Sturnus vulgaris cooperative harassment and cavity usurpation, reproductive costs in Colaptes melanochloros

GERSTMAYER, PAULA A.; MONGES, VIRGINIA; JAUREGUI, ADRIÁN; COLOMBO, MARTÍN A.; LUCIANO N. SEGURA

Gramado

Congreso; Second Ornithological Congress of the Americas; 2023

Neotropical Ornithological Society & Association of Field Ornithologists

The European Starling Sturnus vulgarisis a cavity-nesting bird with great invasive potential. It is currently distributed across all continents (except Antarctica) and its distribution range is increasing at an alarming rate. It was introduced to Argentina in 1983 and is now widespread in the central region of the country. Considered one of the hundred most damaging invasive species globally, it poses a serious competitive threat to cavity-nesting birds. Interactions between European Starlings and cavity-nesting birds generally have negative consequences for native bird populations, although there are still few reports that account for the degree of damage. In this study, we present the first detailed account of the cooperative harassment strategy and subsequent cavity usurpation by European Starlings on a breeding pair of Green-barred Woodpeckers Colaptes melanochloros in an urban area of centraleastern Argentina. Throughout a single breeding season, the woodpeckers excavated seven cavities, none of which were successful. In six of these reproductive attempts (86%), we documented interactions with European Starlings and in five (71%), the cavity was usurped. We observed the cooperative harassment strategy on three occasions. Our report is particularly significant when considering the global invasive potential of the European Starling and the limited availability of cavities in the breeding habitats of native birds. If we extrapolate this cooperative agonistic behavior to the reproductive habitats of native cavity nesting species with a threat category, the consequences could be extremely serious.