Context dependent effects on attack and defense behaviors in the praying mantis Tenodera sinensis

Impacts of predation risk on learning and memory of free-living mice

In predator-prey interactions, responses to predation risk typically involve behavioural, morphological or physiological changes. Laboratory-based studies have also shown changes in prey cognition (i.e. learning and memory), with individuals often showing impairment. However, an ecological perspective predicts that wild animals should conserve their cognitive ability, given that many risk responses require robust cognition. Here, we simulated predation risk and used a field-adapted version of the Morris Water Maze (MWM) to investigate how chronic predation risk affects cognition in wild white-footed mice (Peromyscus leucopus). We found that 24 days' exposure to predation risk did not impair learning. However, those exposed to risk had a 25% reduction of their short-term memory. Twelve days post-risk exposure, we found no performance differences between risk-exposed and control mice. Additionally, risk-exposed mice displayed greater exploration with a higher probability of completing the MWM in their initial trial. Given that prey integrate multiple pieces of information to shape their behaviour, the lack of learning impairment and altered exploration strategies may help mice respond to predation risk. However, the tendency of memory impairment suggests there are consequences for cognition when experiencing increased predation risk.

Opportunistic depredation of songbird nestlings by female praying mantids (Mantodea: Mantidae)

Praying mantids (class Insecta, order Mantodea) are a group of predatory insects comprising approximately 2500 described species, that occur across all continents except Antarctica, with the greatest species diversity in tropical and subtropical regions. Mantids predominantly prey on other invertebrates but are known to feed on small vertebrates. During April and May 2021, we observed mantid feeding events in Manujan County, Kerman Province in southern Iran. Two distinct feeding events were observed where female European Mantids (Mantis religiosa) preyed on Purple Sunbird (Cinnyris asiaticus) and Crested Lark (Galerida cristata) nestlings. In addition, we collated information from online searches of mantids feeding on nestlings elsewhere in the world, revealing two more observations. In Taiwan, a Giant Asian Mantid (Hierodula patellifera) was recorded preying on a nestling Warbling White-eye (Zosterops japonicus) and in Brazil, a mantid (Stagmatoptera sp.) was recorded feeding on a nestling White-throated Seedeater (Sporophila albogularis). To date, the only existing scientific evidence of praying mantids feeding on passerine nestlings was recorded in 1922. We propose two potential explanations for the observed trophic interactions between mantids and passerine nestlings: (1) during egg production female mantids, especially those in poor physical condition, may opportunistically feed on nestlings in order to increase fecundity via nutrient gain and (2) mantids may initially be attracted toward the nest by parasitic or coprophagous insects, as a result of poor nest sanitation, and subsequently prey on nestlings after detecting movements. Our unusual observations represent the first records of praying mantids feeding on nestling passerines in nearly 100 years.