Doi: https://doi.org/10.13157/arla.72.2.2025.ra3
Authors: Tina PETRAS and Al VREZEC
E-mail: al.vrezec@nib.si
Published: Volume 72.2, July 2025. Pages 199-221.
Language: English
Keywords: Acanthis flammea, irruption rate, irruption trend, irruption years, long-term study, Loxia curvirostra and scaled mass index
Summary:
Bird ringing data allow continuous monitoring of birds while providing long-term time series that can be linked to anomalies indicative of one-off events such as irruptive movements. We analysed ringing totals over an 87-year period (from 1935 to 2021) for fringillid species in Slovenia (central Southern Europe) using a cross-section of multiple methods to detect irruption years. Our results showed that all fringillid species studied are prone to at least occasional irruptions (0.1 to 2.7 irruptions per ten years), these irruptions being more frequent in the boreal species that are highly irruptive (> 11% of irruption years in the 87-year period). Among the highly irruptive species, the number of irruptions is increasing for three species (Brambling Fringilla montifringilla, Red Crossbill Loxia curvirostra, Siskin Spinus spinus) and decreasing for two species (Redpoll Acanthis flammea, Hawfinch Coccothraustes coccothraustes). In addition, the body condition index clearly separated the irruptive and non-irruptive populations. The nomadic and irruptive species can form large but localised aggregations which are not stationary as in migratory species, but move and change from year to year, making the conservation of such irruptive flocks even more difficult. Thus, they require urgent conservation measures based on large-scale and long-term data. As bird ringing provides continuous, comprehensive and long-term data, it is potentially one of the most suitable methods for detecting irruptions and providing information on irruption dynamics.
Full Article:
Full Article
Supplementary Material:
Downloadable 1
