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Most Iberian jackdaws share winter roosts with other species

Close portrait of a Eurasian jackdaw
Research · Ecology

A census of 232 Eurasian jackdaw (Coloeus monedula) winter roosts across Spain and Portugal found that 71.6% were shared with other bird species. Shared roosts contained an average of 2.7 species and held significantly more jackdaws than roosts used by jackdaws alone.

The most frequent associates included other corvids, common starlings (Sturnus vulgaris), western cattle egrets (Ardea ibis) and common wood-pigeons (Columba palumbus). Jackdaws were numerically dominant in more than half of the shared roosts, although dominance varied with the identity and abundance of the other species present.

Roost sharing was more likely near landfills and in more urbanised landscapes. It became less likely with increasing elevation, greater annual temperature range and more forest cover around the roost, showing that the composition of the gatherings was associated with the surrounding landscape as well as with the birds themselves.

The presence of western cattle egrets, common wood-pigeons and starlings was associated with larger jackdaw roosts. Glossy ibis (Plegadis falcinellus) presence was associated with fewer jackdaws, while very high starling abundance was also linked to lower jackdaw numbers. The authors interpret the combined pattern as evidence that these interspecific associations are not random and can change with ecological context and crowding.

The researchers conclude that large communal roosts should be recognised as important ecological sites for overwintering bird communities. Their results emphasise that the value and functioning of a jackdaw roost can depend on both the wider multi-species assemblage and the landscape around it.

Sources and image credit

  1. Palacios-Martínez, I., Carrete, M., García, J., Alonso, H., Arizaga, J., Frías, Ó., Godinho, C., Hernández-Brito, D., Hortas, F., Martín-Zúñiga, J., Montoya-Ayala, R., Mouriño, J., Román Muñoz, A., Pérez-García, J. M., Prieta, J., Sanz, J., Solé-Bujalance, L., Travassos, P., Villanúa, D., & Zamora-Marín, J. M. (2026). Large-scale interspecific associations and ecological context shape communal roosts of Western jackdaw (Coloeus monedula). PLOS ONE, 21(5), e0346626. https://doi.org/10.1371/journal.pone.0346626Primary open-access study of 232 jackdaw winter roosts across Spain and Portugal, analysing roost sharing, associated species, abundance and environmental context.

Image: Jan Ainali / Wikimedia Commons — Eurasian jackdaw (Coloeus monedula) photographed in Karlstad, Sweden, 24 August 2008; representative species image; cropped to 16:9 · CC BY 3.0 — https://creativecommons.org/licenses/by/3.0/ · Source

About this content: This story was produced with AI assistance within an editorial workflow developed by Wildlife Vagabond. Editorial responsibility remains with Wildlife Vagabond.How AI is used

Ecology

SPECIES IN THIS STORY

Species in this story

Eurasian Jackdaw Coloeus monedula Explore species Western Cattle Egret Ardea ibis Explore species Common Wood-Pigeon Columba palumbus Explore species Common Starling Sturnus vulgaris Explore species

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