ABSTRACT. Populations of Greater Prairie-Chickens (Tympanuchus cupido) have been declining because of loss and fragmentation of tallgrass prairie habitats, and management plans require contemporary demographic data. Our objectives were to determine whether maternal nutrition or predation were determinants of nesting success and female survival. We captured and radio-marked 43 females at four leks in natural, unfragmented prairie during a 4-year study. Reproductive potential was high because females laid large clutches (10.9 ± 0.3 eggs, n = 24), renested following clutch loss (22.2%, n = 27 females), and had high egg viability (88.6 ± 5.0% of eggs hatched; n = 7 nests), but reproductive traits were not correlated with female morphometrics (mass, or tarsus and keel lengths). Daily survival rate of nests was low (0.928, n = 34 nests) resulting in a predicted nest success rate of 7.4% for a 35-day exposure period. We used known fate models to estimate weekly survival from telemetry data for 40 females. Weekly survival was 0.970 and the extrapolated survival rate for the 6-month breeding season was 45.7%. Using time-sincemarking Cormack-Jolly-Seber models for live encounter data to control for transience, annual apparent survival was 0.277 ± 0.081 SE for 55 marked females after initial capture, and 0.424 ± 0.139 during subsequent intervals. Survival of females was 1.6 to 2.0 times higher during the nonbreeding season than the breeding season, presumably because females are susceptible to predation during incubation and broodrearing. Predation of nests and females may be the main demographic factors limiting population viability because predation, and not maternal nutrition, accounted for unexpectedly low nesting success and breeding season survival of Greater Prairie-Chickens in natural habitats. Future research should investigate rangeland practices that increase residual nesting cover or reduce predator impacts.RÉSUMÉ. Les populations de Tétras des prairies (Tympanuchus cupido) sont en déclin en raison de la perte et de la fragmentation des milieux de prairie à grandes graminées. Les plans de gestion doivent donc s'appuyer sur des données démographiques contemporaines. L'objectif de cette étude était de déterminer si l'alimentation des femelles et la prédation sont des facteurs importants du succès de reproduction et de la survie des femelles. Nous avons capturé et muni de radios 43 femelles provenant de quatre arènes dans des prairies naturelles non fragmentées, au cours d'une étude de quatre ans. Le potentiel de reproduction était élevé étant donné que les femelles produisaient de grosses couvées (10,9 ± 0,3 oeufs, n = 24), qu'elles pouvaient renicher lorsque la première avait échoué (22,2 %, n = 27 femelles) et que la viabilité des oeufs était élevée (88,6 ± 5,0 % d'oeufs éclos; n = 7 nids), mais ces paramètres de reproduction n'étaient pas corrélés avec les mesures morphométriques des femelles (masse, longueur du tarse et du bréchet). Le faible taux de survie quotidien des nids (0,928, n = 34 nids) s'est tradui...

Unmanned aerial vehicles (UAVs), or drones, are being utilized by wildlife biologists to monitor populations of birds and mammals. However, the reaction of wildlife to drones varies by species, so a preliminary evaluation must be conducted to determine if the target species can be detected via drone footage and to determine how the target species will react to drone presence. Lek-mating prairie-chickens (Tympanuchus spp.) seem amenable to drone-based surveys because they are relatively large and display in groups on elevated sites with sparse vegetation. The goal of our study was to determine what flight characteristics maximize prairie-chicken detection on drone video footage, to document the birds' reactions to the drones, and to compare how the noise produced by the drones compares to ambient sounds. We tested 3 sizes of rotary-winged drones, flown at 3 heights, with 3 different camera angles by flying over known prairie-chicken leks.We determined that >65% of prairie-chickens present were detected using video footage at a height of 100 m with a 10°c amera angle. Drones of different sizes had similar detectability. However, observers in blinds adjacent to leks routinely detected more birds than were detected on drone footage (detection on drone footage was 39.7 ± 9.6% of birds present).Prairie-chickens flushed in 96% of trials when a drone was flown over display locations. Time to return to the lek following drone disturbance was similar to prairie-chickens' reactions to natural predators. Prairie-chickens flushed when drone sound levels were comparable to ambient noise. Developing guidelines for the ethical use of drones in wildlife research will

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