Färgade stjärttäckare hos Anser × Branta gåshybrider trots helvita täckare hos båda föräldraarterna

Abstract

I tested the hypothesis that barred or dusky tail-coverts are common in Anser × Branta goose hybrids despite all-white coverts in both parent species. Thirty-two photographically documented Anser × Branta goose hybrids in the author’s archive were assessed. Undertail-coverts were barred or more diffusely dusky in 23 out of the 30 individuals which could be fully evaluated. As to uppertail- coverts, there was some degree of barring or diffuse duskiness in 26 out of the 32 individuals. All-white upper- and undertail-coverts were seen in 1 out of 18 Greylag Goose × Greater Canada Goose hybrids and in 4 out of 5 Snow Goose hybrids; in one Snow Goose × Barnacle Goose hybrid and the only Greylag Goose × Lesser Canada Goose hybrid, barring was restricted to very few uppertail-coverts. In a domestic Swan Goose × Barnacle Goose, under-tail but not upper-tail coverts were coloured. The hypothesis that barred or dusky tail-coverts are common in Anser × Branta goose hybrids despite all-white coverts in both parent species is thus confirmed.