The Westray population is of unknown size but this animal is by no means scarce, possibly 500-1000 individuals. Several small colonies exist around the coast with greatest numbers occurring at Sponess and on the Holm of Aikerness. The Bay of Swartmill is a common summer haul-out. Pups are born in June to mid-July and these can swim soon after birth. Many adults are ashore in August when they moult.
A small breeding colony of perhaps 100 adults exists at the Point of Weatherness, some 25 minutes walk from the Rapness Quarry. Pupping takes place in October-November and the young remain ashore for up to a month while they moult the whitish coat they are born with. A large haulout can be seen at low water on the Skerry below Noup Head. Typically this species prefers more isolated and exposed breeding and loafing sites than its’ smaller cousin above.