Flight Speed of Ross's Gull, Rhodostethia rosea, and Sabine's Gull, Larus sabini

I report here for the first time measured flight speeds of Ross's and Sabine's gulls, obtained by optical range finder on the northeast Taymyr peninsula, Siberia. For two flocks of Ross's gulls, airspeeds were 12.2 m/s and 14.6 m/s. Mean airspeed for the Sabine's gulls was 13.9 m/s (SD=3.4 m/s. N=6). A comparison of these measured airspeeds with characteristic speeds predicted from aerodynamic theory showed that the Sabine's gulls were flying significantly faster than predicted minimum power speed, but their speed was not significantly different from maximum range speed. Sabine's gulls adjusted the airspeed in relation to head- and tailwinds, which is in agreement with aerodynamic theory.