Landform resources for territorial nettle-feeding Nymphalid butterflies: biases at different spatial scales

Abstract

Observations of perch sites for three territorial nymphalid butterflies reveals a bias in landform use at two spatial scales: at macro-scale, sunlit wood edges at the top of slopes; at micro-scale, molehills and bare ground compared to vegetation substrates. There is a hierarchy in landform exploitation; slope and edge position outweighsmicro-landform feature use. Landforms for territories tend to be prominent landmarks. This is especially the case at macro-scale (e.g., wood edges and corners); though also the case at micro-scale (e.g., molehills, earth bank edge) it is not invariably the case and highly apparent substrates (white boards) entered into territories were ignored. The predominant characteristic of all landforms chosen is that they are all hotspots: warm and sheltered sites. Substrates used for perching change with ambient conditions. In cool spring weather warm sites are essential for territorial defence, acquisition of females and predator evasion. As air temperatures increase there is an increasing propensity for territorial incumbents to use non-apparent, vegetation substrates. Bare earth sites are suggested to be important habitat components for butterfly biology as is their continued renewal through human activity.