Variations in the spring migration of Eurasian Woodcock (Scolopax rusticola L.) in Hungary

Abstract

We investigated the spatial and temporal patterns of migration of Eurasian Woodcock (n=23,539 specimens) collected in Hungary during spring sampling (2010–2019) in the framework of the Woodcock Bag Monitoring. There were differences in the temporal course of the spring migration of the species between the western and eastern regions of Hungary. In the western Hungarian counties, migration started earlier in all cases, while in Borsod-Abaúj-Zemplén county the main migration period – i.e. the period between the 25% and 75% cumulative sampling thresholds – started on average one week later than in Somogy county. We investigated the influence of weather factors on the spatial and temporal pattern of migration, in addition to geographical causes, based on the distribution of Péczely’s macrosynoptic situations recorded the week before and after the migration peak. In years free of weather extremes, the migration period was characterised by neutral (80.0%) macrosynoptic situations, with unfavourable (9.5%) and favourable (10.5%) conditions occurring less frequently. In the years with weather anomalies (2013, 2016, 2018), unfavourable macrosynoptic situations (81.3%) determined the spring migration characteristics. Weather anomalies (macrosynoptic conditions with gale-force winds and heavy snowfall) affected the timing of spring migration, but regional differences were observed in all years regardless of weather conditions, suggesting that spring migration of Woodcock is phase-delayed in the southern Transdanubian and north-eastern regions of Hungary.

An investigation into the possibilities of sex and age determination of Eurasian woodcock (Scolopax rusticola L.) based on biometric parameters, using conditional inference trees and minimal important differences

“…Age determination was carried out according to the widely used methodology for woodcock, based on the state and degree of moulting and the characteristic features (moulted or unmoulted) of each feather group (Glutz von Blotzheim et al 1977, Cramp & Simmons 1983, Ferrand & Gossmann 2009). The birds were separated into ‘juvenile’ and ‘adult’ age groups, with no further detailed classification applied (Bende 2021). The recording of biometric parameters (body weight, bill length, body length, wing length, tail length and tarsus length) and the choice of instruments used for measurement were in accordance with conventional ornithological methods.…”