True cicadas (Cicadidae) as prey for the birds of the Western Palearctic: a review

Background:True cicadas(Cicadidae)are large and temporarily abundant insects.Their availability may produce demographic and behavioural effects on bird populations,as happens with forest avifauna feeding on periodical cicadas in North America.In Europe,the Near East and North Africa,knowledge of cicada predation by birds is sparse.Methods:To help fill this gap,I consulted Cramp’s Birds of the Western Palearctic,conducted a search of online databases and used search engines to generate a database of Western Palearctic birds known to eat cicadas.Results:A total of 105 species(16%of those occurring in the region)belonging to 13 orders,and comprising 20 of the 33 passerine families,were found to consume cicadas.I estimated that 69 of these bird species are known to consume cicadas within the limits of the Western Palearctic.Many terrestrial birds predate on cicadas,preferably on adults.Avian predators include cuckoos,owls,bee-eaters,woodpeckers,falcons,reed-warblers,larks,crows and jays,buntings,shrikes,pipits and wagtails,flycatchers and chats,tits,sparrows,leaf-warblers,starlings,warblers and thrushes,but also terns and gulls.Nymphs are consumed by some passerines,owls and herons.Cicadas can make up as much as 70%of food items delivered to nestlings.Analysis of stomach contents and neck collar samples are the most common methods used in diet studies.Conclusions:Available knowledge is biased towards species that have been more intensively studied,and often lack proper quantification of prey items.More studies about the relative importance of cicadas as prey for birds in the Western Palearctic are needed.I suggest using non-invasive studies based on pellets and droppings and prioritizing declining bird species.

The best of both worlds:cicada males change costly signals to achieve mates while females choose a mate based on both calling and courtship songs

Cicadas usually sing and mate in the higher parts of trees.Studies addressing the effects of different acoustic signals on mate choice in Cicadidae are very limited.We investigated the effects of both acoustical features and morphological traits on mate choice in an East Asian cicada Platypleura kaempferi.Males produce high-rate calling songs that attract females,then produce low-rate courtship songs to secure mating when a female is attracted.Higher calling song rate(CR),shorter single-pulse duration,and shorter pulse period of the calling song,together with lower courtship song rate and longer echeme period of the courtship song,are the most desirable traits used by females to choose a mate.These traits indicate that the more amale can raise the rate of song production,the higher the probability he is sexually selected by the female.No correlation was found between morphological traits and mating success.After mating,a minority of males started emitting calling songs again,but the CR was significantly lower than before mating and none of them attracted a new mate later.This promotes females mating with unmated males.We hypothesize that P.kaempferi may have the best of both worlds due to the unique song modulation and the mechanism of female mate choice:males change energetically,costly acoustic signals to achieve mates,while females choose a mate based on males’acoustic properties.Our results contribute to better understanding the diversity of mating preference and enrich the mechanism of mate choice in acoustic insects.

Females prefer males producing a high-rate song with shorter timbal-stridulatory sound intervals in a cicada species

Uncovering mate choice and factors that lead to the choice are very important to understanding sexual selection in evolutionary change.Cicadas are known for their loud sounds produced by males using the timbals.However,males in certain cicada species emit 2 kinds of sounds using respectively timbals and stridulatory organs,and females may produce their own sounds to respond to males.What has never been considered is the mate choice in such cicada species.Here,we investigate the sexual selection and potential impact of predation pressure on mate choice in the cicada Subpsaltria yangi Chen.It possesses stridulatory sound-producing organs in both sexes in addition to the timbals in males.Results show that males producing calling songs with shorter timbal–stridulatory sound intervals and a higher call rate achieved greater mating success.No morphological traits were found to be correlated with mating success in both sexes,suggesting neither males nor females display mate preference for the opposite sex based on morphological traits.Males do not discriminate among responding females during mate searching,which may be due to the high energy costs associated with their unusual mate-seeking activity and the male-biased predation pressure.Females generally mate once but a minority of them re-mated after oviposition which,combined with the desirable acoustic traits of males,suggest females may maximize their reproductive success by choosing a high-quality male in the first place.This study contributes to our understanding mechanisms of sexual selection in cicadas and other insects suffering selective pressure from predators.