Diel pattern of activity of Lestes macrostigma at a breeding site (Odonata: Lestidae) 00

Abstract

Monitoring methods always recommend gathering data during the maximal activity of adults. Hence monitoring the threatened Lestes macrostigma requires knowledge of its activity pattern. Dragonfly “activity” is ambiguous and its intensity can be assessed in different ways, including by the threshold of response to a predator stimulus, i.e. “awareness”. We studied the daily pattern of activity of L. macrostigma at the breeding site by monitoring the frequencies of behaviours, especially those of different flights, flight duration and speed, and awareness. We also assessed the abundance together with the probability to detect the species. The pattern of behaviour was characterized by reproduction but also feeding and roosting. Flight activity was more intense in early morning for males, around midday for pairs, and in the evening for males and females. Flight speed was highest around midday. These patterns were related to ambient temperatures and to a trade-off between the needs to mate and to feed. Awareness was almost constant all day long, suggesting new insights on daily activity variations in the Odonata, especially when perching. Slight differences between males and females indicated opposite trends. The pattern of abundance was singularly trimodal. This abundance depends on the true presence at the breeding site and to a probability of detection. The timing of monitoring is therefore not to be related to the activity per se, but to the abundance of adults. We recommend gathering data on L. macrostigma during early morning.

Keywords: Lestes macrostigma, Odonata, activity, diel pattern, flight, reproductive behaviour, postural adaptation, detection probability, survey, monitoring

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