Surveying an endangered saproxylic beetle, Osmoderma eremita, in Mediterranean woodlands: a comparison between different capture methods

""Measuring population size is riddled with difficulties. for wildlife biologists and managers, and in the. case of rare species, it is sometimes practically impossible. to estimate abundance, whereas estimation of occupancy is. possible. Furthermore, obtaining reliable population size. estimates is not straightforward, as different sampling. techniques can give misleading results. A mark-recapture. study of the endangered saproxylic beetle Osmoderma. eremita was performed in central Italy by applying four. independent capture methods within a study area where. 116 hollow trees were randomly selected to set traps.. Detection probability and population size estimates were. drawn from each of these four capture methods. There were. strong differences in detection probability among methods.. Despite using pheromone and beetle manipulation, capture. histories were not affected by trap-happiness or trapshyness.. Population size estimates varied considerably in. both abundance and precision by capture method. A number. of 0.5 and 0.2 adult beetles per tree was estimated using the. whole data set by closed and open population models,. respectively. Pitfall trap appeared the optimal method to. detect the occurrence of this species. Since in the southern. part of its distribution range, a single population of. O. eremita is widespread in the landscape, and includes. beetles from more than one hollow tree, conservation. efforts should focus not only on preserving few and isolated. monumental hollow trees, but should be extended to. large stands.. Keywords Coleoptera Scarabaeidae Conservation . Dead wood Occupancy Population size estimates . Sex pheromone"