A European monitoring protocol for the stag beetle, a saproxylic flagship species

Abstract

Developing protocols for threatened invertebrates is often challenging, because they are not only rare but also elusive. This is the case with the stag beetle (Lucanus cervus), a protected and flagship species for the saproxylic beetle fauna in Europe. We applied a standard transect walk at a European scale (8 countries, 29 transects) to test its practicability and reliability as survey design. A total of 533 sightings were recorded throughout the sampling period, but detection probability changed as the season progressed. Considering the observed activity pattern, occupancy models showed that a short period of three consecutive weeks, between the middle of June and the first week of July, resulted in a high probability of detection (P > 0.7). As time of the peak of activity varies from year to year and between sites, we propose to extend the sampling period to five weekly surveys. Detailed information on the transect characteristics and the optimal time for surveying were analysed. The data indicate that a weekly transect at dusk provides a reliable method for monitoring this species throughout its distributional range. No correlation was found between latitude, longitude and phenology of sightings, however. However, a standard method such as the one presented, allows broadening the scale of monitoring studies, provinding data to evaluate the efficacy of conservation measures. © 2016 The Royal Entomological Societ

Can we successfully monitor a population density decline of elusive invertebrates? A statistical power analysis on Lucanus cervus

“…However, as these variables are likely to be related to temperature and none of them has been tested in combination with temperature, conclusions should be interpreted carefully. Finally, the stag beetles' activity is suggested to depend on the moon cycle (Mader 2009) but this has not been confirmed by Sprecher-Uebersax (2001) and Campanaro et al (2016).…”

“…The stag beetle is included in the second annex of the European Habitats Directive and consequently, species specific protection and monitoring is mandatory for every member state. As this species can only be observed during a very narrow time window (Campanaro et al 2016;Harvey et al 2011a), it can be argued that monitoring this species would yield insufficient data to evaluate its population trend. The stag beetle life cycle takes 3 to 5 years (Fremlin, Hendriks and Thomaes unpublished data, Rink and Sinsch 2008) which are spent mainly in underground dead wood.…”

“…After emergence, males live for about 8 weeks while females can live up to 12 weeks (Harvey et al 2011a). Even then, the species remains mostly hidden underground, being active during a short period around sunset (Campanaro et al 2016;Rink and Sinsch 2007). Furthermore, the activity of adults strongly depends on temperature (Harvey et al 2011a;Rink and Sinsch 2011;Sprecher-Uebersax 2001;Thomaes et al 2008).…”

“…Chiari et al 2014) and direct observations of living and/or dead beetles along transects (e.g. Campanaro et al 2011;Campanaro et al 2016;Fremlin and Fremlin 2010;Mader 2009;Sprecher-Uebersax 2001). Vrezec et al (2012b) found detection efficiency of evening transects (>90%) to be higher than that of trunk surveys and pit fall traps in the ground or attached to a tree (about 30-50%).…”

“…In most cases, a weekly follow up has been used with a fixed day (e.g. Campanaro et al 2011) or with a variable day depending on the weather (Campanaro et al 2016). Finally, it can be argued whether monitoring days should be concentrated around the short activity peak or over a longer period (Campanaro et al 2016;Fremlin and Fremlin 2010;Vrezec et al 2012a).…”