Annual variation in harvested animals (hereafter bag size) is often used as an index of population abundance when investigating population dynamics. Few studies have evaluated how well bag size tracks population change despite its widespread use. Two recent studies on grouse harvest statistics have reached contrasting conclusions. Th ere is limited information about the functional response of hunters in relation to varying game densities, and effort is seldom recorded. We investigated how much of the variation in bag size (total number of harvested grouse km−2) is explained by variation in willow grouse Lagopus lagopus density (adult and young grouse km−2) and hunting eff ort (total number of hunting days km−2). We also evaluated catch per unit effort (CPUE) as an index of grouse abundance, and estimated the response in harvest rate (total bag size in relation to total grouse density) to varying hunting effort. We used data from the 88 management areas on state land in Jämtland county, Sweden (1996–2007), where hunting days and bag size are recorded in detail. Willow grouse density was estimated in four of these management areas in August using line transects and distance sampling. The hunting effort and total grouse density explained most of the variation in bag size (R2= 0.89). Bag size was twice as sensitive to changes in hunting effort compared to changes in grouse density. More than a ten times change in the grouse population density was required to one unit change in bag size. The use of CPUE did not provide a better alternative index of grouse density, and variation in density only explained 23% of the variation in CPUE. Harvest rate showed a strong relationship with hunting effort, and we suggest that an upper limit in hunting effort can be used to reduce the risk of high harvest rates. Hunters became more efficient at low densities and controlling hunting effort is most important when there are indications of population lows and/or poor breeding. CPUE may be less sensitive to changes in game abundance than previously assumed, and bag size as a proxy for population density would then depend on the ability of hunters to adjust their effort according to population change. We speculate that this ability will depend on whether or not hunters have long‐term experience of a hunting area where they can return to hunt throughout the hunting season. We propose that recording hunting eff ort should be encouraged and possible correlations with game abundance and other factors such as weather should be investigated for game species.

We analysed the spatial and temporal dynamics of chick production of willow grouse Lagopus lagopus in the Swedish and Norwegian mountain region using harvest data covering 24-38 years and line-transect counts covering 6-10 years from the period 1960-2003. Juvenile and adult grouse were counted in the bag of harvested willow grouse in late August and throughout September at six sites in Sweden and Norway. In addition, numbers of juvenile and adult willow grouse were obtained from line-transect counts at 21 sites in Sweden just before the hunting season started on 25 August. The juvenile:adult ratio from the harvest data, estimated as number of juveniles per two adults, showed similar long-term averages and distributions between all six sites. The results from the line-transect counts revealed an overall higher average and a greater range of production between sites. We suggest that the difference between estimates based on line-transect counts and harvest data are caused by hunter behaviour. Hunters did not sample the juvenile and adult grouse in proportion to what was present in the population, e.g., productivity estimates derived from harvest samples will underestimate the proportion of juveniles in autumn in most years. We suggest that it is the harvest process that acts to adjust the juvenile to old bird ratio in the harvest data to a similar distribution in different sites. We found little evidence of regular fluctuations/cycles in annual production of juveniles from either harvest data or line-transect data. We conclude that chick production in willow grouse appears to fluctuate more irregularly than was previously believed based on harvest data and can not be used as a potential forecasting tool in willow grouse management as suggested earlier. Spatial correlation was weak and investigating only a limited number of sites to predict the proportion of juveniles in autumn should not be considered as a management tool for large areas such as the state-owned land in Sweden. Line-transect counts are costly, but do provide a more accurate estimate of the proportion of juveniles in the fall population than is revealed by harvest data. A more detailed understanding of hunter behaviour is obviously needed for better interpretation of harvest data.

Age and sex ratios in bag records are frequently used as indices of population 18 composition for harvested populations. However, vulnerability to harvest may differ by age 19 and sex thereby producing bias in population estimates. We assessed whether age and sex 20 affected vulnerability to harvest for willow grouse (Lagopus lagopus) where adult density and 21 brood size was known in the harvested populations. We collected bag records during 2 days 22 of controlled hunting in 4 areas in 2 years (2007 and 2008) in Jämtland county, Sweden. We 23 found that vulnerability to harvest was different for chicks and adults, but not between male 24 and female adults. Hunters encountered broods at a higher rate than single birds compared to 25 personnel conducting pre-harvest counts along line transects. Furthermore, the probability of 26 shooting a grouse was higher in encounters of broods than individual grouse. Proportionally, 27we calculated about a 50% probability of a hunter shooting either a chick or an adult 28 1 E-mail: lasse.asmyhr@hihm.no 2 | Asmyhr et al.independent of encountering a single bird or broods of 2-10 grouse. Increasing adult density 29 also increased the vulnerability to harvest for adults relative to chicks, independent of the 30 chick to adult ratio in the pre-harvest population. The different vulnerability of adults and 31 chicks to harvest observed in this study will dampen variation in age classes in bag records 32 compared to the population, and we caution against extrapolation of age ratios in bag records 33 to harvested populations. 34 KEY WORDS age ratio, bag limit, harvest vulnerability, hunters, Lagopus lagopus, selective 35 harvest, sex ratio, willow grouse. 36

We investigated the general patterns of movements in willow ptarmigan (Lagopus lagopus) populations. We analyzed data from 300 radiocollared willow ptarmigan from 3 study areas in the Swedish mountain range, and from 2 previous studies of recoveries of wing-tagged chicks from 3 areas in southern Norway. We found that 80% of juvenile females dispersed more than 5 km from their natal area, whereas only 25% of juvenile males established a summer range more than 5 km from the area where they were caught as chicks. Mean dispersal distances of juvenile females were 3 times longer (10.4 km) than those of juvenile males (2.4 km). Movement differences within sexes were not associated with apparent female breeding success or ptarmigan density in the natal area, and adult females migrated between wintering areas used as juveniles and their first breeding site. We found no differences in dispersal distances between the Norwegian and Swedish populations. Movements of adult and juvenile females during spring were similar in all respects. At scales of more than 5 km, the movements of juveniles and adult females play a role in redistributing birds within landscape units, and represent important inter-population movements. The results of this study explain the apparent contradiction between non-compensatory mortality based on data from radio-marked ptarmigan, and the almost complete compensation based on annual counts. Estimating the extent of immigration into areas with high local mortality is difficult because of predation or harvest under conditions of high, fixed emigration and immigration dependent on local conditions. This represents a problem if dispersal distances include areas that are considerably larger than the size of the study area. Ó 2014 The Wildlife Society.

11Alpine and arctic tundra regions are likely to retract as a result of climate warming and 12 concerns have been raised over the status of the Rock Ptarmigan (Lagopus muta). In 13 Fennoscandia, the Rock Ptarmigan has low population abundance and predictions based on 14 harvest statistics show population declines throughout the range. In this study, we used a Ptarmigan during the breeding season. When planning conservation efforts, this information 27 2 should be used to inform management regarding the protection of core areas and buffer 28 zones related to the conservation and harvest management of the Rock Ptarmigan. 29