Eggs are laid in the burrows in late spring/early summer. Both the male and the female take turns incubating the egg, with incubation usually taking between 36 and 45 days. Once the egg has hatched the parents take turns leaving the burrow in search of food for the puffling.
Sand eels are a favourite food for puffins. An adult puffin diving beneath the water will hold an average of ten sand eels in its beak at any one time, but there is a record of 62 fish at one time! To hold this number of fish, puffins use the rough spines on the roof of their mouths to avoid dropping their catch.
The puffling spend between 40 and 60 days in the nest before they fledge and swim out to sea. Most puffins leave the island some time in mid July. By early August the puffins will have departed Burhou, with just the colony of storm petrels in the rocks and rabbits that live in the long grass.