In late summer and during warm autumn days, the soundscape of Põõsaspea is dominated not by birds, but by much smaller creatures — the orthopterans. The largest families within this insect order are bush crickets Tettigoniidae and grasshoppers Acrididae. Distinguishing between the two families is actually quite simple. Bush crickets have antennae that are always longer than their body, while grasshoppers have much shorter antennae. The methods of sound production also differ between the families. Bush crickets produce sound by rubbing their wings together, whereas grasshoppers have specialized stridulation pegs on their hind legs that they rub against their wings to make sounds. The identification of species is usually easier based on sounds rather than appearance.

In Estonia, there are about 40 species of crickets. In the immediate surroundings of the Põõsaspea observation hut, at least seven can be encountered: bow-winged grasshopper Chorthippus biguttulus, common field grasshopper C. brunneus, steppe grasshopper C. dorsatus, golden grasshopper Chrysochraon dispar, upland green bush-cricket Tettigonia cantans, wart-biter Decticus verrucivorus, and dark bush-cricket Pholidoptera griseoaptera.

On sunny days, the bow-winged and common field grasshoppers sing in sparse vegetation or even on bare ground. The song of the bow-winged is a steadily increasing sizzle, while the common field grasshopper produces short splashing chirps. In denser vegetation, one can hear the steppe grasshopper’s pulsing and the wart-biter’s loud, rattling song. In tussocks of sand ryegrass Leymus arenarius, the golden grasshoppers hide with their somewhat quieter and short chirping song.

In the evenings, green bush-crickets start their performance with a relatively constant and loud chirping. As night falls, dark bush-crickets take over the singing, with their sporadic chirps sometimes heard even in November. While the other mentioned species can be found throughout Estonia, the upland green bush-cricket lives only in the mainland, and the dark bush-cricket is mainly found in western Estonia.

The songs of orthopterans can be heard on the following pages.
https://xeno-canto.org/collection/spotlight/134 https://loodusheli.ee/ET/loomaliigid/putukad/taxonid=308

Chorthippus biguttulus; bow-winged grasshopper; harilik rohutirts; ahoheinäsirkka (c) Anni Miller Chrysochraon dispar; golden grasshopper; kuldtirts; kultaheinäsirkka (c) Anni Miller Pholidoptera griseoaptera; dark bush-cricket; võsaritsikas; pensashepokatti (c) Anni Miller Tettigonia cantans; upland green bush-cricket; harilik lauluritsikas; idänhepokatti (c) Anni Miller Decticus verrucivorus; wart-biter; heinaritsikas; niittyhepokatti (c) Anni Miller

Suve lõpul ja soojadel sügispäevadel domineerivad Põõsaspea helipildis lindude asemel hoopis pisemad tegelased – sihktiivalised Orthoptera. Suurimateks sugukondadeks selles putukaseltsis on ritsiklased Tettigoniidae ja tirtslased Acrididae. Kahel rühmal vahet teha on tegelikult üsnagi lihtne. Ritsikatel on tundlad alati kehast pikemad, tirtsudel aga kõvasti lühemad. Ka heli tekitamise viisid on sugukonniti erinevad. Ritsikad laulavad tiibu omavahel hõõrudes. Tirtsudel on tagajalgadel aga spetsiaalsed piid, mida heli tekitamiseks vastu tiibu hõõrutakse. Liikide eristamine on enamasti lihtsam helide kui välimuse põhjal.

Eestis on umbes 40 liiki sihktiivalisi. Põõsaspea vaatlusonni vahetus läheduses kohtab neist vähemalt seitset: harilik rohutirts Chorthippus biguttulus, kahevärviline rohutirts C. brunneus, niidu-rohutirts C. dorsatus, kuldtirts Chrysochraon dispar, harilik lauluritsikas Tettigonia cantans, heinaritsikas Decticus verrucivorus ja võsaritsikas Pholidoptera griseoaptera.

Päikeselistel päevadel laulavad hõredas taimestikus või suisa paljal maapinnal harilik ja kahevärviline rohutirts. Hariliku rohutirtsu laul on ühtlaselt valjenev sahin. Kahevärviline rohutirts aga tekitab plärtsuvaid helisid. Tihedamast taimestikust kuuleb niidu-rohutirtsu vetruvat ja heinaritsika valju tärisevat laulu. Liiv-vareskaera Leymus arenarius tupsudes peidavad end pisut vaiksema ja lühildase lauluga kuldtirtsud.

Õhtutel saavad hoo sisse lauluritsikad, kelle laul on üsna ühtlane vali sirin. Öö saabudes võtavad laulujärje üle võsaritsikad, kelle üksikuid sirtsatusi võib kuulda veel isegi novembrikuus. Kui teisi mainitud liike võib kohata üle terve Eesti, siis harilik lauluritsikas on ainult Eesti mandriosas levinud ja võsaritsikat kohtab peamiselt vaid Lääne-Eestis.

Sihktiivaliste häältega saab tutvuda järgnevatel lehekülgedel.
https://xeno-canto.org/collection/spotlight/134
https://loodusheli.ee/ET/loomaliigid/putukad/taxonid=308

Anni