Before giving birth the female excavates a birth lair in a snowdrift over a breathing hole, and it is here that her pup is born in late March or April. Significant snow cover is required for lair construction. Protecting against cold air temperature and high wind chill, the lair provides a warm microclimate for the growing pup, reducing its energy requirements to keep warm (Belikov and Boltunov 1998). It also offers some protection from foxes and polar bears (Lydersen 1998, Rosing-Asvid 2010). Pups born outside lairs have a very low chance of survival. Females have a complex of lairs (4 to 6) and can move young pups between lairs if one lair is attacked; older pups will move by themselves (Kovacs et al. 2008). However in some areas, like the Baltic Sea (Härkönen et al.1998), ringed seal pups are born on bare ice. Like many ice-breeding seals, the newborn pup has a white natal coat that is shed in 4 to 6 weeks and replaced by a coat with juvenile coloration.
Model of a ringed seal pupping lair on the sea ice; Natural History Museum, Copenhagen, Denmark. Photo: A. Rosing-Asvid
The pup is about 60 cm long and weighs around 4.5kg at birth. It nurses for 5 to 7 weeks, and is weaned at approximately 88 cm in length and a weight of 22 kg (Rosing-Asvid 2010). It is quite active during the nursing period and may spend a large proportion of its time making short feeding dives under the ice (Lydersen 1998). Females lose mass rapidly during lactation (over half a kilo per day), despite the fact that they forage under the ice during this period (e.g., Reeves 1998).
Breeding takes place in April to May, probably beneath the ice. Rutting males exude a smelly oily substance from glands in their face, which gives them a dark face mask. They use it to mark their breathing holes. Breeding males often have bite wounds, and it is therefore believed that they exhibit territorial behaviour and fight with other males (Lydersen 1998, Reeves 1998). This is supported by the spatial distribution of various age- and sex groups of ringed seals in fast-ice breeding habitat, with competitive exclusion of sub-adults and some adult males outside the prime breeding areas, where the male:female sex ratio of 1:2.4 suggests a slightly polygynous mating system (Krafft et al. 2007).
Ringed seals can begin to moult as early as late April, with the number of moulters increasing in May and peaking in June. The seals spend a lot of time (up to 60%) hauled out on ice basking in the sun both just before and during moulting, a behavior attributed to the need to maintain an elevated skin temperature (Kelly et al. 2010ab). Feeding activity is at a minimum during the spring moult and ringed seals lose a lot of weight and are therefore thin in the summer (Ryg et al. 1990, Rosing-Asvid 2010). Consequently they sink more easily when hunted in the early summer. In August-September, they begin to put on weight again and by December they have returned at their maximum weight.
More information about Behaviour can also be found in Life History and Ecology