Complementation/supplementation of resources for butterflies in agricultural landscapes

Biodiversity conservation in agricultural landscapes is considered a challenge for nature conservation. The complementation/supplementation hypothesis may be an appropriate theoretical background for butterfly conservation in agricultural landscapes, by considering not only one patch but also several patches fulfilling various or similar ecological requirements. The aim of this article was to determine if butterflies' use of the landscape may be explained by this hypothesis. Two predictions of the complementation/supplementation hypothesis were tested: (i) butterfly "use" of herbaceous patches depends on the nature of the herbaceous patches and their management; (ii) butterflies stay preferentially in certain patch types. Mark-recapture experiments and behaviour recording were carried out in western France farmlands on Maniola jurtina. Herbaceous patches were grouped into six types: road verge, lane, hedge bank, grazed, mown and unproductive meadows. The first prediction was validated as butterflies did not use the different patch types in the same way. The road verge and lane were mainly used for feeding which is consistent with their high value of nectar abundance. Flying was the main behaviour expressed by butterflies in the unproductive and grazed meadows. When considering other activities than flying, the unproductive meadow was principally used for feeding and the grazed meadow for resting behaviour. The second prediction was confirmed as butterflies stayed less in grazed meadows and road verges than in lanes. Perspectives brought by complementation/supplementation hypothesis to conservation plans in dynamic farmland mosaics are discussed. (C) 2003 Elsevier B.V. All rights reserved.