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

Abstract

""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"

High-accuracy sampling of saproxylic diversity indicators at regional scales with pheromones: The case of Elater ferrugineus (Coleoptera, Elateridae)

“…The overall agreement between pheromone traps and pitfall/window traps was relatively high, indicating that both systems have good detection rates and between them present a near complete picture of the true distribution of O. eremita. This implies that O. eremita is generally over-sampled relative to other species when using pitfall and window traps, where the pitfall traps placed inside the hollow trees usually have a high probability of catching O. eremita, likely due to its sedentary ecology (Ranius 2001, Ranius & Nilsson 1997; but see Chiari 2011, Chiari et al 2013. In the present study, single pheromone traps were placed according to a fixed centroid position at each site, but the accuracy of the system could presumably be improved further, with negligible added effort, by placing multiple traps per site using and close to large hollow trees.…”

Monitoring and management of Cerambyx cerdo in the Mediterranean region – a review and the potential role of citizen science

“…Recent efforts in developing standard monitoring protocols for saproxylic beetles focused on applications of advanced statistical tools to address issues of insect detectability and to provide reliable estimates of distribution and abundance that can be compared across large spatial scales (Chiari et al 2013b, 2013a, Campanaro et al 2016. Several sampling methods have been applied to study C. cerdo populations, including visual censuses of adult exit holes to assess microhabitat requirements (Buse et al 2007, Regnery et al 2013, Albert et al 2013, Oleksa and Klejdysz 2017, comparison of evening transects, night surveys of trunks, pitfall and bait traps for distribution and population monitoring of adult beetles in a Natura 2000 network (Vrezec et al 2012) and bait traps to estimate dispersal in a Mediterranean woodland pasture (Torres-Vila et al 2017).…”

A Red List of Italian Saproxylic Beetles: taxonomic overview, ecological features and conservation issues (Coleoptera)

“…Only in the last decade we started to use capturemark methods to gather data on population abundance of some protected species in some Italian localities, and these data will represent a starting point for future research on demographic changes. For instance, the population density of Osmoderma eremita was estimated in southern Latium, in central Italy (Chiari et al 2013a), while abundance and survival probability of Lucanus cervus was calculated in a chestnut woodland of northern Italy (Chiari et al 2014a). Nevertheless, demographic data cannot be generalized at geographical or ecological level, because the quantitative parameters of beetle populations can vary enormously from a locality to another.…”