Season and temperature dependent location of mating territories in Somatochlora flavomaculata in a heterogeneous environment (Odonata: Corduliidae)


In a heterogeneous environment, males of Somatochlora flavomaculata regularly occupy site-fixed locations away from water, adjacent to vertical landscape elements, and to a lesser extent, also at water, i.e. at oviposition sites. Territories both over land and over water are typically patrolled by continuous site-fixed flights. These places serve as rendezvous sites where copulation is initiated. The results of a seven-year study in a heterogeneous mire habitat of Central Europe with scattered oviposition sites demonstrated that the rendezvous sites changed over the flight season in both location and quality. At the beginning of the reproduction period territories were established almost exclusively over land. Subsequently, there was a significant shift from sites over land to sites over water, and towards the end of the flight season virtually all territories were situated over water. Areas with overgrown puddles were also attractive for establishing territories, even at the beginning of the flight season. When the puddles desiccated during hot and dry spells in the first half of the reproduction period, these sites were no longer used as rendezvous sites. However, no shift towards territories over water was observed in this situation. Small-scale transfer of territories was also related to ambient temperatures. Below 28°C all males patrolled in full sunshine, but when temperatures rose they shifted their patrol sites gradually to the shade, presumably for thermoregulatory reasons. It appears that the mate search strategy of S. flavomaculata is characterised by extensive phenotypic plasticity with respect to time and space.

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