Document is current

Article History

Received: 27 October 2025

Revised: 21 April 2026

Accepted: 29 April 2026

First Online: 14 May 2026

Declarations

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: All bird manipulations (capturing, banding, blood sampling) and observations were authorized by the Junta of Castilla y León (first – last released licenses: EP/LE/177 -681/1999 – 2019) and followed the ASAB/ABS guidelines and the Spanish regulations for animal behavior research. No measurable adverse effects were detected. Adult crows were captured with walk-in traps that measured 120 x 45 x h 45cm, or with two snap traps that covered approximately 9 and 2 m2 respectively. The snaps traps were remote-controlled, and birds were removed within a few minutes. Walk-in traps were surveyed every 45-60 min to minimize the time spent in the cage. Neither trap type ever provoked injuries to the crows. The amount of blood extracted for sex determination (50 - 200 microliters) never exceeded 6% of the acceptable sample volume for every bird (Owen ). Wing tags did not significantly affect survivorship in our population (Canestrari et al. ).

: The authors declare no competing interests.