As the puffin catches more fish, they cannot all be held close to the proximal end of the mandible, however the roof of the mouth is furnished with a double row of backward projecting spines that help to keep the fish in position. Reproduction It takes five years for puffins to reach sexual maturity. When Fratercula coniculata has reached this stage, they return to land in the summer to breed. Horned Puffins are cavity nesters. They tend to build their nests in burrows, or in the crevices in cliffs.
Puffins tend to have a monogamous mating system.
The pair will usually mate for life unless, after a few copulations, no eggs are produced. Horned Puffins lay only one egg a year. Incubation tends to last 42-47 days. Both parents also incubate the egg by placing it under one wing and leaning their body against it. When the young puffin hatches, the parents take turns protecting and feeding it.