Both Common and Grey seals are found around North Ronaldsay. Common seals like to haul out on the sandy beaches but during the breeding season they are found on the rocky shore. They mate in september and the pups are born in June/July. Grey seals prefer to haul out on rocks, especially Seal Skerry, but can also be seen near common seals.

Telling the two apart is easy but takes a little practice. Common seals have a more dog-like face and their nostrils are closer together (narrow septum). North Atlantic Grey seals have a more angular, almost horse-like head and their Nostrils are Apart (wide septum). Grey seals do not breed here. They pup in October, mating over the same time period. They then have a few months 'delayed implantation' until the pups are weaned.