image sourceAlejandro Prieto / Bird Photographer of the Yearimage captionMr Prieto has documented wildlife at the US-border wall and their ecosystems

Mexican photographer Alejandro Prieto's image of a bird at the US-Mexico border wall has won a prestigious photo contest.

Mr Prieto was named the grand prize winner of the Bird Photographer of the Year competition after his image was selected from 22,000 entries.

His winning photograph depicts a roadrunner bird that has stopped in front of the wall.

He says the image highlights the threat to biodiversity that the wall poses.

The US-Mexico border region is a delicate ecosystem with regular animal and bird migrations moving north and south on the American continent.

In this region, a number of species need to cross the border to mate with their genetically different cousins, including the endangered North American jaguar and the black bear, which was re-introduced to Texas in the 1990s.

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"The border wall crosses deserts, mountains and even mangroves. It is not just desert, and is in fact very biodiverse with more than 1,500 animal and plant species threatened by the wall," Mr Prieto said.

"I have watched many different animals reach the wall before turning around and heading back," he added.

Mr Prieto, from Guadalajara, was awarded £5,000 ($6,877) for winning the Bird Photographer of the Year competition. Other categories included Young Bird Photographer of the Year and Urban Birds.

Mr Prieto has been documenting wildlife at the border for over a year. During that time, he said he faced harassment from border control and the constant presence of drug cartels.