| 2009 IUCN Red List Category (as evaluated by BirdLife International - the official Red List Authority for birds for IUCN): Least Concern Justification This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is extremely large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern. Family/Sub-family Sylviidae Species name author (Gmelin, 1789) Taxonomic source(s) Cramp and Simmons (1977-1994), Dowsett and Forbes-Watson (1993), Sibley and Monroe (1990, 1993) Taxonomic note Sylvia crassirostris has been split into S. crassirostris and S. hortensis on the basis of differences in coloration, biometrics and mt-DNA (Shirihai et al. 2001), to which Baerlein et al. (2006), although they did not accept the split, added moult pattern. However, the colour differences are minor, the biometric differences (as independently presented in Cramp 1992) show much overlap, the vocal differences are not particularly strong (and with no indication whether they converge where the ranges converge), the moult pattern is difficult to evaluate taxonomically, and the molecular evidence remains unpublished after at least six years. Therefore this split is not accepted until better evidence is provided.
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