A Delicate Balance

Donald looks at the population fluctuations of the migratory barnacle goose

Presently as I write, it is the school October holidays here in the north, so many families will be migrating off somewhere warmer and sunnier. In my schooldays this was the “tattie holidays” i.e. time off to go and gather up the crops of tatties from off the fields.

It is also holiday time for the Greenland Barnacle geese which take flight about now from Greenland, possibly taking a break in Iceland prior to the second leg to Western Scotland [Islay mostly], Northern Ireland and the north coast, Durness/ Eilean Hoan and the crofts of Midtown where I am a ranger.

That is very roughly 1000 miles depending on starting and finishing points. One tracked goose made it in one day, others took many days having to rest on rough seas or stopping off in Iceland for a tea break, quite a  journey by any standards.

They’re somewhat similar to black-and-white Canada geese, though much smaller. Barnacle geese have striking black and white plumage, with white faces and a black neck and chest that contrast sharply against their pale grey bodies. Unlike barnacle geese, Canada geese have black faces and greyer bodies, giving each species a distinctive look despite their similar colours.

Scotland has a population of around 72,000 barnacle geese [in 2020], about six times the number when counts began in the 1950s. The number varies but it is a conservation success despite the recent severe hit of the Highly Pathogenic Avian Influenza which took an estimated 10,000 geese in our sector.

I was out early this morning travelling about to see if I could find the barnacle geese hereabouts to count them, usually on either Eilean Hoan or the Balnakeil farm fields. Happily, I was successful at Balnakeil counting nearly 1000 which is about 1% - a significant number. They are a bit skittish to begin with, probably still on the look out for polar bears and arctic foxes, geese are well known to be good guard dogs!

The Solway Barnacle geese, which hail from Svalbard [a remote Norwegian arctic archipelago], suffered first from avian flu and lost about a third of their population, possibly over 10,000 birds, which is a similar number to those lost in Islay over two winters. Interestingly, White-tailed Sea eagles were reportedly predating on the Barnacle geese and probably were themselves adversely affected by feeding on sick or poorly geese. The eagles are also affecting the distribution of the Barnacle geese who are moving from some historical feeding areas, possibly to gather in larger flocks elsewhere for safety.

Photo by Kato Bergli on Unsplash

There is a working Islay goose management strategy group and a European Goose management working group to assist in calculation the best strategy to protect the Barnacle goose population. The rising number of geese is not universally popular as they consume huge amounts of grazing.

One estimate has a single goose eating 150gms/day, not a lot perhaps, but multiply that by 40,000 across many fields and months, it is significant.

Shooting, by licence, is allowed on Islay but has reduced since the H5N1 outbreak. Shooting is also legal in Iceland, but I believe the numbers have dropped there. Over recent years Barnacle geese have also been breeding on Iceland, there were about 500 nests counted in 2014. Obtaining an accurate count from all the different areas is a difficult and expensive business with spotter planes required in many areas.

Photo by Vladislav Glukhotko on Unsplash

Population monitoring of barnacle geese remains crucial. Conservation measures, such as the EU Birds Directive and Bern Convention, rely on such data to address agriculture and air safety concerns. Management schemes, like the Solway Barnacle Goose Management Scheme, also benefit, balancing population sustainability with agricultural impact.

It is clearly important to have specialist research to provide accurate figures for any population of any species of bird [or animal]. If there are problems with a species, too many or too few, we need to know before we can even attempt to make judgements on what to do.

Humans exert significant influence, and with this comes a strong responsibility to avoid mistakes. The consequences of getting it wrong are, alas, all too evident.

Donald Mitchell is a High Life Highland Countryside Ranger, a keen observer of nature and wildlife, he dedicates his time to documenting and sharing insights about the natural habitats in North West Sutherland. With a particular interest in marine life, he aims to help others gain a deeper understanding and respect for the delicate balance of our ecosystem.