Penguin parents practice by incubating egg-shaped stone
A pair of penguins are preparing for parenthood by sitting on an egg-shaped stone at Dudley Zoo.
Keepers have discovered the pair taking it in turns to incubate the rock.
Humboldt penguins pair for life and will lay eggs in the same nesting boxes year-on-year, with both the male and female taking it in turns to incubate eggs for between 40 – 42 days, as well as sharing food-finding duties when the chick is born.