Variable first prebasic molt in Rio Grande and Merriam's wild turkeys

Abstract

Gallinaceous birds typically retain the juvenal ninth (JIX) and tenth (JX) primary wing feathers during the first prebasic molt (Petrides 1945, terminology follows Humphrey and Parkes 1959). However, not all Wild Turkeys ( Meleagris gallopavo ) retain JIX and JX during this molt. Some retain only JX (reviewed by Lewis 1967), and in 21% of 125 Florida Wild Turkeys ( M. g. osceola ), all 10 juvenal primaries were molted (Williams and Austin 1970, 1988). Leopold (1943) suggested that Wild Turkeys were genetically predisposed to retain both JIX and JX, whereas domestic turkeys retained only JX. He further suggested that the frequency of this extended primary molt indicated the degree of cross-breeding between wild and domestic turkeys. Stable frequencies could be maintained if this molting characteristic had neutral selective value. Alternatively, Williams and Austin (1988) hypothesized that the first prebasic molt among wild birds varied in a genetically controlled manner along a north-south gradient related to climate. They predicted that more northerly populations would exhibit progressively higher frequencies of retention of both JIX and JX.