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A tale of two Twites

Do British and Scandinavian Twite populations mix during migration?

Jente Ottenburghs
Wageningen University, the Netherlands

LINKED PAPER
Population‐specific migratory strategies of Twite Linaria flavirostris in Western Europe. Dunning, J., Finch, T., Davison, A. & Durrant, K.L. 2019. IBIS. DOI: 10.1111/ibi.12791 VIEW

In winter, you might spot a few Twites (Linaria flavirostris) in a mixed flock of songbirds, looking for food on the brown farmlands. The name of this small bird derives from the distinctive twit-sounds that they often produce. In Europe, you can find several subspecies, such as pipilans on the British Isles and flavirostris in Scandinavia. Mark-recapture studies suggest that these subspecies migrate to different areas outside the breeding season, suggesting that the subspecies pipilans and flavirostris rarely (if ever) mix (Raine et al. 2006). Recently, a group of British ornithologists gathered ringing data from Twites across western Europe to better understand their migration strategies.

Wintering areas
Jamie Dunning and his colleagues analyzed ringing data from 22,622 individual records, covering more than 50 years and 19 different countries. This impressive dataset revealed that English breeding populations winter in the southeastern part of the British Isles, while Irish and Welsh Twites migrate to the coasts in the west, northwest and northeast. Scandinavian birds did not venture across the North Sea but migrated to central Europe. These birds probably move south to avoid the harsh winter conditions on their breeding grounds (Thorup et al. 2017). Not a single Twite ringed in one breeding area was reported in another, indicating that there is little exchange between Britan and continental Europe.

Figure 1 (a) Mean latitude of British (pipilans, dashed line) and continental (flavirostris, solid line) Twite recoveries for each month. NB refers to the non‐breeding season, P indicates passage and Br the breeding season. (b) The seasonal distribution of breeding (green) and non‐breeding (blue) Twites for Britain and Ireland and continental Europe.

Migratory connectivity
The migration patterns arising from this study can also be described in terms of migratory connectivity. This concept refers to ‘the extent to which different individuals from specific breeding populations use similar non-breeding areas’ (Ambrosini et al. 2009, Webster et al 2002). Different British Twite populations used different wintering areas, whereas continental birds from various Scandinavian populations tended to move to similar areas. So, we can conclude that British populations show strong migratory connectivity and continental populations exhibit weak migratory connectivity. This information can be used to guide conservation efforts in deciding which wintering areas need to be conserved. It would be a pity to lose the characteristic twit-sounds from our farmlands (Langston et al. 2006).

References

Ambrosini, R., Møller, A. & Saino, N. (2009). A quantitative measure of migratory connectivity. Journal of Theoretical Biology 257: 203– 211. VIEW

Langston, R.H.W., Smith, T., Brown, A.F., Eaton, M.A. & Gregory, R.D. (2006). The status of breeding Twite Carduelis flavirostris in the UK. Bird Study 53: 55– 63. VIEW

Raine, A.F., Sowter, D.J., Brown, A.F. & Sutherland, W.J. (2006). Migration patterns of two populations of Twite Carduelis flavirostris in Britain. Ringing & Migration 23: 45– 52. VIEW

Thorup, K., Tøttrup, A. P., Willemoes, M., Klaassen, R. H. G., Strandberg, R., Vega, M. L., Dasari, H. P., Araújo, M. B., Wikelski, M., & Rahbek, C. (2017). Resource tracking within and across continents in long-distance bird migrants. Science Advances 3. VIEW

Webster, M.S., Marra, P.P., Haig, S.M., Bensch, S. & Holmes, R.T. (2002). Links between worlds: unraveling migratory connectivity. Trends in Ecology & Evolution 17: 76– 83. VIEW

About the author

Jente Ottenburghs is the BOU’s Journal Publicity Officer and resident science writer. He is a curious evolutionary biologist with a passion for writing. He obtained his PhD from Wageningen University (the Netherlands) where he studied the genetic consequences of hybridization between several goose species. After a postdoc at Uppsala University (Sweden), he returned to Wageningen University for a lecturer position in ecology. Apart from his goose work, Jente manages the Avian Hybrids Project, a website and blog that gathers the scientific literature on hybridization in birds.

Jente’s personal website
View Jente’s profile on ResearchGate
Follow Jente on Twitter @Jente_O

Image credits

Top right: Twite Linaria flavirostris | Imran Shah | CC BY-SA 2.0 Wikimedia Commons

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