Impacts of the invasive European Starling on two neotropical woodpecker species: agonistic responses and reproductive interactions

ABSTRACT

The European Starling (Sturnus vulgaris) – hereafter ‘starling’ – has been introduced in many countries, and its South American population recently started expanding exponentially. This invasive species has a worldwide negative impact on the breeding performance of woodpeckers, competing for cavity use. Nevertheless, information is still lacking regarding southern temperate neotropical woodpeckers nest defence strategies and starling effects on woodpeckers’ breeding performance. We monitored Campo Flicker (Colaptes campestris) and Green-barred Woodpecker (Colaptes melanochloros) nests in a native southern temperate forest of central-eastern Argentina, to detect interactions with starlings and to assess the effect of starlings presence on woodpeckers’ breeding performance. We assessed whether woodpeckers perform defensive behaviours against the starlings by exposing taxidermied starling models to woodpecker breeding pairs. We detected interactions with starlings at 11% of the nests. These nests had a significantly higher probability of being abandoned during the early stages (until the third incubation day), compared to nests without interactions. Moreover, woodpeckers attacked and made distress calls more frequently in response to the presentation of the starling, compared to predator and non-competing species models. We also documented evidence of joint nesting, as four breeding pairs of woodpeckers shared their nest chamber with starlings. Our results indicate that neotropical woodpeckers are more likely to abandon their cavity when they interact with starlings. As the starling is expanding quickly in Argentina, this information points at the need to develop management programmes to control the impacts of this invasive species on the native fauna, especially on species with conservation concerns.

KEYWORDS:

• Cavity-nesting birds
• cavity usurpation
• Colaptes campestris
• Colaptes melanochloros
• invasive species
• neotropical region

Acknowledgements

We are thankful to M.L. Shaw for letting us undertake this study at the ‘Luis Chico’ ranch and to A. Mellum and L. González García for the help in data gathering. We are thankful to the three anonymous reviewers and two editors who made helpful comments on a previous version of this manuscript. We also thank P. Lowther for helping out through the Association of Field Ornithology Editorial Assistance Program. We appreciate the suggestions of T. Lansley and M. Fontaine.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Geolocation information

Punta Indio, Buenos Aires, Argentina (point): 35°20ʹS, 57°11ʹW.

Permit

This study was conducted with research permits from the regional nature conservation authority (Res. 003/16; OPDS #17717, Dirección de Áreas Naturales Protegidas, Buenos Aires province, Argentina).

Supplemental data

Supplemental data for this article can be accessed here.

Additional information

Funding

This work was supported by the ‘Fondo para la Investigación Científica y Tecnológica (Agencia Nacional de Promoción Científica y Tecnológica)’, under Grant number 2014-3347.