SUPERNUMERARY REMIGES ON BOTH WINGS OF A RED-TAILED HAWK AND NORTHERN SAW-WHET OWL

摘要

While banding migrating hawks with my Raptor Ecology students on 26 August 2016, we captured a hatch-year Red-tailed Hawk (Buteo jamaicensis) east of Fisher in Polk County. This likely female was captured using a bal chatri trap. During processing, we noticed that she had 11 primary feathers on the right side (Figure 1). After carefully counting the feathers on the right side (several times), we examined the left side and again counted 11 primary feathers (Figure 2). All diurnal raptors normally have ten functional primary feathers on each wing (Newton 1990). An abnormal number, referred to as supernumerary primaries (Stresemann, 1963), has been described in many avian species (Stresemann 1963, Ottosson and Waldenstrom 2002, Cimprich 2008), but only a few reports exist for raptors (Mueller and Berger 1966, Melville 1985, Clark et al. 1988, Nicoletti and Alexander 2006, Driscoll et al. 2015). Although not unknown, documented observations of bilaterally symmetrical supernumerary primaries are extremely rare in raptors (Stresemann 1963, Clark et al. 1988).