Introduction

During the last millennia, landscape cover has dramatically changed, and the structure and composition of the remaining semi-natural fragments has greatly altered over time (Lawton 1997). Exploitation of the landscape in the past resulted in a mosaic of temporally and spatially altering habitats. However, in the second half of the 20th century the landscape became largely homogenous and land use intensified (Hansson et al. 1995). Intensive agricultural and forest management affected many organisms. Farmers and foresters are being confronted with an increasing abundance of potential pests and conservationists are facing the decline of formerly common species. A general decrease in environmental heterogeneity leads to the absence of some types of habitats or even to broken metapopulation structure and increases the risk of extinction for habitat specialists (Matson et al. 1997).

There is growing worldwide evidence of ongoing change in the distribution of some species, including range extinctions and altitudinal shifts (Channell and Lomolino 2000; Sikes and Raithel 2002; Konvicka et al. 2003).

Beetles are often used in biodiversity studies, although only a few studies have dealt with habitat requirements (e.g. Horák et al. 2011). The rove beetles (Staphylinidae) are sometimes considered as bioindicators (Bohac 1999). Nevertheless, their taxonomy and lower rate of specificity to the (micro)habitat substrate make them very difficult to study (Bouchard et al. 2009).

The aims of our paper are to determine the altitudinal distributional pattern and habitat preferences of an endangered rove beetle Emus hirtus (Linnaeus, 1758; Coleoptera: Staphilinidae: Staphilininae) in the Czech Republic, the centre of its distribution area.

Materials and methods

Study species

The rove beetle Emus hirtus is a large (1.8–2.8 cm) and conspicuous beetle. This species is distributed in many parts of Europe, except the northernmost regions, and is also found in parts of Anatolia in Asia (Smetana 2004). This species was reported to be a habitat specialist occurs in low numbers only in long-term pastured areas with cattle dung and manure. Emus hirtus is one of the most impressive predators on Earth, foraging on other insects (Smetana 1958) and in the Czech Republic is red-listed as endangered following IUCN criteria (Farkač et al. 2005).

Study design and variables

We analyzed the dataset from Chobot (2010), which included all published historical records from the territory of the Czech Republic, supplemented with (published and unpublished) recent records. We determined the historical distribution (threshold in 1990, referred to as old) of Emus hirtus and compared this dataset with recent data (1990–2009, referred to as new). We chose the year 1990 based on the temporal absence in the modern distribution of the species in the study region (Kočárek 1997).

Faunistic records coming from non-systematic surveys are often spatially and temporally biased, which could compromise the description of the distribution and environmental responses of many endangered species (Dennis and Hardy 1999; Dennis 2001; Rocchini et al. 2011). Unfortunately, our data does not allow using the methods commonly used to determine whether there is any temporal bias in the altitudinal range surveyed (Lobo et al. 2007; Hortal et al. 2008). However, there is a long-standing tradition of beetle collection at the Czech Republic, and Emus hirtus is a large and conspicuous rove beetle species which is recorded almost any time it could be observed, being common in many private collections. In addition, there is a well-established tradition of sharing these collections with other collectors through local publications and, recently, through the internet via very active websites such as www.entoforum.cz. Due to this, we consider that it is highly unlikely that there is any significant bias in the altitudinal ranges surveyed at different times within the temporal range used for our analyses. Therefore, we consider that any change in altitudinal range measured with the records used in this work corresponds to actual changes in the altitudinal distribution of Emus hirtus.

The final dataset consisted of records of locality, year and GPS (Appendix). In the case of historical records we used GPS based on the location of the indicated locality. Some historical records had no indication of year, and thus we analysed them as old. All of them were certainly from the period 1900–1950. For further analyses we used only data with good descriptions of variables. Altitude, as the continuous variable, was measured using ArcView GIS (ESRi, Redlands, CA, USA), then log transformed to reach normality and tested with linear regression. Normality of dependent variables was tested with the Shapiro–Wilks test. Descriptive analyses were done with the parametric t-test and non-parametric Mann–Whitney U test for independent samples. All analyses were carried out using Statistica 7.0 (StatSoft, Tulsa, OK, USA).

Results and discussion

The rove beetles Emus hirtus experienced a sharp decline after the 1950s. There were only three records during the 1960s and 1970s and all of them were, surprisingly, from compensatory habitats such as carcasses and waste dumps (e.g. Jelínek 2001). Thus, the beetle was thought not to be a pasture specialist and able to exploit disparate habitat types like most other rove beetles (Kočárek 1997). For almost 20 years the species was regarded as regionally extinct in the Czech Republic. Nevertheless, from 1990 the species has been spreading throughout its distribution area (Gerend and Braunert 1997; Boháč et al. 2001; Telnov et al. 2005; A. Smetana, pers. comm.). Nowadays, Emus hirtus seems to occur in some sun-exposed localities at high population densities (Fig. 1a). Most of these sites are characterized as long-term and year-long cattle pasture with the presence of large amounts of cattle dung, although this dependence was not significant (Fig. 1b).

Fig. 1
figure 1

Altitudinal distribution and habitat requirements of Emus hirtus in the Czech Republic: a aspect (black colour is for presences and grey for abundance, cold is for NW, N, NE and E, warm for SE, S, SW and W aspect), b presence of long-term pasture and c altitude. Note that statistics in c is for log transformed altitude

Full size image

Our analyses showed that Emus hirtus has undergone an uphill shift from habitats in the lowlands and neighbouring areas (N = 15; Aveold = 309.3; Medold = 257.9; Minold = 188.6; Maxold = 490.2; SDold = 104.7 m a. s. l.) to the higher elevations of foothills and mountains (N = 20; Avenew = 485.4; Mednew = 437.0; Minnew = 240.6; Maxnew = 819.8; SDnew = 188.9 m a. s. l.). In the past, Emus hirtus, as a habitat specialist, preferred localities at lower elevations than in more recent times. This shift in altitude pre 1990 to post 1990 was significant (U = 60.0; Z = −3.00; P = 0.0027). The analysis of temporal distribution also showed that the species has probably shifted from lower altitudes to the mountains (N = 30; R = 0.46; R2 = 0.21; F = 7.48; P = 0.0107) over time (Fig. 1c).

It is possible that the uphill shift of Emus hirtus has been influenced by the loss of long-term pasture at lower altitudes and overall intensification in lowlands (Pysek et al. 2002; Konvicka et al. 2003) combined with past and recent changes in agricultural practices at higher altitude. Pastures were first abandoned after the Second World War at higher elevations due to the displacement of the German population and to early conservation measures which considered pasture as a harmful way to manage protected areas (cf. Krahulec et al. 2001). However pasture management systems are now more common at higher elevations (Hejcman et al. 2004), due to agri-environmental and LFA subsidies and the restoration of traditional management (Matějková et al. 2003), Emus hirtus could profit from this. Emus hirtus is one of many organisms characteristic of open pastured woodland landscapes in the past (e.g. Vera 2000). Changes in the altitudinal range of this species in the Czech Republic may be reflected in other species with similar ecological requirements.