Executive Summary Stakeholders in management of mountain lions in the Flagstaff Uplands of northern Arizona have expressed increasing concern about both potential impacts of humans on lions and potential risks posed by lions to humans. A series of human-mountain lion encounters during 2000-2001 on Mt. Elden, immediately adjacent to Flagstaff, and similar incidents during 2004 near Tucson brought increased attention to management of human safety in mountain lion range. These human-centered concerns, together with long-standing questions about how the human infrastructure centered on Flagstaff might be affecting lion movements led us to initiate a mountain lion study in 2003 which we plan to continue through 2009. Our study focuses on movements and other behaviors of mountain lions, with the goal of providing information that can be used to increase human safety, decrease human impacts, and, overall, provide insight into the ecology of lions in this region. To serve this goal, we have focused on collecting data that will be the basis of explanatory models that can provide spatially-explicit predictions of mountain lion activity, specify the effects of human facilities, such as highways and urban areas, and provide insight into when, where, and how often different kinds of lions kill different kinds of prey. During 2003-2006, we captured six female and five male mountain lions in the Flagstaff Uplands, 10 of which we fitted with collars that collected up to six high-precision GPS fixes per day, transmitted daily to our offices via Argos satellites. This timely delivery of data allowed us to visit kill sites and other foci of localized activity to collect detailed information on lion behavior. By June 2006 we had obtained 9357 GPS locations and visited 394 sites, at which we documented 218 kills, 165 of which were by five females and 53 by five males. These data were the basis for preliminary analyses presented in this report. All lions during all seasons exhibited a strong selection for rough terrain and forest or woodland cover. Females differed from males by selecting more strongly for intermediate, rather than extreme, levels of terrain roughness, by selecting more strongly for chaparral vegetation and related rocky areas during winter, and by not selecting as strongly for areas near water sources. Overall, lions collared during this study strongly avoided flat open areas in private ownership. Male but not female lions exhibited pronounced selection for National Park Service jurisdictions. Both males and females year-round avoided residential areas and a zone outward to about 1-3 km and, when within this zone, moved more slowly and with less change in direction compared to when farther away. Collared lions have so far rarely crossed paved highways of any description - orders of magnitude less often than expected by chance. We observed only 3 crossings of an interstate highway, all on I17 and none on I40. Elk comprised the majority (52%) of kills by lions in our study, followed by mule deer (46%), and small mammals (15%). Adults comprised most of the mule deer kills (68%) and mesocarnivores, primarily coyotes (n = 21), comprised 73% of smaller prey. Calf and short-yearling elk comprised the largest single category of kills (29%). In addition to kills, we documented seven instances of scavenging, involving four different lions. Females differed from males by killing more mule deer and virtually all of the mesocarnivores, and by killing fewer elk of all ages. Intervals between kills averaged between 144 hrs (young females) to 221 hours (adult females), whereas average time spent on a kill ranged from 19 hrs (adult males) to 40 hrs (young males). Carcass mass had a strong effect on likelihood that a lion would bury or relocate a kill, the percentage of edibles consumed, and overall time spent feeding. Time spent feeding and likelihoods of carcass burial and relocation all peaked at intermediate carcass masses, suggesting an optimal mass in the range of 50-150 kg, likely dictated as much by handling efficiencies and competition from other scavengers as by a lion's shear ability to kill prey. Adult male lions exhibited a life strategy distinctly different from all other sex-age classes that entailed moving more rapidly over larger areas, and spending less time on kills in which they invested less energy handling, but from which they consumed tissue at a higher sustained rate.