Female-biased sex ratios and biometrics of Ruffs Philomachus pugnax migrating through southern Italy in spring

The Ruff Philomachus pugnax frequently uses inland freshwater wetlands as it migrates in large numbers from sub-Saharan wintering areas, across Europe, to northern Eurasian breeding grounds. Until 2005, the Volturno Plain in the northwest of Campania region (southern Italy) was an important spring stopover site for waders migrating along the Mediterranean/Black Sea Flyway. Birds from eastern and western parts of the breeding range may differ in biometrics, but data on populations migrating across Italy are rather scarce. This study describes the sex ratio and biometrics of Ruffs migrating in spring along the southern Tyrrhenian coast. During 1992–2004, a total of 2,633 Ruffs were captured and ringed: 267 males, 2,358 females and eight birds with female-like plumage and intermediate body dimensions, likely so-called faeders. We found a strong female bias amongst the birds caught, and males migrated earlier than females. The numbers caught fluctuated markedly over the years. Comparison of mean wing lengths of adults and second-year birds showed significant differences between both the two ages and sex classes. Males also had significantly larger total head and bill length, nalospi and tarsus length than females. Female Ruffs passing through the Volturno Plain between late March and the first of May in 1992–2004 showed size-related differences in timing of migration, suggesting that shorter-winged birds migrated later than larger birds. The mean wing lengths of birds ringed on the Volturno Plain were shorter than those reported for The Netherlands, Belarus and Ukraine, but longer than those of Ruffs from South Africa, the Yamal Peninsula or the middle section of the Lena River. The data suggest that during the spring migration the southern Tyrrhenian coast is used by different populations.