Using demographic data to better interpret pitfall trap catches

Abstract

The results of pitfall trapping are often interpreted as abundance in a particular habitat. At the same time, there are numerous cases of almost unrealistically high catches of ground beetles in seemingly unsuitable sites. The correlation of catches by pitfall trapping with the true distribution and abundance of Carabidae needs corroboration. During a full year survey in 2006/07 in the Lake Elton region (Volgograd Area, Russia), 175 species of ground beetles were trapped. Considering the differences in demographic structure of the local populations, and not their abundances, three groups of species were recognized: residents, migrants and sporadic. In residents, the demographic structure of local populations is complete, and their habitats can be considered “residential”. In migrants and sporadic species, the demographic structure of the local populations is incomplete, and their habitats can be considered “transit”. Residents interact both with their prey and with each other in a particular habitat. Sporadic species are hardly important to a carabid community because of their low abundances. The contribution of migrants to the structure of carabid communities is not apparent and requires additional research. Migrants and sporadic species represent a “labile” component in ground beetles communities, as opposed to a “stable” component, represented by residents. The variability of the labile component substantially limits our interpretation of species diversity in carabid communities. Thus, the criteria for determining the most abundant, or dominant species inevitably vary because the abundance of migrants in some cases can be one order of magnitude higher than that of residents. The results of pitfall trapping adequately reflect the state of carabid communities only in zonal habitats, while azonal and disturbed habitats are merely transit ones for many species of ground beetles. A study of the demographic structure of local populations and assessment of the migratory/residential status of particular carabid species are potential ways of increasing the reliability of pitfall trap information.

Morphological variability of Bembidion aspericolle (Coleoptera, Carabidae) populations in conditions of anthropogenic impact

“…aspericolle is a Western Palearctic species (Sigida, 2009), living on the shores of the Atlantic Ocean, the Mediterranean, Black and Caspian Seas, and saline inland habitats from Central Europe to Central Asia (Hurka, 1996). It is distributed in Austria, Croatia, France, Germany, Georgia, Greece, Hungary, Italy, Kyrgyzstan, Kazakhstan, Moldavia, Romania, Russia (south part of the Russian plains; south part of West Siberia), Slovenia, Spain, Tajikistan, Turkmenistan, Ukraine, Uzbekistan (Ratti, 1983;Nitzu, 2003;Makarov & Matalin, 2009;Matalin & Makarov, 2011). It has not yet been found in the Czech Republic and Slovakia (Hurka, 1996).…”

Monitoring arthropods in protected grasslands: comparing pitfall trapping, quadrat sampling and video monitoring

“…Using these more sophisticated pitfall traps without preservative might then be more advisable in conservation areas in order to avoid potential killing endangered species through commonly used liquid preservatives (e.g. Schmidt et al, 2006;Calixto et al, 2007;Santos et al, 2007;Jud and Schmidt-Entling, 2008;Cheli and Corley, 2010;Schirmel et al, 2010;Matalin and Makarov, 2011). It has to be noted that due to the relatively short catching period in our study, slow-moving arthropods may be underrepresented (Topping and Sunderland, 1995).…”

“…Schmidt et al, 2006;Drapela et al, 2008;Zaller et al, 2009;Cheli and Corley, 2010;Schirmel et al, 2010;Matalin and Makarov, 2011;Frank et al, 2012;Hancock and Legg, 2012). This method is very attractive because it works when the observer is absent, it is very simple and inexpensive and it has been used in numerous studies (e.g.…”

“…This method is very attractive because it works when the observer is absent, it is very simple and inexpensive and it has been used in numerous studies (e.g. Prasifka et al, 2007;Cheli and Corley, 2010;Schirmel et al, 2010;Matalin and Makarov, 2011). However, pitfall traps are commonly filled with liquid preservatives that kill the collected animals (e.g.…”

“…However, pitfall traps are commonly filled with liquid preservatives that kill the collected animals (e.g. Schmidt et al, 2006; J. G. Zaller et al: Monitoring arthropods in protected grasslands Calixto et al, 2007;Santos et al, 2007;Jud and SchmidtEntling, 2008;Cheli and Corley, 2010;Schirmel et al, 2010;Matalin and Makarov, 2011) or lead to unwanted small mammal by-catch (Lange et al, 2011), which often prohibits the use of this method in protected areas where endangered species might get caught by this method. Alternatively, pitfall traps containing water only or no preservative at all were used (e.g.…”