Once again the Kittiwakes which have been fitted with Geo-locators have returned to breed. Here you can see one of the small devices attached to a Darvic (plastic) right leg ring of the Kittiwake on the left. This device is a small data logger that can be left on the bird over the winter and it records day length and midday sun. This can be used to estimate the location of the bird and does not require much battery power. The devices weigh approx. 2.5g. This is particularly interesting for the non-breeding distribution (or winter migration)
|Kittiwake pair with Geolocator attached to leg ring. Chris Taylor|
The data from the "Skomer" birds was included in a multi-colony tracking study that pulled together data from 19 colonies around the North-east Atlantic over a couple of years - 2008/9 and 2009/10 and included data from a total of 236 loggers.
|Kittiwake - Chris Taylor|
The results showed that "most tracked birds spent the winter in the West Atlantic, between Newfoundland and the Mid-Atlantic Ridge, including in offshore, deep-water areas. Some birds (mainly local breeders) wintered in the North Sea and west of the British Isles. There was a large overlap in winter distributions of birds from different colonies, and colonies closer to each other showed larger overlap. We estimated that 80% of the 4.5 million adult kittiwakes in the Atlantic wintered west of the Mid-Atlantic Ridge, with only birds from Ireland and western Britain staying mainly on the European side."
So it would seem that Skomer birds tend to stay more locally after breeding and not really venturing that far. These types of studies are in their early days. It is vital that this data collection is continued to enable us to further understand and appreciate certain areas of the ocean which need extra care and attention to avoid food shortages/pollution. A relatively small area in the mid-atlandtic has the potential to have large impact on breeding kittiwake population.
Full results published in:
Frederiksen, M., Moe, B., Daunt, F., Phillips, R. A., Barrett, R. T., Bogdanova, M. I., Boulinier, T., Chardine, J. W., Chastel, O., Chivers, L. S., Christensen-Dalsgaard, S., Clément-Chastel, C., Colhoun, K., Freeman, R., Gaston, A. J., González-Solís, J., Goutte, A., Grémillet, D., Guilford, T., Jensen, G. H., Krasnov, Y., Lorentsen, S.-H., Mallory, M. L., Newell, M., Olsen, B., Shaw, D., Steen, H., Strøm, H., Systad, G. H., Thórarinsson, T. L. and Anker-Nilssen, T. (2011), Multicolony tracking reveals the winter distribution of a pelagic seabird on an ocean basin scale. Diversity and Distributions. doi: 10.1111/j.1472-4642.2011.00864.x
Study on Skomer carried out by Oxford University