Grzegorz Neubauer, Małgorzata Bagińska, Urban Bagiński, Paweł Butkiewicz, Sebastian Guentzel, Łukasz Ławicki, Maciej Sobieraj, Marcin Sołowiej, Paweł Stańczak, Artur Staszewski, Arkadiusz Sikora
Ornis Polonica 2024, 65: 57–71
https://doi.org/10.12657/ornis.2024.1.4
Abstract: The Eurasian Woodcock Scolopax rusticola represents one of the few breeding species in Poland, for which the basic knowledge on population size and trends is missing. This is due to objective difficulties in reliable abundance assessments since the species requires dedicated methods – evening counts, which have not been performed on a wider scale so far. In addition, a proper way of dealing with count results is uneasy as they come with interpretation problems, mostly because male display flights cover unknown areas. In the present work, we propose a simple field method to count Eurasian Woodcocks and then modelling count results with a hierarchical N-mixture model to estimate abundance. The Eurasian Woodcock counts were performed in spring 2021 in Drawska SPA (1 539 km2, forest coverage 47%, Pomerania, Poland), with two 75-min long evening surveys in May and June, on observation points embedded in 40 randomly chosen 1 × 1 km squares. All display flights of males, with their exact times were noted by observers. The Eurasian Woodcock abundance in the whole SPA was estimated at 1 607 males in May (95% confidence intervals: 1 256–2 016) and 1 545 males in June (95% CI: 1 185–1 903). This estimate accounts for both the probability of a male being available for detection (estimated at 0.67 and 0.66 in May and June, respectively), related to temporary emigration (males make their display flights over bigger areas than covered with observations from the points) and the probability of detection itself (estimated at around 0.75). The key in the field protocol is to note exact times of each male Eurasian Woodcock flyover, allowing for a range of possible ways in modelling count results. The proposed method should allow for a better recognition of the Eurasian Woodcock population state and trends in Poland.
