Variations in wing morphology among subspecies might reflect different migration distances in Bluethroat

Long-distance migrants have a more pointed and concave wing than short-distance migrants. These pointed and concave wings are thought to minimize the energy-cost of flight. Detailed analyses of wing morphology among populations might therefore offer clues about the migratory behaviour of those populations whose wintering areas are not known. In this work we analysed variations of wing shape of three populations of Bluethroats (Luscinia svecica) from western Europe with different migration distances: L. s. namnetum(breedsmainly inWFrance, winters inWPortugal andMorocco, n = 31), L. s. cyanecula from central Europe (breeds inCEurope,winters in S Europe andNandC Africa, n = 182), L. s. cyanecula from Iberia (breeds in Iberia, but theirwintering areas are still unknown, n = 39). To assess wingmorphology we usedC2 andC3 wingtip shape indices proposed by Lockwood et al. (1998),measuring wing pointedness and convexity, respectively. Males had more pointed and concave wings. As expected, namnetum was found to have a relatively more rounded wing than cyanecula, as well as a more convex wing, agreeing with the fact that namnetummoves shorter distances between its breeding andwintering areas.No significant differences were observed between cyanecula fromC Europe and Iberia. Our results suggest that Bluethroats from Iberia are long-distancemigrants.

Arizaga, F. Campos, D. Alonso, Ornis Fennica 83:162-169. 2006