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Article History

Received: 12 February 2026

Revised: 24 May 2026

Accepted: 27 May 2026

First Online: 3 June 2026

Declarations

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: The study was conducted in accordance with the Polish Act on the Protection of Animals (Journal of Laws 1997, No. 111, item 724) and with all applicable international, national, and institutional guidelines for the use of animals in research. The study involved standard ornithological field procedures, namely routine nest checks and observations of wild birds, without experimental manipulation or invasive procedures that would require separate approval from an animal ethics committee. Therefore, in accordance with national and institutional regulations, specific ethical approval for this study was not required. Nest collection permits were issued by the Regional Directorate for Environmental Protection in Poznań (WPNII.6401.265.2021.JM) and Warsaw (WSTS.6401.51.2021.MO).

: Nest attachment is a critical but under-described part of avian reproduction, particularly in human-modified farmland. As litter accumulates, plastic string may substitute for natural fibres as a functional“tying” element that stabilises open-cup nests. Monitoring 112 Red-backed Shrike ( Lanius collurio ) nests across three agricultural landscape types in Poland, we found that string-mediated attachment was common and closely tracked local litter availability within 20 m of nests. Attachment frequency and litter occurrence varied strongly among landscape types, peaking in intensive arable fields and lowest in meadows and mixed-crop mosaics. Attachment was unrelated to laying date, clutch size, or breeding success under broadly similar weather conditions. These results reveal behavioural flexibility in nest building and show how birds can use anthropogenic material to their advantage, suggesting that such materials are not necessarily harmful to birds or their nests.

: The authors declare no competing interests.