On the 6th of January, hundreds of Little Auk (Alle alle) were found in various states of health all over Scotland, many dead. From Orkney to Fife, and even the Hebrides (a friend of mine found one on Bute) these little Birds appeared suddenly on mass, and not on purpose.
Although the UK is part of the bird’s winter range, it was the sudden nature of their arrival that drew attention. Thousands of the birds are thought to have been blown in by storms in the North Atlantic, which the birds were unable to cope with, being only around 20cm long. They are thought to have been on route to the UK, where they spend the Winter due to our milder climate. This species spends most of its life at sea, coming ashore to breeds in the Artic. In spring they congregate far off shore to avoid the icy artic conditions. The onset of winter as well as dwindling food supplies forces the birds to migrate south, seeking winter refuge on the UK coastline, amongst other places. As many of these spring time congregation occur in the North Sea, the bird is found almost entirely on the east coast of the country. Finding them all over the country, as in this occasion, is not common. Something unusual has clearly gone wrong.
Finding seabirds washed up is not unusual, last year over five hundred birds were washed up onto the coast of the UK in one night (I found several Razorbill washed up on a beach in the Clyde Estuary) Mostly Razorbill (Alco torda) and some Guillemots (Uria aalge) which are also members of the Auk family (Alcidea.) Like the Little Auk, they feed far out at sea and can therefore also be affected by storms. The majority of birds were found dead, the ones found alive were severing from exhaustion and malnutrition. Even more shockingly, in France and the Channel Islands, over 11,000 puffins were washed ashore last year.
So what is causing this? If these storms have always occurred, then it is unlikely that the behaviour of congregating out at sea would evolve. The high loss of birds each year to storms, would not make this an evolutionary stable strategy. Therefore, it is only logical that the phenomenon is a relatively new one.
Wind is created when areas of high pressure meet areas of low pressure. This is due to the differences in temperature and moisture between two air masses. Stronger high-pressure systems contain cooler or drier air, the air mass is denser and flows towards areas that are warm or moist, which are in the vicinity of low-pressure areas in advance of their associated cold fronts. The larger the pressure difference between a high-pressure system and a low-pressure system, the stronger the wind. Thus, stronger areas of low pressure are associated with stronger winds. Storms are formed when a centre of low pressure form in a system of high pressure.
As storms get their energy from warm water, the increasing water temperature brought about by global warming, could result in storm formation becoming more common. The abundance in North Atlantic storms has increased rapidly from 9 in 1990 to 11 in 1995 to 15 in 2005. More importantly not only are the frequency of storms increasing, but also intensity. Recent research has shown that we are experiencing more storms with higher wind speeds, which storms last longer and make landfall more frequently than in the past, making them more destructive. Because storm formation is strongly associated with sea surface temperatures, it is reasonable to suggest that the increase in storm abundance and intensity and climate change are linked.
So what does this mean for our sea birds. Unfortunately, it is not good news. As Climate change causes increases in sea surface temperature, these storms are likely to become more frequent. This is bad news for the Little Auk and the rest of its family. As these birds are very well adapted to life at sea, being extremely efficient and agile underwater swimmers, they are not well adapted to flight. Often called the Penguins of the North, has been suggested that the only reason the Auks retain the ability to fly is due to the abundance of terrestrial predators. Something that penguins do not have to deal with in the Antarctic. As they cannot fly very well they are more vulnerable to be affected by storms than other species. Therefore, an increase in this type of storm may result in a decrease in populations of Little Auk, Puffins, Guillemot and all of the Alcidea family.
5,399 total views, 2 views today
Latest posts by Ben Wright (see all)
- Is human intrusion causing Wolves to domesticate themselves? - 8th April 2017
- As the crow flies – How mammal scavengers use birds to locate food - 30th March 2017
- Naturally funny - 30th January 2017