Natural Selection

I am going to do a few posts about my recent Shetland trip, which consisted of a week on Foula and just shy of that on Out Skerries. They will hopefully be uplifting and inspiring generally, but it’s not possible to talk about birding Foula this spring without first addressing the impacts of bird flu.

For any readers who don’t know Great Skuas, or Bonxies as they are known in Shetland, are like Herring Gulls but if anything more snarky. They dive bomb you if you get too close to their nests, and whilst you get used to it of sorts in the end it still remains intimidating. Like gulls they are opportunists, whilst the smaller skuas often force other seabirds to regurgitate their food Bonxies are just as likely to drown and eat the unfortunate victim.

Foula is one of the most important places for nesting Great Skuas in the world. It wasn’t always like this, but as the species has prospered it has muscled out the smaller Arctic Skua throughout the island except for a small area around the airstrip. It’s a stronghold within the Scottish stronghold, half the world population nesting in the country.

When you get off a place on the Foula airstrip there’s a defunct ‘Bonxie stick’ holder. ‘WATCH OUT FOR BONXIES’ it says. ‘You NEED our Bonxies sticks!’ It was a fundraiser for the school, they got cash for school trips and you got something to wave in the air above your head to keep the Bonxies at bay. It reflects a grudging tolerance of the islanders’ curmudgeonly summer neighbours as an unusual tourism feature.

Last year on my first visit to Foula everything appeared perfectly normal with the Great Skua population, birds settling down to nest having arrived from sojourns in southern seas. The first signs of a problem came at the end of the 2021 season, with increased mortality of adult birds.

This year though it has accelerated to potentially catastrophic levels. The habits of breeding Bonxies probably don’t help, birds gather together on lochs to bathe and transmission of avian flu is likely facilitated by these social interactions. They aren’t averse to carrion also, and are presumably also vulnerable to getting bird flu this way.

I’m not going to pretend Great Skuas are easy to like, on first impressions they are piratical and thuggish. They’ll probably never strike you though in their marauding dive bombing sorties, and looked at sympathetically it’s basically good parenting. They’ve been one of the few seabird success stories of recent years and now even they are threatened. Fingers crossed they develop immunity quickly or it might be too late.