National Geographic 2009 international photo competition

Sunset on the African savannah. "The composition presented itself naturally and I snapped it," said photographer Adam Rubin Photograph: Adam Rubin/National Geographic

An adult and a juvenile bearded vulture - a threatened species - quarrel over territory. This picture was taken at Giants Castle in the Drakensberg region of South Africa Photograph: Mitchell Krog/National Geographic

An elephant enthusiastically takes a dust bath in Tarangire national park, Tanzania Photograph: Jonathan Clark/National Geographic

Baobab trees lit up against the dark African sky. Taken in Tarangire national park, Tanzania Photograph: Tom Schwabel/National Geographic

Kwena crocodile farm in South Africa Photograph: Wayne Holloway/National Geographic

Out on our early morning drive in the Ongava reserve near Etosha national park, Namibia, we spotted a shape by the side of the road under a tree. Our guide thought it was a lion but as we approached, the cat lifted its head and it was clearly a leopard," said photographer Sarah Street. "I only had time to get two shots Photograph: Sarah Street/National Geographic

"I have a beautiful Peruvian apple cactus in my yard. Each year it shares six or seven beautiful flowers. Each flower blooms, never more than one in a given day, around 10:30pm and wilts away by 9:30 the next morning. The flower is so beautiful I wanted to photograph it this year. The bumblebee, another resident in my yard, came out to gather pollen at an advantageous time," said photographer Martya Podesta Photograph: Martya Podesta/National Geographic

A gentoo penguin in on Petermann island in Antarctica, taken on a summer's day in November. "This picture is truly where people and nature meet," said photographer Maureen Krill Photograph: Maureen Krill/National Geographic

A one-hour burst of firefly activity in rural Ontario. "The precision of the background star trails is an interesting contrast to the chaotic pattern of the firefly flashes," said photographer Steve Irvine Photograph: Steve Irvine/National Geographic

"The hippos seemed content to nuzzle alongside one another. Most of them appeared to be snoozing contentedly despite the utter lack of privacy or personal space," said photographer Andrew Kaplan Photograph: Andrew Kaplan/National Geographic