HAWAII: NOAA Scientists Report Good News as Monk Seal Moms Reach Major Maternal Milestones
NOAA researchers at our Northwestern Hawaiian Islands field camps discovered two exciting monk seal pupping events in 2019. Both were on Lisianski Island.
When the monk seal field team landed on Lisianski in late May 2019, they discovered 14-year-old mom GV18, in her reproductive prime, with two pups! Could they be twins?
We know that monk seal moms occasionally adopt a second pup, but this usually lasts for only a short period of time because either the mother or the larger pup will drive the adopted pup away. In this case, no other seal mothers were missing a pup and GV18’s two pups were similarly sized, suggesting they were twins. GV18 nursed both pups together and weaned them at a slightly smaller than normal size about a week after being encountered.
A previous review of nearly 5,000 monk seal births over 26 years (1983–2008) revealed only seven sets of twin pups. Thus, monk seal twinning is exceptionally rare, occurring in only 0.1 percent of all births! DNA analysis on those twin pups confirmed they were all fraternal twins, not identical.
This year’s “twins” are not identical, either, as one pup is a girl and the other a boy. When we tag weaned pups, we also collect “snips” of tissue that hold the key to each seal’s genetic makeup. We will have to wait for DNA results on these snips to confirm if the Lisianski pups are indeed twins, but we’re keeping our fingers crossed that we have discovered another rare case of twin monk seal pups
It was with great excitement that the Lisianski field team reported monk seal TG28 gave birth to a pup this year. At 29 years old, TG28 is one of the oldest moms and is now an official member of the very exclusive Super Senior Monk Seal Momma Club! Club members must be a minimum of 29 years old when they have a pup, and to date there are only four club members. The oldest mom is 30 years old and the remaining three members are 29 year old. These celebrated moms are giving birth up through their last years. The oldest female monk seal on record is 32 years old and only two females survived to this age.
Born on Laysan Island in 1990, TG28 is a very special lady, having begun her pupping career as an 8-year-old. For reference, the youngest mom in the Northwestern Hawaiian Islands is 5 years old, though only a handful of 5-year-olds have pupped. TG28 was a homebody most of her life, but in 2015, at age 25, she packed up and moved over to nearby Lisianski.
TG28 is also a member of the equally exclusive Most Productive Mom Club. The record number of pups for a single mother is 18, a record held by just one mom.Two other moms are tied with TG28 at 17 pups each. We are hoping to find TG28 next year with a new pup—tying the records for both oldest mom and mom with the most pups.