Incredible pictures show male penguins searching for the perfect pebble to woo female birds with as mating season begins.

Gentoo penguins at Edinburgh Zoo have started building nests in preparation for choosing their ideal partner.

Staff have set up special nest rings, while the birds have been picking through a mound of smooth stones to find the perfect one.

This year children from Edinburgh Children’s Hospital Charity (ECHC) painted special colourful pebbles for the penguins.

The birds are incredibly popular with children at the hospital who regularly watch them on live webcams at the zoo.

They will now be able to keep up with all the breeding activity at Penguins Rock and watch the penguins pick up their painted pebbles as they use them to build their nests.

Beccy Angus, head of discovery and learning at RZSS, said: “Everyone loves to see the penguins run to pick out the perfect pebbles and present them to their mate.

“This year is so exciting as the children get to watch them build colourful nests with the pebbles they have painted, creating a real, physical connection with the animals they love.”

Roslyn Neely, CEO of ECHC, said: “The pebble-painting session was a real treat for children and young people in hospital.

“One mum told us her daughter loved finding out all about the penguins and the session had really helped to keep her happy and distracted during some tough tests and treatment.”

After choosing a favourite stone, the penguins then choose a mate, and finally choose a nest together.

The first eggs should start to appear in April, with the first chicks hatching in May after a 33 to 35-day incubation period.

The penguin parents share the incubation and parenting duties.

When the chicks reach three to four months of age, they are old enough to leave the nest and join a large crèche with the other penguin chicks.

Whilst in the crèche the young penguins will learn essential skills such as how to swim and feed.