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How sunrise and weather affect timing of rooks’ (Corvus frugilegus) morning departure from the winter communal roost
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SYSNO ASEP 0488422 Document Type J - Journal Article R&D Document Type Journal Article Subsidiary J Článek ve WOS Title How sunrise and weather affect timing of rooks’ (Corvus frugilegus) morning departure from the winter communal roost Author(s) Hubálek, Zdeněk (UBO-W) RID, SAI, ORCID Number of authors 1 Source Title Folia zoologica. - : Ústav biologie obratlovců AV ČR, v. v. i. - ISSN 0139-7893
Roč. 66, č. 4 (2017), s. 227-230Number of pages 4 s. Language eng - English Country CZ - Czech Republic Keywords animal behaviour ; chronobiology ; circadian rhythms ; environmental variables Subject RIV EG - Zoology OECD category Zoology Institutional support UBO-W - RVO:68081766 UT WOS 000447292200002 EID SCOPUS 85044213406 DOI 10.25225/fozo.v66.i4.a3.2017 Annotation The pattern of morning departure of rooks (Corvus frugilegus) from large communal roosts in winter is regular though it is affected by several environmental (weather) variables. A total of 151 records of the morning departure of rooks (and associated jackdaws, Corvus monedula) from two large communal roosts in the Czech Republic during the years 1966 to 1974 were analyzed. On average, the birds departed 36 min before local sunrise and 1.5 min after beginning of local civil twilight. Light intensity was the leading factor that explained 60 % of variability of the departure time. Cloud cover 30 min before sunrise, being interrelated with the light intensity at local sunrise, explained 52 % of the variability. Less important but significant factors were several weather variables such as precipitation, relative humidity of the air, horizontal visibility (fog), snow cover, and air temperature. Two best predictive multivariate regression models for timing of the birds’ departure involved factors: light intensity (that accelerated the departure) or inter-related cloud cover before sunrise (it delayed the departure), precipitation (delaying the departure), snow cover (accelerating the departure due to increased food demand), and horizontal visibility (fog delayed the departure). The two predictive multivariate models explained together 75 % of variability of the birds’ departure in relation to beginning of local civil twilight. Workplace Institute of Vertebrate Biology Contact Hana Slabáková, slabakova@ivb.cz, Tel.: 543 422 524 Year of Publishing 2019
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