<p>Electronic Supplementary Material (1)</p><p>Study sites and research approaches. Our goals at UW differed from those at sites A-D. </p><p>At UW, we studied the acquisition of knowledge about a dangerous person who wore a caveman mask and a straw hat. We continue to study the long-term memory of this information. At sites A-D, we studied short-term (5 month) discrimination among ordinary faces and social learning of these faces by lone, unbanded birds at discrete locations. At all five sites we also investigated the transfer of knowledge about the dangerous face from parents known to be response to the face to recently fledged offspring. Table 1 contrasts each of the five research sites in terms of location, history, crow response, and masks use in tests of discrimination and social learning. Maps of each study site detailing the routes walked and degree of human presence (roading) are presented in the main paper (figure 1: site B; figure 3: UW) and in supplementary figure </p><p>1. Supplementary Table 1. Research approaches differed among the five research sites that were located within 22 km of downtown </p><p>Seattle, WA. Our history of studying and marking birds at each site varied from extensive to non-existent. The response of crows to </p><p> our capture varied, mostly in accordance with persecution at the sites (high in Matlby, low elsewhere). At the UW, we only used two </p><p> extraordinary masks, while at all other sites the same 6 masks were used although a different one of these was the dangerous mask at </p><p> each site.</p><p>Number Mob size Number of </p><p> of crows watching families studied </p><p>Site Location Research captured banding of and methods to Face Masks Used Dangerous Neutral and setting history by people captured investigate </p><p> wearing crows vertical learning</p><p> dangerous</p><p> mask UW University 15 years 4 adults, 3 40 10 in 2007, no </p><p> of observing juveniles radiotagging</p><p>Washington nests and Seattle, WA banding 10-</p><p>15 crows per</p><p> year</p><p>A Magnuson No prior 9 adults, 5 40 1 in 2008, </p><p>Park, research juveniles radiotagged, did </p><p>Seattle, 3.5 not survive to </p><p>Km east of independence</p><p>UW, dense </p><p> suburban B Bellevue, No prior 4 adults, 2 30 1 in 2008, </p><p>WA, 9 km research juveniles radiotagged, did </p><p> east of UW, not survive to </p><p> dense urban independence C Freeway 344 crows 5 adults, 1 15 1 in 2008, two </p><p>Park, banded juvenile offspring </p><p>Seattle, 5.5 from 2001- radiotagged, 1 km 2003 in survived to </p><p> southwest downtown independence</p><p> of UW, Seattle, </p><p> dense urban including </p><p> this site D Maltby,WA 120 crows 8 adults, 7 5 1 in 2008, two </p><p>22 km banded over juveniles offspring </p><p> northeast of 10 years radiotagged, none</p><p>UW, prior to survived to </p><p> suburban to experiments independence</p><p> exurban</p>