Funding for this research was provided by:
Natural Environment Research Council (NE/S00713X/1, NE/R001669/1)
Article History
Received: 16 May 2023
Revised: 29 August 2023
Accepted: 5 September 2023
First Online: 15 September 2023
Declarations
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: During nest building, laying and incubation each nest was checked every 1–3 days, with daily checks approaching laying, incubation and hatching. Whenever possible nests were sampled non-intrusively, <i>e.g.</i> incubation confirmed by observing females’ attendance at the nest. However, to record precise hatch dates, after 12 days of incubation, nests were checked daily for hatching by feeling gently within the nest, a practice that has been performed on this population for 29 years. Nestlings and adult immigrants were ringed by BJH and SJB under British Trust for Ornithology (BTO) Licence with two colour rings (size code: XF) on one leg and a metal BTO ring (size code: AA) on the other. When ringing nestlings, to minimise time chicks spent out of the nest and to ensure that carers did not return to an empty nest, half the brood was ringed at a time. During ringing, 5–20 µl of blood was taken by brachial venepuncture under UK Home Office licence (Project Licence PP5912664; Personal Licence (BJH) IE73AE8C8) for genotyping and sex determination. During sampling, nestlings were stored in an insulated bird-bag and remained warm and dry throughout. In total, 183 nestlings were ringed from nests sampled for this study. When ringing adult immigrants, mist-nests were watched continuously, and birds were extracted and processed immediately upon capture. In total, 21 breeding females, 20 breeding males and 11 helpers (10 males, 1 female) were observed in this study. Our experimental procedure necessitated some observer disturbance when setting up the camera and presenting models, however, we recorded no events of brood abandonment during or following our experiment. All applicable international, national, and institutional guidelines for the use of animals were followed and all regulated procedures were approved by the Animal Welfare and Ethical Review Body at the University of Sheffield.
: The authors have no competing interests to declare that are relevant to the content of this article.