Do skua eat stormies?

Yes.
In the Journal of Ornithology in Oct 2007 there was an article on nocturnal feeding by Great Skua of Leach’s storm petrel on St Kilda. It is well documented that skua feed nocturnally at breeding colonies in the southern hemisphere but not whether their congeners do in the north.
It was important to show skua feeding at night as they also have the potential to forage during the day, possibly taking birds at sea. Using radio-tracking and image intensifiers the group, from British Antarctic Survey, were able to show skua actively feeding on petrels at night. The end result of their study was that, on St Kilda at least, the presence of skua with the petrels was mutually exclusive – the rate of feeding of the skuas may affect the long-term survival of the colony.

So how does this affect Nan Ron? Well, for one, the number of Great Skua present was, to our mind, greater than it had been for the last four years – at one time we had 22 birds in the air (and this wasn’t all of them). So, with increasing numbers of skua there is the possibility for greater predation on stormies.

We collected 15 whole (regurgitated) skua pellets for examination. There were approximately three times this number of degrading pellets that were also looked at. Of those collected and those examined only eight showed absolute signs of containing bits of Stormie. On this rough and crude analysis it appears they may not be – they still feed heavily on crabs. But with this as a nominal baseline we’ll have to do more work next year.