If you are a big old male Weddell seal, the ladies will love you

Ever wondered what drives male Weddell seal behavior during the mating season? Seals have many needs, such as staying warm in winter and cool in summer, avoiding hungry predators, finding food, and finding mates. These needs can also change with the age of the seal. During the mating season, male Weddell seals try to attract females. However, males must compete against other males for a chance to catch a female’s attention.

Weddell seals live in the Southern Ocean surrounding Antarctica. They come out of the water to rest on the ice for hours or even days at a time. Male Weddell seals fight other male Weddell seals in the water, but they must exit the water on occasion to take a break on the ice. For ringed seals, the locations where males rest on the ice are often dictated by where females are located. Male Weddell seals might follow a similar pattern.

Following food or females?

Some areas of the habitat are rich in food and protected from strong winds and hungry predators. Large groups of female Weddell seals often form where these resources are abundant. To gain the attention of females, males must fight other males. Because males can mate with multiple females per mating season, it is in their best interest to be near large groups of females. Yet, males must still compete against each other to move into the best locations.

As males age, they tend to be larger, stronger, and have a better chance to fight well. Therefore, we might expect to see more older males near large groups of females. However, the oldest males might lose strength and speed in their elder years and might not fight as well. In this case, we would expect the older but not oldest males to have the most females near them.

Age matters

The youngest adult male Weddell seals tend to spend their time in the areas of the habitat with more food resources and fewer adult females. This behavior likely stems from younger males not winning many fights and, therefore, losing chances to mate. Older males are more likely to be found surrounded by many female neighbors. However, current evidence is lacking about the behavior of the oldest males. Some very old males (20 years old or older) are found near large groups of females. However, others are found near smaller groups with (presumably) less competition from other males. Further, the number of female neighbors near a male varies largely across individuals for any age.

Even though age seems to influence where male Weddell seals locate themselves during the mating season, the traits of each individual male seem to be more important. Just like some athletes excel at any age when others make a habit of sitting on the bench, some male Weddell seals are likely better fighters than others at any age. Understanding these unique behaviors of males can help conserve Weddell seals. This information also lends insight into how similar but more threatened species that have been less researched might behave.

Note – this article summarizes my research that was recently published in Marine Mammal Science (see below).

References

• Brusa, J. L., Rotella, J. J., and Garrott, R. A. 2021. Influence of age and individual identity in the use of breeding colony habitat by male Weddell seals in Erebus Bay, Antarctica. Marine Mammal Science DOI: 10.1111/mms.12812
• Krafft, B. A., Kovacs, K. M., Lydersen, C. Distribution of sex and age groups of ringed seals Pusa hispida in the fast-ice breeding habitat of Kongsfjorden, Svalbard. Marine Ecology Progress Series 335:199-206. DOI: 10.3354/meps335199

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Fighting the good fight: survival in male Weddell seals