Butterfly habitats, broad-scale biotope affiliations, and structural exploitation of vegetation at finer scales: the matrix revisited

1. Biotope and resources data are rarely attached to arthropod (butterfly) synoptic monitoring systems, and invariably not linked to behavioural exploitation of vegetation substrates. Yet, these data allow us to examine resource use within different biotopes and to distinguish more clearly between habitat and the matrix. 2. Comparative data on vegetation exploitation for different behaviours (search flight, direct flight, tactile inspections, perching, feeding, interactions, oviposition) were collected using transect sections over a range of biotopes from bare ground to mature woodland for two closely related satyrine butterflies, Maniola jurtina and Pyronia tithonus with overlapping flight times. Occupancy data were obtained on Pararge aegeria as a marker for the woodland end of the biotope spectrum. 3. There were clear distinctions in biotope occupancy between M. jurtina (grassland bias) and P. tithonus (shrub bias); significant differences in exploitation of vegetation substrates (except for nectar feeding) coincided with this bias in transect sections which comprise both grassland and shrubs. The exception (nectar feeding) is explained by the decline in shrub (Rubus fruticosus) nectar and increase in herb nectar during the later emergence of P. tithonus. 4. Direct flight increased in unsuitable biotopes for both species. However, resource-exploiting behaviour (>70%) predominated even in biotopes that would be regarded as completely unsuitable for supporting the species and where less than 2% of individuals for each species were observed. 5. Simultaneous collection of biotope, resources, and behavioural data is needed for monitoring affinities of butterflies to vegetation structures and using butterflies as indicators of environmental changes. 6. Much of the landscape is shown to comprise valuable resources for butterflies, even when classified for metapopulation studies as empty matrix.