Hybrids, intergrades and BBRC

Published on 09 February 2017 in Main articles

From the Rarities Committee’s files

Abstract The spectre of hybridisation (between species) and intergradation (between subspecies) has long haunted BBRC’s work. While some hybrids and intergrades may be easy to identify, others (particularly second- and subsequent generation individuals) may be much more subtle, and difficult to distinguish from normal variation in the parent taxa. Some may be unidentifiable in the field, diagnosable only in the hand or through DNA analysis. This short paper seeks to clarify some of the problems and present a workable policy on hybrids and intergrades.

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Hybrid Black-throated Thrush Turdus atrogularis x Red-throated Thrush T. ruficollis, first-winter male, Banchory, North-east Scotland, March 2013. This bird appears to be a typical Black-throated Thrush but the red hues in the base of the tail are not shown by this species and indicates that this is a hybrid with Red-throated Thrush. Harry Scott