around 800 parrots, cockatoos, macaws, and other bird species.

When photographer Hemm Klok visited, the birds' loud noises proved challenging for her work until the sanctuary's director, Janet Trumbule, soothed them with their favorite treat: walnuts.

For the first time in 221 years, brood XIII, with a 17-year cycle, and brood XIX, with a 13-year cycle, emerged simultaneously in the Midwest and southeastern United States, respectively, last May and June. The cicadas only emerge from the ground to reproduce.

Here, Stanmeyer managed to capture the rare moment in Springfield, Illinois.

With only two northern white rhinoceroses left in Ol Pejeta Conservancy in Kenya, scientists from an international project called BioRescue proposed a new solution: using in vitro fertilization to transfer a southern white rhino embryo into a southern white rhino surrogate.

While the pregnancy was a success, the moment was bittersweet — the surrogate mother had died from an unrelated bacterial infection.

Still, the project was an overall win since it meant that the in vitro technique worked on rhinos and could be replicated to potentially save the species from extinction.

In 2024, Gregory — who has been documenting penguins in Antarctica for eight years — witnessed a rarely seen spectacle: a line of young emperor penguins leaping off a tall ice shelf in Atka Iceport, otherwise known as Atka Bay.

Usually, the youngsters' first swim is on low-lying sea ice, where they normally breed.

However, Gregory used a drone to follow the penguins when he saw what was happening. He watched as they successfully jumped off the cliff, an occurrence that scientists claim could become a common sight as the ice melts.

Frio Bat Cave in southern Texas is the spring and summer home of about 10 million Mexican free-tailed bats.

Most nights around sunset, bats fly out in a coordinated stream to feed on moths. "You think maybe it'll finish in 10 minutes," said Tafreshi, but their takeoff "continues for two hours."

Tafreshi used a fish-eye lens and soft flashes to document the moment, creating this 30-second single-exposure image.

About half of the 27 tigers in Similipal Tiger Reserve have black stripes. Still, they've rarely been spotted, even by longtime residents of the village. Still, Yadav was determined to photograph them.

To get them in the frame, he set up camera traps with infrared triggers on 24 trails, three of which ultimately saw regular tiger activity.

After spending 60 days inside the reserve, Yadav finally got this image of a young female tiger, one of just a few photos captured of the black tigers.

To see all 20 of National Geographic's Pictures of the Year, visit NatGeo.com/Photos.