Two songbird species show subordinate responses to simulated territorial intrusions of an exotic competitor
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ORIGINAL PAPER
Two songbird species show subordinate responses to simulated territorial intrusions of an exotic competitor Pedro Filipe Pereira 1
&
Rui Lourenço 1 & Paulo Gama Mota 2,3
Received: 2 April 2019 / Revised: 1 June 2020 / Accepted: 9 June 2020 # ISPA, CRL 2020
Abstract Interspecific competition is rarely assessed between exotic and distantly related native species, although these can compete for some ecological resources. Here, we assessed the occurrence of interspecific aggression resulting from direct competition between two European native songbird species (henceforth focal species), the robin Erithacus rubecula and the blackcap Sylvia atricapilla, which are potential competitors for feeding resources and behaviourally subordinate to the exotic red-billed leiothrix Leiothrix lutea. In central Portugal, this exotic species lives in sympatry with robins and blackcaps at least since 2007. We used interactive playbacks to measure the behavioural response of blackcaps and robins towards intrusions by leiothrix and a submissive, native competitor—great tit Parus major. The singing behaviour of both focal species was affected by leiothrix playback. Robins exhibited a longer latency to sing, and both species avoided singing near the loudspeaker after leiothrix playback compared with great tit playback, which generally suggests a subordinate behaviour. Regarding changes in song parameters during the playbacks, only the peak frequency of blackcaps was affected by the playback. We discuss different possibilities for the origin of such submissive behaviour in native species. Keywords Aggressiveness . Competition . Introduced . Leiothrix lutea . Red-billed leiothrix . Song
Introduction Interspecific competition is an important factor affecting the distribution of species and the fitness of individuals (Freed and Cann 2009; Pigot and Tobias 2013). However, the cooccurrence of species is not a proof of the absence of competition between them, since overlapping interests will cause some sort of conflict (e.g. displacement of inferior competitors or competition for limiting resources; reviewed Responsible editor: Peter McGregor * Pedro Filipe Pereira [email protected] 1
MED – Mediterranean Institute for Agriculture, Environment and Development, LabOr – Laboratory of Ornithology, Instituto de Investigação e Formação Avançada, Universidade de Évora, Pólo da Mitra, Ap. 94, 7006-554 Évora, Portugal
2
Research Center in Biodiversity and Genetic Resources (CIBIO), University of Porto, Campus Agrário de Vairão, 4485-661 Vairão, Portugal
3
Department of Life Sciences, University of Coimbra, 3000-456 Coimbra, Portugal
in Amarasekare 2003). Often, between-species territoriality is also observed to mediate conflicts to obtain exclusive access to resources (Cody 1978; Losin et al. 2016). Some successfully established exotic species are dominant over native species and compete aggressively with them, which may result in species replacement in natural habitats (Gurevitch and Padilla 2004; Chapple et al. 2012; reviewed
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