All seals are annual seasonal breeders and their oestrus cycles are generally synchronized by when pups are born and weaned (Atkinson, 1997). Peak breeding season is in mid-April to mid-May, but males are in breeding condition longer, from March to June (Burns, 1967). Females come into oestrus right after the end of lactation and their pups have been weaned (Atkinson, 1997). Also, 83% of females get pregnant every year, therefore most mature females breed in successive years (Burns, 1967).

The mating system of bearded seals can be generally described as overlap promiscuity, because seals mate with more than one of the opposite sex whenever they come in contact during the breeding season and there are no long term bonds (Stirling and Thomas, 2003). Because copulation occurs in water (Burns, 1967) and oestrus females in this species are widely spread out at sea, males are unable to monopolize access to females in ways that occur for terrestrial breeders, such as the elephant seal (Van Parijs et al. 2003). Promiscuity has probably been influenced by the fact that males cannot monopolize females because they are solitary and the females have large home ranges with generally unpredictable movements. Also promiscuity occurs because females can take care of the young without the help of males, therefore no bond is necessary between male and female; after mating, the male becomes unnecessary.

Mating Only Territory
Males are thought to have two breeding strategies, territorial and roaming. One strategy is that during the breeding season males form mating territories that are either stationary or slowly moving (Burns, 1967). A study done by Van Parijs et al. (2003) showed that some male seals remained in and patrolled small areas of ice edge or the surrounding water during the mating season, probably indicating that they were patrolling a territory ranging in size from 0.27-12.5 km^2. Male tenure in these areas varied; males frequently left display areas but returned to them after an absence. The other strategy is roaming. The Van Parijs et al. (2003) study also found that other males had movements over larger areas, indicative of roaming. Roaming males showed more overlap of range with territorial males and other roamers, so the researchers concluded that they displayed while roaming across many areas. This study also concluded that although the researchers could not obtain data on age or condition differences between the two groups of males, longer trills from the territorial males could indicate high quality as it does in other mammals and therefore the territorial males could be the more ‘successful’ group. If that were the case then the roaming males would probably be younger animals in poorer condition that were unable to maintain a territory. Also, a study by Van Parijs et al. (2004) showed that territorial males were present in all ice-conditions but roaming males were restricted by fast-ice, therefore, territorial males may gain an advantage over roaming males by being present at the display sites at an early date, when there is more ice cover.

A study by Van Parijs et al. (2000) showed that in general, male territory distribution was not correlated with female distribution, but was correlated with fjord entrances. Males were in higher densities around the entrances to fjords. Van Parijs et al. (2001) explained this behavior by hypothesizing that the male seals were using the natural bottleneck to try to maximize the number of females they could intercept.

The distribution of females during breeding season was strongly correlated with the availability of suitable habitat for birthing their pups, but this distribution was sparse and highly variable throughout the mating season.

Bearded seals also show site fidelity to a particular area (Stirling and Thomas, 2003). But in males that site fidelity varies between the two different mating strategies of males. In a study by Van Parijs et al. (2004) the investigators found that territorial males returned to the same display territories and roaming males returned to the area but not a discreet location over successive years. A study by Gjertz et al. (2000) showed that females come back and give birth in the same general location year after year.

Vocalizations
During the breeding season males ‘sing’ or make a ‘trilling whistle.’ Seals vocalize because it is probably the easiest form of communication in an environment where individuals do not always see each other due to distance, darkness or turbidity (Stirling and Thomas, 2003). The vocalizations of the males have been interpreted to be vocal proclamation or a receptive male advertising his breeding territory (Burns, 1967). Males sing during the breeding season from April to early June with a peak in May (Stirling and Thomas 2003, Van Parijs et al 2001). The trill is repeated over and over again and corresponds with an up and down diving display (Burns, 1967). Male calls can transmit over 30 km and during peak breeding season the rate of calling can be as high 10 calls per minute. Calls can last from 15 seconds to over a minute. Also males can use pitch separation to avoid having their calls be masked by other males. (Stirling and Thomas, 2003). The number of different underwater vocalizations ran from 2 in a Dundas Island study, to 6 in a study around Ramsey Island (Stirling and Thomas, 2003). Also geographic variation has been noted in vocalizations. The development of mating calls has been significantly influenced by their need to mask the calls of other competitors and avoid being masked themselves.
Male bearded seals concentrate their calls to when the conditions are best for females to be close enough to hear them. In a study by Van Parijs et al (2001) Calls had a daily cycle; calls increased by 16:00 hrs. onward and peaked at about 04:00 hrs. This peak corresponds with the period when most females were in the water.

Other behaviors of male seals toward oestrus females include approaching, nudging and chasing. Also researchers have observed males making agonistic threats to neighboring males (Atkinson, 1997)

Implantation in bearded seals is delayed until late July or early August – about 2.5 months after breeding (Burns, 1967). Delayed implantation provides a mechanism so that copulation, fertilization and birth can all happen at the same times of the year, although development inside the mother takes less than a year (Harrison et al. 1968). Atkinson (1997) reported the gestation period in bearded seals to be 11 months, including the period of delayed implantation.

Age of sexual maturity is not fixed in seals but occurs over a range of years, like human maturity (Atkinson, 1997). Females first breed when they are 5 or 6 years old and have one pup per litter. Males are sexually mature at 5 to 7 years, but their sexual maturity is much more variable due in part of their need to gain behavioral experience after they have undergone physiological puberty (Atkinson, 1997).

Image courtesy of Louise Murray, photographed near the Kongsfjorden glacier near Ny Alesund in Spitsbergen, Norway, www.louisemurray.com