Update By Parker Levinson, MS Student and 2022 Field Crew Leader:
This has been a year for the record books. Based on how many pups we’ve tagged so far, we predict that it’s going to be one of the highest pup totals in our over 40-year-long data series. In a year with so many females producing pups, we’re seeing a record number of immigrant mothers and have already tagged more than 80 mothers who are new to our study area. We’re also seeing a record number of first-time mothers ranging from ages 4-17.
Weddell seal females typically give birth to their first pups when they are 7 or 8 years old. This is because it takes many years for seals to reach sufficient body size and energetic quality to produce and raise a pup since lactation is very energetically costly. Females reach maximum body mass in their teens and so are still growing when they first start giving birth at younger ages.
Record-tying 4-year-old Weddell mom with her 1st pup photographed by field team member Mairan Smith.
This year amongst the many mothers, the team identified a 4-year-old mom wearing tags 8070C. To us that is really cool as this is the youngest age for a mom that's ever been recorded over the past 40 years, and 8070C is among a handful of seals to produce a pup at such a young age. The last confirmed 4-year-old mom observed was recorded back in 2000. We’re able to trace 8070's lineage back 4 generations. She was born to an 11-year-old mother in 2018, and her mom is still producing pups. In fact, this year, her mom gave birth to her 8th pup at Hutton Cliffs, which is a colony a few miles away from where 8070C gave birth. 8070C’s grandmother was born in 1997 to an immigrant mother, showing that immigrant mothers may contribute to the Erebus Bay population in ways we don’t yet understand.
Aerial image showing where the 4-year-old Weddell mom was born at Hutton Cliffs
and where she was very recently documented with her first pup at Knob Point.
Annotated image by Dr. Jay Rotella.
Aside from tracing this lineage to satisfy my own curiosity, it opens the door to all sorts of research questions about this 4-year-old mom. Did she have an exceptional mother that also started pupping early in life and was able to somehow set her up for success? Was she born in a really good environmental year that helped her reach sufficient mass at an early age? Is she going to produce many pups in her life? Perhaps it’s less about the 4-year-old and more about what’s going on with the environment this year that has allowed so many females to reproduce in this study area. Was it a really good winter with lots of prey availability? Is the next winter going to be very productive so that mothers can regain body mass and pups can have an easier time foraging?
We’ve only ever seen a few 4-year-old mothers in the past 40 years on this project, so we’re curious about what is going on that allowed her to have a pup so early. We’re fortunate to be part of a long-term study that has decades of historic data to help us understand what’s special about this year that resulted in her producing a pup and as we continue the project forward, we’ll be able to follow her in future years to see what she does with the rest of her life.
- Parker Levinson (she/her)
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