Date: 3/13/17 8:57 pm From: <falcophile...> Subject: [Tweeters] ACCIPITER ID
The perennial Sharpie vs Coop ID dilemma returns.
I highly recommend reading the Josh Hull et al. article cited below. At Golden Gate Raptor Observatory they tested their observers ID skills by releasing 988 accipiters that had just been trapped and banded. 23% of the male Cooper's Hawks were incorrectly called female Sharp-shins. Note that these are high-level (rabid) hawk watchers.
Hull, JM, AM Fish, JJ Keane, SR Mori, BN Sacks & AC Hull 2010 “Estimation of Species Identification Error: Implications for Raptor Migration Counts and Trend Estimation,” J. Wildlife Management . 74(6):1326-1334.
After banding over 500 Cooper's Hawks and 150 Sharp-shins since 2000, I find myself much more comfortable saying "I'm not sure."