Female penguins at Edinburgh Zoo have been wooed with shiny pebbles in an annual courtship display.

Keepers at the zoo placed the nest rings and pebbles on Penguins Rock to kick off the birds' annual breeding season.

The pebbles are the gentoo penguins' version of engagement rings, which the males use to court a potential mate. The black and white birds made a mad dash to pick out their chosen stone to woo a future partner.

Dawn Nicol, penguin keeper at Edinburgh Zoo, said: "The start of penguin breeding season is the busiest time of the year for bird keepers, but it is also the most exciting.

"Every year when we place the pebbles and nest rings into Penguins Rock we love to see the penguins dash off to pick out perfect pebbles and present it to their mate.

"It is also always nice to see how well the pairs look after each other and their eggs, as both parents will share the responsibility of incubating and raising the chicks.

"Once the gentoos have found a mate and filled their nests with the best looking pebbles, the first eggs should start to appear in April, with the first hatchings in May after a 33-35 day incubation period."

The penguins are given a large selection of pebbles to choose from, but the gentoos will often steal the more attractive looking pebbles from their neighbours, which can cause chaos.

Female gentoos then take the shiny new pebbles in the nest rings, which they will then lay their eggs into.

Penguins will often choose to court the same mate for breeding season but, contrary to popular belief, not all penguins mate for life.

Same-sex penguin partnerships are not uncommon and keepers say those couples tend to make great parents.

The zoo's rockhopper penguins are also preparing for breeding season after being moved to another enclosure.

Staff at the zoo are hopeful for rockhopper chicks this year as many of the younger birds have now reached sexual maturity.

Rockhoppers are currently listed as vulnerable by the International Union for Conservation of Nature but due to rapidly declining populations they may be listed as endangered in the near future.

The Edinburgh Zoo "penguin cams" have been moved to the gentoo nesting site to allow fans to keep up with the nesting activity.