Gentoo penguin chicks have started hatching at Edinburgh Zoo after their parents conducted an annual mating ritual.

The first fluffy chick hatched on Thursday and was soon followed by another three hatchlings, two of which are on the same nest.

The new arrivals are being born after their mothers were wooed with pebbles in a courtship display.

At the beginning of March, keepers at the zoo placed nest rings and pebbles on Penguins Rock to kick off the birds' annual breeding season.

The pebbles are seen as the penguins' version of engagement rings, as males select shiny, smooth stones to present to potential mates.

The first eggs were laid over Easter weekend before a 33 to 35 day incubation period.

Dawn Nicoll, penguin keeper at the zoo, said: "The entire breeding season is an incredibly busy time, but it is all worth it when you see the tiny penguins start to break out of their shells and be cared for by both their parents.

"The rest of the eggs should hatch over the next two to three weeks, as the penguins don't all lay their eggs at the same time.

"We had a very successful breeding season last year, with 16 chicks hatching, so we are hoping for another successful year."

Once the chicks are a little older, they will leave the nest and join a nearby "creche".

Due to the decline in their populations, gentoo penguins are listed as near threatened on the International Union for Conservation of Nature.