Comparison of enumeration and Jolly-Seber estimation of population size in the common voleMicrotus arvalis

Abstract

2001. Comparison of enumeration and Jolly-Seber estimation of population size in the common vole Microtus arvalis. Acta Theriologica 46: 279-285.Capture-recapture data on common voles Microtus arvalis (Pallas, 1779) in central Europe have been almost exclusively analysed by means of the enumeration technique (minimum number alive or calendar of catches). Here we compare enumeration and Jolly-Seber (JS) estimation of population size in the common vole using live-trapping data from an alfalfa field-population in southern Moravia, Czech Republic. Over the entire study the enumeration estimate of the population size was smaller by an average of 28% than the JS estimate. The negative bias increased with density, decreased with both capture probability and the survival rate, and was more pronounced in males at high density. We conclude that the method of direct enumeration is not reliable for estimating population size in the common vole.

Preserving identity in capture–mark–recapture studies: increasing the accuracy of minimum number alive (MNA) estimates by incorporating inter-census trapping efficiency variation

“…While model selection with probabilistic approaches can determine the drivers of individual survival and detection (Laake et al 2013), eMNA directly connects individual persistence to population trends (Bright Ross et al 2020 and provides a robust abundance indicator for long-term studies. If eMNA is strengthened further by considering differential capture efficiency (and probability of persistence) as a function of prevailing conditions (Noonan et al 2015b), individual state markers (Noonan et al 2014), and population subgroups (Bryja et al 2001)-all of which can substantially affect recapture probability-enumeration approaches can continue to serve as a useful tool in wildlife studies, particularly integrated into ensemble approaches that make use of additional data not considered in these simulations. Individual heterogeneity in particular presents one of the greatest challenges to studying wild populations (Davis et al 2003), with individuals becoming trap-happy or trapshy as a result of any number of determinants (Byrne et al 2012).…”

“…Nevertheless, MNA's utility as an abundance indicator belies significant shortcomings when it is used strictly to estimate abundance. As already mentioned, MNA is a negatively biased estimator (Bryja et al 2001;Ramey et al 2008;Mullican, 2014); this bias is exacerbated under low capture efficiency (Hilborn et al 1976;Tuyttens 2000). Downstream metrics suffer as a result: MNA yields positively biased trappability (Byrne and Do Linh San 2016), and survival estimates based on MNA alone (implying immediate death after last capture, which is almost universally a poor assumption in an uncontrolled population) can lead to improper selection of covariates (Viallefont et al 1999).…”

Europe-wide outbreaks of common voles in 2019

“…They are a main food source for a variety of predators and provide important ecosystems services including seed dispersal, soil aeration and fertilization (Jacob et al 2014). However, during population Communicated by M. Traugott. outbreaks that occur generally in a cyclic manner about every 3-5 years (Tkadlec and Stenseth 2001;Cornulier et al 2013), populations can reach densities of > 2000 individuals per hectare (Bryja et al 2001), which leads to enormous damage to millions of hectares of agricultural and forestry crops in the European Union (EU) (Lambin et al 2006;Luque-Larena et al 2013).…”

Variation in the diet and breeding biology of the Common Barn-owl (Tyto alba) in a demographic cycle of Common Vole (Microtus arvalis) between two outbreaks×

“…Considering the European agricultural landscape, the Common Vole (Microtus arvalis Pallas, 1778) is the most abundant and widespread microtine rodent species, and due to high overshoots of carrying capacity (Bryja et al 2001, Jacob & Tkadlec 2010, Common Voles cause significant damage during outbreaks (Lambin et al 2006, Jacob et al 2014. Population dynamics of the Common Vole is characterized by multiannual fluctuation with 3-5 year-long population cycles in agricultural fields (Tkadlec & Stenseth 2001, Lambin et al 2006, Cornulier et al 2013, Luque-Larena et al 2013, Jacob et al 2014 and it shows typical well-defined and separable demographical phases, such as long intervals of low abundance (crash phase), increase phase and short intervals of peak phase (outbreak) (Tkadlec & Stenseth 2001, Lambin et al 2006.…”