All natural habitat edges matter equally for endangered Maculinea butterflies

Piotr Nowicki,Wiktor Halecki,Konrad Kalarus

doi:10.1007/s10841-012-9492-1

Piotr Nowicki, Wiktor Halecki + Show 1 more

Open Access

https://doi.org/10.1007/s10841-012-9492-1

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Abstract

An obvious consequence of habitat fragmentation is an increasing role of habitat edges for species survival. Recently it has been suggested that the endangered butterfly Maculinea nausithous prefers forested edges of its meadow habitats. However, the prevalence of forests in the study area used for this analysis makes it impossible to distinguish whether the effect detected is a genuine preference for forest edges or a preference for any natural patch edges as opposed to patch interiors. We investigated habitat selection by Maculinea nausithous and Maculinea teleius occurring sympatrically at five habitat patches surrounded by mosaic landscape. Butterfly capture positions were marked with GPS and subsequently analysed with GIS software. Both species avoided the interiors of their patches and concentrated in the edge zone, but these preferences were visible only at three larger patches exceeding 1 ha in area. Among different types of edges those bordering densely built-up areas were avoided, whereas all natural edges (adjacent to forests, reeds or grasslands) were similarly used. We hypothesise that preferences towards natural patch edges, regardless of their type, can be explained by the spatial interactions between Maculinea butterflies and Myrmica ants they parasitise. Patch surroundings constitute refuge space for the ants, and hence their densities may be expected to be higher near patch edges. Our findings indicate the importance of patch surroundings for the persistence of Maculinea populations. Regretfully, current legal framework makes it difficult to protect patch surroundings, where neither priority species nor their habitats occur.

Highlights

One of obvious consequences of habitat fragmentation is the fact that species experience edge effects more frequently (Primack 2002; Fahrig 2003)
We investigated habitat selection by Maculinea nausithous and Maculinea teleius occurring sympatrically at five habitat patches surrounded by mosaic landscape
An earlier landscape-scale study by the same team showed that M. nausithous concentrated along tree-lined edges of their habitat patches, whereas M. teleius was more abundant along road edges (Batary et al 2009)

Summary

Introduction

One of obvious consequences of habitat fragmentation is the fact that species experience edge effects more frequently (Primack 2002; Fahrig 2003). J Insect Conserv (2013) 17:139–146 meadow butterflies of the genus Maculinea (=Phengaris; while the latter synonym should have the priority, the use of the name Maculinea is allowed—see ICZN 2011, and we have decided to stick to it for the sake of consistency with earlier papers) Their findings indicated strong preference towards forest edges in M. nausithous (Bergstrasser, 1779), and lack of such preference in M. teleius (Bergstrasser, 1779). While we acknowledge the profundity of the results obtained in specific environmental context, we are not convinced about their generality, because the characteristics of the study areas did not allow to examine preferences towards other edge types This is true in the case of the study by K}orosi et al (2012), who worked in a region where Maculinea habitats were surrounded by forests and all the edges were forest ones. From the purely scientific point of view the distinction may appear minor, it has serious conservation implications, especially that Maculinea butterflies enjoy the status of flagships of biodiversity conservation in Europe and they are the target of a growing number of conservation programmes (Settele et al 2005; Thomas et al 2009, 2011)

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