Session 5: WFA – Felid Population Monitoring Conceptual Framework for Estimating Mountain Lion Density with Motion- activated Cameras Jesse Lewis, Department of Fish, Wildlife, and Conservation Biology, Colorado State University, Fort Collins, CO 80523, jslewis@rams.colostate.edu (presenter) Kevin Crooks, Department of Fish, Wildlife, and Conservation Biology, Colorado State University, Fort Collins, CO 80523, kcrooks@warnercnr.colostate.edu Larissa Bailey, Department of Fish, Wildlife, and Conservation Biology, Colorado State University, Fort Collins, CO 80523, larissa.bailey@colostate.edu Linda Sweanor, President of Wild Felid Association, Montrose, CO, lsweanor@gmail.com Brady Dunne, Colorado Division of Wildlife, Montrose, CO, abdunne88@hotmail.com Sue VandeWoude, Department of Microbiology, Immuniology, and Pathology, Colorado State University, Fort Collins, CO 80523, Sue.Vandewoude@colostate.edu Ken Logan, Colorado Division of Wildlife, Montrose, CO, ken.logan@state.co.us Abstract : Reliable population estimates of wildlife are critical for management and conservation. It is particularly challenging to obtain population estimates of mountain lions due to their secretive nature, inherently low population densities, and wide-ranging movements. Estimates of population characteristics for mountain lions would be especially useful to wildlife agencies in western states that manage hunting seasons on these populations. The goal of this ongoing pilot study was to evaluate whether reasonable estimates of mountain lion density could be obtained with motion-activated cameras to inform future efforts to estimate mountain lion densities across an appropriately broader spatial scale. Our study site consisted of 40 motion- activated camera sites spaces approximately 2-km apart within two 80 km 2 grids, constructed on the Uncompahgre Plateau, CO, for the primary purposes of estimating occupancy of sympatric mountain lions and bobcats and to estimate bobcat density. Using mark-resight techniques in program MARK, we estimated the super population size of mountain lions using our camera grids and then used telemetry data to determine the amount of time that animals spent on camera grids to estimate population density for our grid areas. This mountain lion population has been the subject of an intensive radio-collaring and demographic study since 2004. Over a 3.5 month period during summer and fall 2009, we obtained 80 photographs of lions (51 marked, 29 unmarked) and detected 9 marked mountain lions using our sampling grids. The amount of time spent on grids was calculated for 8 mountain lions wearing functioning telemetry collars and ranged between 8 – 64%. We discuss how these results could inform camera grid designs scaled specifically to mountain lions to obtain better population estimates. These considerations might also be useful for designing camera and mark-resight methods for other species of large solitary- living felids. 131
Session 5: WFA – Felid Population Monitoring KEYWORDS : cougar, density, mark-resight, motion-activated cameras, mountain lion, population estimation, Puma concolor INTRODUCTION Estimates of population size, density, and trend for mountain lions ( Puma concolor ) have been obtained through intensive telemetry studies (Logan and Sweanor 2001), track surveys (Smallwood and Fitzhugh 1995), and identifying unique individuals based on natural markings using motion-activated cameras (Kelly et al. 2008; Negroes et al. 2010). If a proportion of a mountain lion population consists of marked individuals (e.g., through telemetry collars and/or eartags), motion-activated cameras can also be used to estimate population size using mark- resight techniques (McClintock et al. 2009). Estimates of population size can then be used in conjunction with the amount of time that animals spent on the sampling grid to estimate the density of animals within the grid (White and Shenk 2001). Our objective is to outline a conceptual framework that can be used to estimate the super population size and density of mountain lions, which is part of an ongoing pilot effort that we conducted on the Uncompahgre Plateau, CO in 2009. The ultimate goal of our work is to demonstrate how reliable population estimates can be obtained through a mark-resight framework to inform future efforts that would conduct similar techniques across a broader spatial extent appropriate for mountain lions. Such information would be invaluable for managing and conserving mountain lion populations, especially those that experience harvest by sportsmen. STUDY AREA Our work was conducted in southwest Colorado on the Uncompahgre Plateau to the west of Montrose, CO (Figure 1). The area was characterized by mesas, canyons, and ravines, which 132
Session 5: WFA – Felid Population Monitoring supported forests of pinyon pine ( Pinus edulis ) / juniper spp. (western juniper, Juniperus occidentalis ; Utah juniper, Juniperus osteosperma ; Oneseed juniper, Juniperus monsperma ) and ponderosa pine ( Pinus ponderosa ), gambel oak ( Quercus gambelii ) thickets, and big sagebrush ( Artemesia tridentata ) flats. Cottonwoods ( Populus spp. ) occur in riparian areas and aspen ( Populus tremuloides ) stands were found at higher elevations. Figure 1. Study area where 40 motion-activated cameras across 2 sampling grids were maintained from 21 August to 13 December, 2009 on the Uncompahgre Plateau of southwest Colorado, USA. 133
Session 5: WFA – Felid Population Monitoring METHODS Camera Placement Our study site consisted of 2 grids of motion-activated cameras (Figure 1; area 1 = southern grid, area 2 = northern grid). Each grid was comprised of 20 sampling cells that measured 2 x 2 km. Our grid layout was designed to evaluate the occupancy of mountain lions and bobcats ( Lynx rufus ) and estimate density of bobcats. Within each cell, we placed 1 Cuddeback Capture white- flash motion-activated camera at a site that we believed maximized the opportunity to photograph both mountain lions and bobcats. Cameras were placed along game trails, people trails, and secondary dirt roads where felid sign was observed or in areas that appeared to be likely travel routes for felids. Our sampling was passive in that we did not use attractants (i.e., sight, sound, scent) to lure animals in front of the camera. Cameras were operational from August 21 to December 13, 2009. We visited each camera approximately every 2 weeks to replace memory cards and batteries if necessary. Marked Mountain Lions As part of an ongoing research project through the Colorado Division of Wildlife, mountain lions were captured with the use of hounds and cage traps for 5 years leading up to the camera study. Animals were fit with either GPS or VHF collars as well as eartags – we used these marks to assist in identifying individuals. GPS collars attempted a location every 6 hours and animals wearing VHF collars were located via aerial telemetry approximately every 2 weeks. Estimating Super Population Size and Density of Mountain Lions To estimate the super population size (number of individuals that used the sampling grids during the period of our camera surveys) we used mark-resight techniques and the Poisson log-normal mixed effects model (PNE; McClintock et al. 2009) in Program MARK (White and Burnham 134
Session 5: WFA – Felid Population Monitoring 1999). Assumptions of the PNE model included marking does not affect sightability, unmarked animals are counted as efficiently as marked animals, sampling with replacement, the number of marked animals was known, marked individuals were identified without error, and demographic and geographic closure during the primary interval. These recent mark-resight techniques extend Program NOREMARK (White 1996), where sighting information from marked and unmarked individuals is used to estimate the super population size. To estimate density of mountain lions on our camera grids, we used the amount of time that animals with telemetry collars spent on our grids (White and Shenk 2001). Therefore, our estimates of density are specific to the grid areas and we did not extrapolate our results out to a larger area. RESULTS We obtained a photo of a mountain lion at 23 out of 40 camera sites (area 1 = 11 out of 20 sites; area 2 = 12 out of 20 sites). Overall, we documented 80 photographs of mountain lions (area 1 = 39 photos; area 2 = 41 photos), with 50 photographs of marked individuals (area 1 = 17 marked individuals; area 2 = 33 marked individuals). Nine marked mountain lions were captured with our motion-activated cameras across our 40 camera sites. Four marked mountain lions used area 1 (3 GPS, 1 VHF) and 5 marked lions used area 2 (2 GPS, 3 VHF). Another marked female mountain lion used grid 2, but her GPS collar was not functioning during the camera survey. One male wearing a GPS used both areas 1 and 2. For the amount of time spent on grid, on average, mountain lions spent 12% of their time in area 1 and 30% of their time in area 2. The amount of time spent on grid ranged from 8% to 64% for individual mountain lions. 135
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