"Prairie Grouse", <em>Tympanuchus cupido</em> × <em>phasianellus</em>, Hybridization on Manitoulin Island, Ontario

Abstract

Greater Prairie Chickens started their range expansion from Wisconsin about 1900. They reached Sault Ste. Marie, Ontario, by 1925 and completed colonization of Manitoulin Island by 1945. In the fall of 1932, an irruption of Northern Sharp-tailed Grouse from the Hudson Bay Lowlands occurred. Residents of Manitoulin distinguished the two species and reported the presence of “square-tails” and “sharp-tails” in the winter of 1932-1933. There is no specimen evidence or verbal reports that Northern Sharp-tailed Grouse reached Michigan during that irruption. Prairie Sharp-tailed Grouse were in the northern peninsula of Michigan by 1930. In 1941, Michigan Department of Natural Resources made a planting of 37 Prairie Sharptailed Grouse on Drummond Island. Thence they spread east and the first lek was found at the west end of Manitoulin Island in 1952. By 1960, these birds had virtually colonized the whole island. Development of a hybrid index from the morphology of specimens of skins and skeletons from Manitoulin indicated that more than 50% of all birds in the 1960s were hybrids. In Michigan, less than 1% of the birds necropsied or checked in hunters’ bags were hybrid. It seems likely that ethological isolation broke down on Manitoulin Island. The booming display of the Prairie Chicken and the tail rattling display of the Sharp-tailed Grouse can be broken down into their component parts. They appear to be homologous to five discrete displays of the Spruce Grouse, grouped in different patterns in each of the two lek species. There was little hybridization between Prairie Sharptailed Grouse and Prairie Chickens that had lived sympatrically for thousands of years. Northern Sharp-tailed Grouse had probably never lived sympatrically with Prairie Chickens and the evolution of the perception of species distinctions may not have evolved to the point where hybridization was restricted to a rare event.