There are approximately 2,500 species of praying mantis around the world, with representatives on every continent except Antarctica. These distinctive, generally large insects are well-known for predating other invertebrates, but they are also known to take small vertebrates such as lizards and fish at times.
However, the observation of female European Mantis taking nestling Purple Sunbird and Crested Lark in southern Iran prompted arthropologists to seek other reports of young birds falling victim to mantids. In both cases, the birds were at most at few days out of the egg and the whole event was observed, revealing that the mantids had been attracted by the movement of the nestlings. The sunbird nest was in a Ziziphus spina-christi (Christ's thorn jujube) tree, while the lark's was located at ground level.
Reports of nestlings being taken by praying mantids have emerged from Iran, Taiwan and Brazil (Gunjan Pandey via Wikimedia Commons).
This unearthed two further recent cases of young passerines being killed by mantids. The first was a Giant Asian Mantis taking a young Warbling White-eye in Taiwan, and the other involved an unidentified mantis feeding on a White-throated Seedeater nestling in Brazil. In these cases, both nests were in trees and involved older, feathered nestlings than the cases witnessed in Iran.
Experts proposed two possible explanations for these remarkable observations. It could be that female mantids are driven to take high-value food items like bird nestlings in order to gain enough nutrients to undergo egg production. Equally, the insects could end up at a bird's nest after following the movement of insects within it, and instead take the opportunity presented by the young birds. The latter scenario may be made more likely by poor nest sanitation, usually caused by the parent birds failing to remove faecal sacs.
Previous records show that at least three species of mantis are capable of taking adult passerines and hummingbirds in flight, often opportunistically during 'sit-and-wait' hunting.
European Mantis is considered an invasive species in parts of its range across Europe, Asia and North America, and it is known for being able to exploit new habitats. It is even the official state insect of Connecticut. It remains to be seen whether its ability to kill young passerines could present an unexpected conservation issue for vulnerable species.
Kolnegari, M, Fasano, A, Zareie, K, & Panter, C T. 2022. Opportunistic depredation of songbird nestlings by female praying mantids (Mantodea: Mantidae). Ecology and Evolution 12.12: e9643. DOI: https://doi.org/10.1002/ece3.9643