Eur. J. Entomol. 102: 699–706, 2005 ISSN 1210-5759 Adult demography, dispersal and behaviour of Brenthis ino (Lepidoptera: Nymphalidae): how to be a successful wetland butterfly 1 1,2 3 1,2 KAMIL ZIMMERMANN , ZDENċK FRIC , LADISLAVA FILIPOVÁ and MARTIN KONVIýKA * 1Department of Zoology, School of Biological Sciences, University of Southern Bohemia, Branišovská 31, 370 05 ýeské BudČjovice, Czech Republic 2Department of Ecology and Conservation, Institute of Entomology, Czech Academy of Sciences, Brani šovská 31, 370 05 ýeské BudČjovice, Czech Republic 3Department of Botany, Faculty of Sciences, Palacký University Olomouc, ŠlechtitelĤ 13, Olomouc, Czech Republic. Key words. Argynnini, Nymphalidae, Brenthis ino, behaviour, butterfly ecology, dispersal, habitat quality, grasslands, host plant range, metapopulation Abstract. Continent-wide loss of traditionally managed humid meadows is raising concern for associated butterfly specialists across Europe. However, not all species associated with this biotope are threatened, and the Lesser Marbled Fritillary (Brenthis ino) has even spread locally. We employed mark-recapture and transect walks to study its population structure and patterns of landscape occupancy in a hilly region of western Bohemia, Central Europe, to determine which life history or demography traits might be responsible for its success. A population studied by mark-recapture harboured more than 1000 individuals and was interconnected with other populations. This was further supported by a fit of the inverse power function to dispersal data. Observations of adult behaviour revealed a broad host plant range: at least three species of plants were used by the single population. On a landscape scale, the butterfly exhibited an aggregated distribution matching its host plants. It was associated with the distribution of characteristic plants and butterflies of semi-natural humid meadows, but its frequency exceeded those of other humid grasslands specialists. The relatively broad host range coupled with varying biotope requirements of individual host plant species results in a wide biotope range for the butterfly, explaining its persistence in fragmented Central European landscapes. INTRODUCTION The Lesser Marbled Fritillary, Brenthis ino (Rottem- Throughout Europe, agricultural intensification, irriga- burg, 1775), represents an apparently successful species tion and yield improvement schemes, and abandonment of humid meadows. Its distribution is stable in Europe. of less-productive land, have caused serious declines of Although it has disappeared from one country (the Neth- butterflies associated with traditionally managed humid erlands) and has declined in a few others, it is increasing meadows (Van Swaay & Warren, 1999; Maes & Van elsewhere, e.g., in the Czech Republic, Hungary, Slovakia Dyck, 2001; Beneš et al., 2002). Such losses urge the col- and Slovenia (Van Swaay & Warren, 1999). In the Czech lection of detailed ecological information on individual Republic, the increase is accompanied by colonisation of species that can be directly applied to practical conserva- previously unoccupied lowlands (Švestka, 1992; Beneš et tion measures (e.g., Neve et al., 1996; Fisher et al., 1999; al., 2002). The expansion has been attributed to expan- Anthes et al., 2003; Baguette & Schtickzelle, 2003; Kon- sion of its larval host plant, Filipendula ulmaria, facili- tated by abandonment of active management of riparian viþka et al., 2003; Schtickzelle & Baguette, 2004). The focus on declining species, however, results in neglect of grasslands (Švestka, 1992). However, the basic life his- butterflies that have evaded decline and have even spread. tory of the butterfly remains so little known that the Arguably, this restricts our understanding of species per- hypothesis remains unsupported. In any case, the increase sistence in fragmented landscapes. It is little known, for stands in striking contrast to severe declines of other spe- instance, whether species avoid decline owing to less spe- cies of humid meadows, such as Melitaea diamina (Lang, cialised requirements and hence access to a wider range 1789), Euphydryas aurinia (Rottemburg, 1775) and of biotopes, or whether they posses some demographic Lycaena helle (Denis & Schiffermüller, 1775) (cf. Beneš traits, such as better dispersal ability, which allows them et al., 2002). B. ino thus provides a suitable model for to track habitable areas more efficiently. In the case of studying mechanisms of persistence of specialised species widespread generalists, a combination of the above condi- in fragmented landscapes. tions may be responsible, although a denser distribution Here, we present results of a study on adult demo- of resources seems to correlate more commonly with suc- graphy of B. ino in a submontane landscape in western cesses (Sutcliffe et al., 1997; Schneider et al., 2003). The Bohemia, Czech Republic. It is based on a survey of the question is, what factors affect the apparent success of distribution of the butterfly in a section of landscape, non-declining specialists. mark-recapture study of adult demography, and records of adult behaviour and resource use. We ask, which life * Corresponding author; e-mail: [email protected] 699 history and demography traits might be responsible for the apparent success of B. ino in fragmented landscapes of Central Europe. By reporting our behavioural observa- tions, we also fill a gap in the basic knowledge of life his- tory of the species. METHODS Study species B. ino is a Palaearctic species distributed from W. Europe to the Ussuri region, N. China and Japan. Apart from the British Islands and extreme South, it inhabits entirety of Europe (Tolman & Lewington, 1997). Principal biotopes in C. and W. Europe include humid to wet grasslands, riverine marshes, bogs, clearings in wet forests, mountain valleys and subalpine tall- herb formations. In the Czech Republic, post-1980 distribution covers 270 grid squares, or 35% of the country (Beneš et al., 2002). Individual development is univoltine, adults are on the wing from late June until mid-August. Males use patrolling to search for females, females lay eggs singly and larvae feed solitarily. Regarding host plant use, there is contradictory information in the literature. The most frequently reported plant species are Filipendula ulmaria, Sanguisorba officinalis and Rubus spp., Fig. 1. Map of the study area showing the humid meadows but some authors mention Aruncus vulgaris, Potentilla palustris, where the mark-recapture study was carried out, and the four Sanguisorba minor, and a few other plant species (e.g., Hrubý, transect routes dissecting the meadows. Thick lines show seg- 1964; Henriksen & Kreutzer, 1982; SBN, 1987; Ebert & Renn- ments occupied by Brenthis ino. wald, 1991; Tolman & Lewington, 1997; Settele et al., 1999; Agnes, 2000; Sawchik et al., 2003). Hence, it seems that B. ino fragment size. As many butterflies as possible were captured is associated with various Rosaceae, perhaps with a trophic and marked with unique numbers; their sex, wing wear (1–4 range varying with geographic locality. scale, 1 being fresh and 4 being heavily worn) and position of Plant nomenclature follows Kubát (2002) and butterfly capture were noted before releasing them at capture points. We nomenclature follows Karsholt & Razowski (1996). also recorded behaviour prior to capture, distinguishing “flight”, Study area and design “patrolling” (searching flight distinguished in males only), bask- The study was carried in the vicinity of Karlovy Vary, ing, resting, egg-laying, mating and nectaring. For nectaring, we western Czech Republic (50°9´N, 13°2´E, altitude 650 m), on a recorded the plant used. hilly piedmont of the volcanic Doupovske Mts. The landscape is To estimate daily population sizes Ni, we used the analytical a fine-grained mosaic of both extensively used and improved Jolly-Seber method computed as model A in the program meadows, pastures, ponds, small woodlots and shrubby forest- JOLLY (Pollock et al., 1990). The method is appropriate for steppes on basaltic outcrops. Remnants of wet, extensively used open populations subject to births, deaths, immigration and emi- meadows constitute a Czech stronghold for several declining gration. The estimates are based on numbers of marked animals, butterflies, most notably Euphydryas aurinia (cf. Konviþka et estimates of daily residence (Mi – this combines survival and the al., 2003; Hula et al., 2004). probability of staying in a population) and daily numbers of ani- We conducted two parallel surveys in summer 2004. One was mals at risk of being captured. It does not return a “total” popu- a transect-based census of butterflies in a wider landscape, the lation size, which would be meaningless for open population other was a mark-release-recapture (MRR) survey of selected systems. colonies. The transects intersected the area of the MRR survey To estimate average residence, we used the variance weighted (Fig. 1), facilitating a comparison of the observational and MRR averaging (Tabashnik, 1980), which weights the JOLLY- results. estimated jis by the reciprocals of their standard errors V (Mi) K 2 Mark-recapture ( M c ) 1 / di [ V ( M c ) 1 / 2 ] ¦ i 1 i i M Vc K 2 The MRR study was carried out in a system of semi-natural V ( M c ) 1 / 2 humid meadows, separated by ponds, shrubby hedges and ¦ i 1 i woodlots. They are managed by mowing once a year, but less Average residence times (or “longevities”) were obtained as –1 accessible or waterlogged