Document Type

Honors Thesis

Publication Date

Spring 5-2017

Abstract

Ruffed grouse (Bonasa umbellus) occupy a wide distribution in North America, from Georgia in the south to Alaska in the north, as well as southern and central Canada. Color phases in ruffed grouse range from red to gray with gray phase birds found more frequently at higher latitudes than red birds. Gray and red morphs become exclusive at northern and southern range margins, respectively. This pattern is generally attributed to increased ability of gray morphs to survive northern winters. Although a number of mechanisms have been proposed for these relationships, recent studies on tawny owls have suggested that increased feather barb density and proportion of plumulaceous material in gray morphs may provide an adaptive advantage in northern climates due to increased insulation. Our objective for this study was to evaluate if ruffed grouse exhibit similar relationships between insulating feather characteristics and color phase. We collected dorsal and ventral body feathers from live-caught ruffed grouse and supplemented these with samples collected from harvested birds. We quantified feather length, plumulaceous length, and two barb density measurements for each feather using a dissecting microscope. We used generalized linear models to evaluate differences of feather barb density and proportion of plumulaceous material among color phases. We concluded that the models of color phase, as a predictor of barb density and plumulaceous feather material, were not significant. Our results suggest gray phase and red phase individuals have similar feather barb density and proportion of plumulaceous material, inconsistent with the findings for tawny owls, and that insulating characteristics of feathers likely do not contribute to latitudinal gradients of color phase in ruffed grouse.

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