The Lundy Bird Observatory is participating in a national Yellow-browed Warbler colour ringing project, aiming to improve our knowledge on the movements and ecology of this fascinating species.
The Yellow-browed Warbler is an ostensibly Asian passerine, breeding in Siberian taiga forests and mostly wintering in SE Asia. The last few decades have seen a substantial rise in the number of Yellow-browed Warblers recorded in western Europe (Fig. 1). This has led to the species being considered an expected autumn migrant, rather than a rare vagrant in Great Britain. There are a diverse range of hypotheses to explain this change in status, not all of which are mutually exclusive.
The project aims to increase the number of Yellow-browed Warblers being ringed in the UK and subsequently increase the recovery rate through the use of colour rings in order to answer some of the following questions:
- To learn more about the trajectory of Yellow-browed Warbler movements within Europe throughout the autumn and into the winter months.
- To investigate whether there is a subsequent southbound movement after birds initially follow a western trajectory, reaching the westernmost limits of Europe e.g., Shetland, Western Isles, Cornwall
- To identify whether YBWs arriving in the UK in autumn are wintering further south in Europe.
- To identify migration stopover duration.
- To identify winter site usage, with increased potential to identify winter site fidelity.
The colour-marking scheme will consist of a colour ring combination using a BTO metal ring on the right tarsus along with three additional colour rings (one above the BTO on right tarsus and two on the left tarsus). Initially seven different colours will be used (Red, Orange, Blue, Green, Yellow, Purple and White) and rotated to every available position, including that above the metal ring. This does not cause duplication with either of the two current existing Yellow-browed Warbler colour ring projects in Europe (both in France).