Telemetry of Anisoptera after emergence first results (Odonata)

Abstract

The behaviour of Anisoptera during the period between emergence and the onset of sexual activity is poorly known, mainly because freshly emerged adults are hard to follow. In the present study the system RECCO® Transmitter/Receiver and custombuilt tags made from Schottky diodes and copper wire were used to monitor freshly emerged Anisoptera. The system had an average maximum detection distance of ca 85 m. Ten individuals of Libellula fulva were successfully tracked for up to five consecutive days. They almost exclusively utilized trees or shrubs as perches at heights ranging from 1.8 to ca 31 m. Open meadows or open river bank vegetation, which were present close to the release site, were never used for perching. Considering that human observers can reasonably detect adult anisopteran up to a height of 3 m, 92.5% of all registered perch sites were “out of reach”. The maximum distances covered on the first day averaged 37.7 m and 31.1 m for males and females, respectively. Two individuals, followed for four and five days respectively, remained in relatively small areas of 480 m² – 2,500 m² for three and four consecutive days. Five tagged individuals of Aeshna mixta showed a very different behaviour from L. fulva. Already in the first hours after release, all flew distances of more than 200 m and were lost. The telemetry system used was not suitable to study this species immediately after emergence.

Keywords: Odonata, dragonfly, Aeshna mixta, Libellula fulva, harmonic radar, telemetry, maturation

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