Associations between a range-shifting damselfly (Erythromma viridulum) and the UK’s resident Odonata suggests habitat sharing is more important than antagonism

Abstract

1. Species shifting their ranges under climate change are a conservation dilemma. Range-shifters may be threatened by climate change in their historic range. However range-shifters are likely to be generalist opportunists, which could mean they could harm aspects of biodiversity in their new ecosystems. Therefore, we need approaches to rapidly assess how range-shifters may integrate into the community of historically resident species.

2. The small red-eyed damselfly (Erythromma viridulum) has shifted into the UK since 1999, and may affect resident Odonata via intraguild predation. We asked whether the damselfly’s arrival is associated with a decline in resident Odonata.

3. We harnessed the British Dragonfly Society’s dataset, using records from 49,788 site visits between 2000-2015 to construct dynamic species occupancy models for 17 resident UK Odonata. We estimated the potential effect of E. viridulum presence on the probability that each species would persist at a given site, while controlling for potential effects of climate and recording effort.

4. On average, dragonflies (Anisoptera) persisted more frequently at sites where E. viridulum had established, whilst damselflies (Zygoptera) showed no change in persistence. Nevertheless, two resident damselflies, including E. viridulum’s congener, disappeared more frequently when the range-shifter established.

5. We suggest E. viridulum poses minimal risk to most UK resident Odonata. Rather, E. viridulum may be differentially establishing in areas with good habitat quality, where many species of historically resident Odonata are also found. Therefore, high quality, biodiverse sites may become home to increasing numbers of range-shifters in future. Our approach permits rapid-detection of how range-shifters are integrating into resident biota.