Isle of May 2017 – Seal pregnancies, from delayed implantation to fast births

A grey seal mother giving birth on the Isle of May breeding colony last week

The first two weeks of our field season on the Isle of May have been very busy ones, and we’re now well into the research that we need to get done on the island. In the last week the colony hit peak pupping time, which meant there was lots of amazing births to watch on the island. So, in honour of all the little lives I’ve witnessed come into this world over the last 2 weeks, this blog will be about the wonders of seal pregnancies and births. Births and young pups are fascinating to observe, but please keep in mind that all the observations and photographs we take are done under permit and from hides during research on the breeding colonies as part of scientific projects. Please do not approach or disturb seals during autumn, as they may be pregnant or with pups. Mothers may abandon pups if people come too close, and then the pups will starve to death.

Mother pup interactions are amazing to see, but please be careful where you go to see them and how close you get.

Birth is usually a rapid process in the grey seals here on the Isle of May; we often observe females give birth within ten minutes of visibly starting to push! Many females come to the island prior to giving birth, and either hang around the rocky coast of the island or make forays into the colony in the days before pupping. Female grey seals also show site fidelity (i.e. they go back to the same spot) to the place where they give birth, so we can not only find the same females every year on the Isle of May, but they are found in almost exactly the same places year after year with their current pup. Once a female has given birth to her pup she will usually instantly turn around to begin nosing and sniffing the pup, beginning the bonding process that will keep her by its side for the next 18 days. Grey seal mothers only have 18 days to nurse their pups before they must return to sea. Females don’t eat while they are on the colony, so they loose lots of weight while they are producing fat rich milk for their pups, usually dropping about a third of their mass from when they arrived at the island.

Grey seal mother giving birth in 8 minutes on the Isle of May!

Seal pregnancies are very different to human ones, as they can delay implantation of the growing embryo in the womb, so that it stops developing for a certain time period before it implants and the pregnancy continues normally. This enables grey seals to give birth at the same time every year, despite mating when they leave the colony on day 18 and having pregnancies than only last about 9 months. Many species of mammals, especially carnivores, show delayed implantation, or embryonic diapause, and it is widespread in the pinniped species (seals, sea lions and walrus). However, recent research has found some seal species, like the Weddell seal that lives in Antarctica, may not have delayed implantation. New studies to understand the environmental, nutritional and population pressures driving the evolution of delayed implantation in types of seal will hopefully help us figure out why some species have this physiological adaptation and others do not.

Weddell seal hauled out on D’Hainaut Island, Mikkelsen Harbor, Trinity Island, Antarctica courtesy of Andrew Shiva / Wikipedia / CC BY-SA 4.0

Birth and rearing a young infant is always a testing time for a mammalian mother, and in marine mammals, newborn infants face an additional challenge to their wellbeing. Marine mammals typically have high persistent organic pollutant (POP) burdens due to their top trophic positions in the food chain and the bioaccumulation of the POPs in predators. As these substances are lipophilic (they combine with fat tissues in the body, like blubber) this means that infant marine mammals are at risk from the pollutant burden of their mothers. Some transfer of POPs occurs during pregnancy across the placenta, but once the pup or calf is born, mothers have to produce fat rich milk to feed their offspring with. To do this, mothers typically mobilise the fat reserves in their blubber, and as this tissue has high POP concentrations, these go into the milk she’s producing. By having to drink milk with elevated POP concentrations, newborn marine mammals are continuously ingesting proportions of their mother’s pollutant burden up until they wean, which can have serious negative impacts on their immune system and chance at survival. The PHATS team I’m currently working with is trying to uncover more about the physiology underlying the impact POPs have on fat tissue function and an individual’s ability to generate and utilise blubber properly. By using novel tissue culture techniques in wild breeding colony locations (LINK), we’re hoping to provide new insights and develop new methods to investigate physiological problems caused by such man-made changed to the environments.

Grey seal pup nursing from its mother on the Isle of May

MEANWHILE I’d like to introduce you to some of our study seals! They are all named after the phonetic alphabet, and we watch them from birth, to weaning and beyond to gather data and samples from them. This means that at any one time, we have white coat pups that are still with their mothers, pups that have just weaned and are moulting their white baby fur (or lanugo) and pups that are well into their 1-4 week post-weaning fast, with their spotty adult fur. Below are a few of our study seals, and I’ll post updates about how they are all doing on the blog every week.

Kilo and his mother on the edge of the colony, on the road that leads to Kirkhaven harbour on the Isle of May. He is starting to moult his white baby fur on his flippers and face.

 

Oscar pestering his mother for milk on the colony!

 

Foxtrot weaned from her mother several days ago, and has moulted most of her white pup fluff off

Isle of May 2017 – The last PHATS field season begins

The PHATS team 2017 geared up to head out to the island

The PHATS team is back out on the Isle of May! For the rest of the year, we’ll be out here studying the breeding grey seals and how the physiology of fat tissue in wild animals is affected by persistent organic pollutants (POPs). This year we have 4 team members; Dr Kimberley Bennett and her new PhD student Laura Oller have come from Abertay University, Holly Armstrong has come up from Plymouth University and I’ve come from the Sea Mammal Research Unit at the University of St Andrews.

Driving the lab gear out to the Isle of May

This year the field season has had a rather unconventional start, as for the first week of the breeding season Dr Bennett and I were away in Canada for the 22nd Biennial Marine Mammal Conference (more on this later). So back in mid October we had to do an early provision run to get most of the laboratory gear we need for the 2 month long field season out onto the island. The other field teams working on the seals then arrived while we were still in Canada, and when we finally arrived last week we had to hit the ground running as there were already lots of potential study animals for the PHATS project. Even though we’ve only been on the island for three days, we’ve already found the first five seals for this year’s study cohort, who have duely been named Alpha through to Echo from the phonetic alphabet. We’ll be here until mid december to try and collect all the data we need to finish the PHATS study, as this is the last field season that is planned for the project.

A 1-2 day old grey seal pup on the Isle of May, with a still healing umbilical cord

Outside of the lab we’ve set up on the island, the breeding season is in full swing for the grey seals that have come here to give birth and mate. The number of mother-pup pairs is steadily rising and the large males are already starting to battle for position among the females. There aren’t too many weaned pups around yet, but within a few weeks there will be loads all around the edges of the colony as their 18 days with their mothers comes to an end and the females return to sea, leaving their pups to fend for themselves. Every week I’ll write about a different aspect of the breeding colony and the PHATS project for this blog, with updates on how our study seals are doing and what the field team are getting up to. You can check back here or find me on twitter for updates.

Male grey seals fighting on the Isle of May colony, biting another seal’s hind flippers while they run away appears to be the ultimate insult!
Giving my talk at the marine mammal biennial in Halifax, Canada

MEANWHILE as mentioned above, team leader Dr Bennett and I have been travelling, heading to Halifax, Canada for the 22nd Biennial Marine Mammal Conference to present the findings of the PHATS project so far. It’s always fantastic to get to meet up with fellow marine mammal scientists, hear what discoveries have been made in the last 2 years and show people what you’ve been working on. I also go to take part in a workshop dedicated to a subject that’s become especially important to me, marine mammal endocrinology. It was great to meet all the other people working on the challenging topic of marine mammal hormones, and to hear about the inventive ways people get around working with tricky species like whales out at sea. I’ve had a pretty busy year for conferences in 2017, hopefully we’ll keep finding out new, interesting things from both my PhD on oxytocin and from the PHATS project so we can go to some more next year!

Dr Bennett and I exploring the coast of Canada near Halifax