Ziemowit Kosiński, Marcin Kempa, Przemysław Żurawlew
Ornis Polonica 2022, 63: 177–198
https://doi.org/10.12657/ornis.2022.3.1
Abstract: Analysis of population size and trends is an important step for the conservation and management of species of conservation concern in the Natura 2000 Special Protection Areas (SPA). In this study, we examined the population dynamics of the Middle Spotted Woodpecker Dendrocoptes medius and analyzed its trend in SPA Krotoszyn Oak Forest (KOF) (34,245 ha in size, including 14,757 ha of forest area) in 2010–2020. Furthermore, we attempted to identify which factors related to the area of different forest stands affect its abundance. We also investigated whether the changes in abundance of Middle Spotted Woodpecker in the whole KOF were similar to those occurring in a smaller part of this area (Łówkowiec Forest), in order to determine the usefulness of double sampling for the calibration of data obtained through periodic censuses. To estimate population size and determine the model describing the abundance of Middle Spotted Woodpecker, we used data from 19 randomly selected 1 km2 sample plots. Birds were counted most frequently during one or two surveys in each study plot using the call-playback method recommended for the censuses of the Middle Spotted Woodpecker. The estimated population size of the Middle Spotted Woodpecker in KOF varied between 587 pairs in 2010 and 823 pairs in 2015 and 2019. The non-significant trend suggests stable population. The rate of population growth between 2010 and 2020 was 1.338 (95% CI: 0.924–1.714), and the mean annual growth rate (λ) was 1.030 (95% CI: 0.992–1.055). The patterns of abundance index were generally similar in KOF and Łówkowiec Forest, except for the beginning of the study period. The abundance of the studied species was positively affected, with decreasing importance, by the area of three age classes of oak forest – ≥120 years, 80–119 years, and 40–79 years, and area of other deciduous stands; however, the effect of the last variable was very weak. Our data confirm that SPA KOF is the second most important area for the Middle Spotted Woodpecker, after the Białowieża Forest, in Poland. In the long run, the greatest threat for this woodpecker population in KOF could be uneven tree age distribution, with a disproportionate ratio of the old and middle age classes, especially in the Jasne Pole Precinct, fragmentation of old stands, and process of oak dieback which, in turn, can increase the intensity of sanitary felling and salvage logging. Our findings suggest that annual monitoring data from the Łówkowiec Forest could be useful to calibrate and improve interpretation of data from periodic censuses in KOF. This would reduce time needed for monitoring of birds using large-scale sampling.
Keywords: Dendrocoptes medius, double sampling, Natura 2000 Special Protection Area, population size, trend
