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Keywords:

  • Minimum flight temperature;
  • thermoregulation;
  • thermoregulatory performance index

Summary

  • 1
    We examined the thermal ecology of Interior Alaska dragonflies (Odonata: Anisoptera). The relationships between mass and passive cooling rate, wing loading, minimum flight temperature (MFT) and thermoregulating ability were examined. These properties were also compared between the behavioural classes: perchers and fliers. All factors with the addition of seasonal and daily flight activity were related to generalized thermal strategies.
  • 2
    Passive cooling rate decreased while wing loading and MFT increased with mass.
  • 3
    While all species were able to elevate thoracic temperature, larger species were better able to maintain a constant temperature.
  • 4
    Both the smallest and largest species of dragonflies were capable of activity at ambient temperatures of approximately 14 °C by employing different thermal strategies: low MFT and physiological heat production, respectively.
  • 5
    For small species active in cool conditions low MFT may be favoured even if accompanied by poor thermoregulating ability. By contrast, thermoregulation and specialization for high-temperature performance may be favoured in both small and large species during the warmer summer flight season.
  • 6
    The smallest and largest dragonflies in Interior Alaska have the shortest and longest daily activity periods, respectively. However this pattern does not hold for the intermediate-sized dragonflies. Thermal strategy displays no clear relationship to daily activity pattern.