Plumage and Internal Morphology of the "Prairie Grouse", Tympanuchus cupido × phasianellus, of Manitoulin Island, Ontario

Abstract

I made comparisons among populations of Greater Prairie-Chickens, Sharp-tailed Grouse and their hybrids on Manitoulin Island of pinnae length, breast, flank and tail feather patterns, tail graduations, wing chord, and skeletal characteristics. Estimates of the proportion of hybrids from these individual characters ranged from 32% to 60%. Lek behaviour of hybrids was a mixture of the patterns of the parent species. The colour of the booming sacks varied and displayed the range between the parent species. There was a tendency with time for the characters of Prairie Chickens to decline coincident with an increase in Sharptailed Grouse characters. Both Prairie Chickens and Sharp-tailed Grouse are lek species in which an alpha male may consummate most of the the matings. The speed with which morphological change took place in Manitoulin Island is to be expected where a non-random mating system of this kind prevails.