Males usually come into conflict due to competition for territories and females. However, interference competition can also occur between males of congeneric species when their ecological requirements are overlapping. Using acoustic playback experiments, we investigated male-male interactions within and between Grasshopper ( GW) and River Warbler (; RW). Our objective was to evaluate the song and behavioural response of tested males of both species to conspecific song stimuli in order to compare this with the response to congeneric stimulus, based on which we could assess whether these two commonly co-existing species show interspecific territorialism. A total of nine GW and 11 RW males were tested in May and June 2019 in western Slovakia. The ability to differentiate between the heterospecific (control), congeneric, and conspecific stimuli was similar between the two species. Conspecific playback elicited the strongest non-vocal response and a significant change in vocalization. The GW males shortened the songs, while the RW males shortened the songs and also increased their syllable rate. The congeneric playback elicited a lower intensity of behavioural response than conspecific playback and no change in vocalization in either species. We conclude that interspecific interference competition between GW and RW is rather low, suggesting that the species' ecological requirements are separated, although these two congeneric species commonly share habitat.

中文翻译：

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歌曲播放实验揭示了两种共存的蝗虫种内和种间的相互作用

雄性通常会因争夺领地和雌性而发生冲突。然而，当同属物种的生态需求重叠时，干扰竞争也可能发生在同属物种的雄性之间。通过声学回放实验，我们研究了蚱蜢 (GW) 和河莺 (RW) 内部和之间的雄性与雄性之间的相互作用。我们的目的是评估这两个物种的测试雄性对同种鸣叫刺激的鸣叫和行为反应，以便将其与对同属刺激的反应进行比较，在此基础上我们可以评估这两个常见共存物种是否表现出种间领土主义。 2019 年 5 月和 6 月，斯洛伐克西部共有 9 名 GW 和 11 名 RW 雄性接受了测试。两个物种区分异种刺激（对照）、同种刺激和同种刺激的能力相似。同种回放引起了最强烈的非声音反应和发声的显着变化。 GW男性缩短了歌曲，而RW男性则缩短了歌曲并增加了音节率。同种回放引起的行为反应强度低于同种回放，并且两个物种的发声都没有变化。我们得出的结论是，GW 和 RW 之间的种间干扰竞争相当低，这表明尽管这两个同属物种通常共享栖息地，但该物种的生态需求是分开的。