Within-habitat vegetation structure and adult activity patterns of the declining butterfly Euphydryas aurinia

Abstract

Background Euphydryas aurinia is a declining butterfly inhabiting oligotrophic grasslands in Central and Western Europe. Despite numerous ecological studies, patterns of its adult activity have so far been rather neglected, although adult resource use contributes to resource-based understanding of insects’ habitats. Aim To relate E. aurinia adult activity patterns to within-habitat vegetation structures. Methods (1) Timed adult activity observations along a transect crossing a colony site, analysed via partial ordination methods. (2) Activity records obtained during mark-recapture, analysed via binomial regressions. Results Both methods, besides influences of weather, time of day (similarities between morning and late afternoon hours), and progression of season (mate locating replaced by maintenance activities), revealed consistent association of behaviours to vegetation structures. Of the two male mate-locating behaviours, perching occurred near shrubs and woodland edges, and patrolling over centres of inhabited meadows. Female activity concentrated in nectar-rich mid-height sward near host plants. Consequently, male and female activity were partly spatially separated. Implications for conservation A habitat for E. aurinia should provide resources for all its activities in close proximity. Grasslands containing host plants should be dissected by structures such as shrubs, woodlot edges, or taller herbaceous vegetation, emphasising the importance of landscape heterogeneity for insect fauna.

Effect of mowing on population maintenance of the endangered silver-studded blue butterfly, Plebejus subsolanus iburiensis (Lepidoptera: Lycaenidae), throughout its life cycle

“…We found that the mowing conducted in this study did not impact the diversity of butterfly species or flowering plants (Table 1). Because mowing can regulate vegetation height (Tälle et al 2016), it may not always be beneficial for organisms that depend on specific fine-scale sites within semi-natural grasslands (Konvicka et al 2023). During our survey of the P. subsolanus larval stage, we observed markedly lower vegetation height in mowed sites than in unmowed sites.…”

“…The study site also served as a critical habitat for butterfly and flower communities in areas with low vegetation height. In addition, heterogeneous habitats with a mix of areas of low and high vegetation height have been shown to be important for grassland butterfly species, as males and females utilize areas of spatially distinct vegetation structure (Konvicka et al 2023). Therefore, although this study stressed the importance of low vegetation height areas in maintaining butterfly and flowering plant diversity, further research may clarify the contribution of high vegetation height to overall diversity and the number of P. subsolanus at this study site.…”

Novel grid‐based population estimates correlate with actual population sizes of the marsh fritillary (Euphydryas aurinia), while transect and larvae counts are less reliable

“…The grid method, hence, seem to be more reliable for both adult and larvae when it comes to detecting species occurrence. This is most likely because of its flexibility in where the surveyor spends most of its time, which makes it possible to better target local ‘hotspots’ for the availability of nectar resources and host plants (which also may vary between years), and vegetational structures that may affect their behaviour (Konvicka et al, 2023). We suggest that the grid method, due to its flexibility, also is less sensitive to species‐specific behaviour and appearance (Dennis et al, 2006; Kral‐O'Brien et al, 2020; Pellet et al, 2012), for example, in relation to sun exposure (Wittman et al, 2017) and different environmental conditions (Riva et al, 2020) that may affect the probability of species detection in a location at a given time.…”

Caterpillar loss through grassland harvest differs between two related butterfly species of conservation concern

“…They occur in nutrient-poor grasslands, in particular semi-dry calcareous grasslands, and E. aurinia can also be found in moist grasslands (Anthes, Fartmann, Hermann, & Kaule, 2003;Eichel & Fartmann, 2008;Konvicka et al, 2023;Scherer & Fartmann, 2022). The females of both species attach their egg batches to the underside of the host plants' leaves and prefer luxuriant plants for oviposition.…”

“…Nickerls Fritillary ( Melitaea aurelia ; Nickerl, 1850) and Marsh Fritillary ( Euphydyras aurinia ; Rottemburg, 1775) are closely related nymphalid butterfly species and specialised in nutrient‐poor grassland habitats. They occur in nutrient‐poor grasslands, in particular semi‐dry calcareous grasslands, and E. aurinia can also be found in moist grasslands (Anthes, Fartmann, Hermann, & Kaule, 2003; Eichel & Fartmann, 2008; Konvicka et al, 2023; Scherer & Fartmann, 2022). The females of both species attach their egg batches to the underside of the host plants' leaves and prefer luxuriant plants for oviposition.…”