Wednesday, 8 April 2015

Olwen's route to Russia

Here on the Woodcock Watch blog we’re always talking about ‘site fidelity’ and ‘faithfulness’ and how woodcock appear to be incredibly loyal to particular wintering and breeding sites. But as with anything, there are always one or two individuals that choose to go against the grain.

Olwen was tagged in Wales in March 2013 and proceeded to migrate to Russia that spring. Olwen returned to spend the winter of 2013/14 in the UK, but instead of heading back to Wales as expected, (s)he spent the whole winter in Yorkshire. In the winter of 2014/15, Olwen switched again and chose a site in Lincolnshire. This is at complete odds to the majority of our other woodcock, who usually return to spend winter at the same site year-on-year.

Olwen has recently left the UK and is heading out on a third spring migration. Whilst Olwen may not be particularly faithful to a single wintering site, (s)he does appear to return to the same breeding site each year (a remote piece of wilderness in northwest Russia). What is most interesting though, is the fact that Olwen also appears to use roughly the same route each time.

The map below shows data from three springs – 2013, 2014 and 2015. Each year, Olwen appears to head from the UK, via the Netherlands and Germany, up through Denmark into Sweden. From Sweden, Olwen passes into Latvia or Estonia by crossing over the Baltic. Here, there is usually a pause in progress, before moving on into Russia.

Click map to enlarge
We have other Russian birds that take a different route. Instead of moving up through Denmark and Sweden, they will make the whole migration overland via Poland, Lithuania and/or Belarus. If you look at now, you can see this in action with our new 2015 birds.

Whilst Ruan and Izzy appear to be following the likes of Olwen and Wensum along the northern ‘Baltic’ route, Monkey IV and Penning are following the southern ‘Continental’ route.

It’s not clear why these birds choose different courses, but as Olwen’s example demonstrates, each individual seems to use roughly the same route each year.

We are lacking large amounts of data on Olwen’s time in Scandinavia; we only have a cluster of 4 points in Denmark in 2013, and 5 in Sweden in 2014. The reason that the data is so scant is probably because Olwen makes this part of the journey quickly with few stops.

From Latvia, however, we have more data. After making the long Baltic Sea crossing, Olwen seems to spend a bit of time recuperating here. In 2014, particularly, Olwen used a site in Latvia’s Talsi muncipality, the area that makes up the Western coast of the gulf of Riga.

Olwen stayed here between 13th March and 9th April. The data we have received recently, shows Olwen was in the exact same place between 23rd and 28th March 2015 (see inset). Within the last week Olwen has pushed further, and is now on the Latvian/Estonian border on the eastern side of the Gulf of Riga.

Below is a photograph of woodland in the Talsi area of Latvia, where Olwen has made an annual pitstop in both 2014 and 2015:

Photo by Anbien from Panoramio
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