Orientation in Prairie Chickens

Abstract

TH•s paper describes the use of natural features as reference points to territorial boundaries by cock Prairie Chickens (Tympanuchus cupido pinnatus) and the birds' response to experimental creation and movement of mowed edges on booming grounds. Hamerstrom and Hamerstrom (1960) suggest that such natural features as wheel tracks, dead furrows, tussocks, and droppings may serve as reference points to Prairie Chicken territorial boundaries. I found similar features in apparent use for the same purposes on 23 booming grounds in Grant, Linwood, Carson, and Plover Townships, Portage County; and in Sherry and Sigel Townships, Wood County, Wisconsin during 1962, 1963, and 1964. Also cocks relocated territories in response to uncontrolled midseason changes in surface features. Experimental changes in booming ground cover were implemented by mowing to study cock responses in gTeater detail. METHODS Most of this study was conducted during spring booming seasons and largely during the morning display periods. Booming grounds were watched daily between 1 April and 10 June of each booming season in 1962, 1963, and 1964 from blinds on the edges of booming grounds. Individual cocks were identified by colored leg bands (Hamerstrom and Mattson, 1964), or by distinctive variations in plumage, usually the pattern of undertail coverts. Territorial boundaries of cocks were mapped by noting points of contact between adjacent cocks and orienting those points to natural topographic features and/or inconspicuous markers placed on the booming ground in a 25-foot grid. Thus, it was readily apparent when cocks were oftenting to some recognizable feature on the booming ground for territorial boundaries. New grass growth late in the booming season made it possible to create a noticeable edge on two booming grounds by mowing, a.nd then to move the edge periodically by additional mowing. A 2-foot strip was first mowed in the general vicinity of the existing territorial boundaries after a morning display period. If adjacent cocks accepted the line between mowed and untoowed cover as a territorial boundary, another 4-foot strip was mowed beside the existing strip after the display period on that day. Cock responses were again watched and recorded on the /oilowing morning. Additional 4-foot strips were mowed daily until cocks no longer responded or until the study was ended.