Do predatory adult odonates estimate their adult prey odonates’ body size and dispersal ability to proceed with a successful attack?

Predator-prey encounters are one of the most challenging behaviors that animals engage in and play a key role in structuring trophic linkages within food webs. Empirical studies suggest that predators (except pathogens, parasites, and parasitoids) tend to be larger in body size and have better dispersal ability than their prey items; however, when predators prey upon members of the same taxonomic group, it is unclear whether such relationships exist between predators and their prey items since both groups may have similar body sizes and dispersal abilities. Adult odonates can be used to test this as they prey upon other odonates within the same suborder, family, genus or species, although such records are uncommon. Using a dataset collected from Sri Lanka and India from 2012 to 2020, this study identified three types of predation behaviors between two suborders of Odonata, i.e., (i) Anisoptera (dragonflies) prey upon Anisoptera, (ii) Anisoptera prey upon Zygoptera (damselflies), and (iii) Zygoptera prey upon Zygoptera. There was no evidence of Anisoptera predation by Zygoptera. Study results showed strong evidence that there is a significant difference in body size (i.e., body length) and dispersal ability (i.e., hind-wing length) between adult predatory odonates and adult prey odonates for all three types of predations. This may indicate that predatory odonates estimate other odonate prey precisely to proceed with a successful attack.