A presumed hybrid Collared X Pied Flycatcher has been shown to be a 'pure' Pied by genetic analysis, confusing field identification of some black-and-white flycatchers.
A male Ficedula flycatcher at a breeding site in south-east Norway in June 2010 had been fairly confidently identified as a hybrid between Pied and Collared, crossbreeding being a fairly frequent occurrence where the two species come into contact at the edges of their Central European breeding range.
The hybrid assumption was due to the bird having a partial neck collar, as well as relatively large patches of white on the forehead and primary feathers, all of which matched known first-generation hybrids much more closely in feather detail than 'pure-bred' examples of either species.
Workers at the University of Oslo in Norway trapped the bird, collected a blood sample from the male and its seven chicks, and amplified its diagnostic genes with both mitochondrial and genetic markers. All results showed that the bird was genetically a Pied Flycatcher, as indeed were its nestlings. While the authors could not entirely exclude the possibility that the individual male was a backcross with Pied Flycatcher, this likelihood was very remote as most first generation hybrids are unfit and do not survive to breed, and none has ever been identified outside a hybrid zone.
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| The pattern of white on the primaries is clearly more extensive than Pied Flycatcher, but equally less than Collared; in fact the bird's spread wing more closely resembles Atlas Flycatcher! Photo: Glenn-Peter Saetre. |
Pied Flycatcher is part of a closely-related four-species complex that also includes Semi-collared and Atlas Flycatchers, as well as Collared. Semi-collared has a partial white neck collar, as the name implies, but this condition has also been seen in varying states of completeness in Atlas and the Iberian subspecies of Pied Flycatcher, as well as among the Italian population of Collared Flycatcher.
The authors suggest that a partial neck collar may be an ancestral condition that may occasionally resurface as an atavism in individuals of all black-and-white Ficedula forms.
The study also illustrates the shortcomings of identifying aberrant birds merely by their plumage characteristics, and that the identity of putative hybrid individuals of bird species must remain hypothetical without direct observations or knowledge of the parents.
Reference
Bonnet, T, Slagsvold, P K and Saetre, G-P. 2011. Genetic species identification of a Collared Pied Flycatcher. Journal of Ornithology DOI 10.1007/s10336-011-0703-4
