>>331547David Maitland's "deadlock" is this year's winner of the competition's Behaviour: Other Animals category.
Deadlock (David Maitland/Wildlife Photographer of the Year)
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He told BBC News that the photo was just a glimpse of a struggle between a tree-frog and cat-eyed tree-snake that lasted for hours through the night in the tropical forests of Belize.
"The snake had failed to get its jaws around the whole of the frog's head," he recalled.
"It wouldn't let go, presumably because the frog would have leapt away. But it couldn't swallow it, either."
Neither of the creatures showed any sign of giving up in the three hours that David sat in a cramped position.
"It was a complete stalemate," he added. In the early hours, when the pair had moved beyond the focus of his lens, David decided to call it a night.
When he returned in the following morning, there was no sign of the pair and no clue to which had finally broken the deadlock.