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The migration of Siberian passerines is little known, although the number of studies has been increasing recently. However, due to the lack of recoveries of ringed individuals along the East Asian migratory flyway, and the size-dependent limitation on the use of geolocators, studies of the migration routes of small leaf-warblers are scarce. The only promising method is flight range estimation by using biometric parameters to identify migration distances and locate possible stopover sites along the flyway. The aim of this study was to estimate the flight ranges of migrant Radde's warblers Phylloscopus schwarzi, Dusky Warblers P. fuscatus and Pallas's Leaf-warblers P. proregulus at a stopover site next to Lake Baikal, Russia. For the analyses, we used the body mass, fat score and wing-length data of 809 individuals, which were trapped with mist-nets during the autumn migration periods between 2012 and 2017. Our results show that body mass, but not wing length, increased significantly among individuals with increasing fat scores in all study species. The estimated flight ranges of Pallas's Leaf-warbler (724km) and Radde's Warbler (510km) were similar to those of birds studied in a different part of Siberia, and the number of calculated stopovers was also similar between the two areas. In contrast, Dusky Warblers trapped at our study site were estimated to fly shorter distances (217km) and therefore must have stopped more frequently on their way to the wintering grounds.—Bozó, L., Csörgő, T. & Anisimov, Y. (2020). Estimation of flight range of migrant leaf-warblers at Lake Baikal. Ardeola, 67: XX-XX.
Lanzarote island, in the Canary archipelago, is the main stronghold of the Canarian subspecies of the African Houbara Bustard Chlamydotis undulata fuertaventurae. The size of this population has been estimated several times in recent decades, based on extrapolations of bird densities obtained in small sampling areas. Here we present the results of the first complete census of the Houbara population of this island, based on car transects combined with frequent and prolonged scanning stops, and carried out during the mating season, in January-February 2018. Based on a count of 370 birds (161 males, 209 females) we estimate a total population of 440-452 Houbara Bustards on the island. For the first time, a sex-ratio figure was obtained for this species: 1.41 females per male. The annual production of juveniles was recorded for three years and varied between 5.83 and 19.57 juveniles per hundred females. The census method used in this study is proposed as an alternative to the line transects used previously, since it avoids possible methodological flaws that probably overestimate the population. The present method also enables sex ratio and productivity to be determined, and it established the locations of most displaying males. These are important parameters for evaluating the conservation status and reproductive performance of this endangered subspecies of the African Houbara.—Alonso, J.C., Palacín, C. and Abril-Colón, I. (2020). The Lanzarote population of the African Houbara Chlamydotis undulata fuertaventurae: census, sex ratio, productivity, and a proposed new survey method. Ardeola, 67: XX-XX.