Numbers of wintering waterbirds in the Czech Republic: long-term and spatial-scale approaches to assess population size

Abstract

Capsule Two nationwide monitoring schemes, the International Waterbird Census (IWC) and Atlas of Wintering Birds (AWB), provide comparable estimates of national population sizes of wintering waterbirds. Differences between these estimates for several species can be explained by differences in their migratory strategy. Aims We tested whether species-specific variables, i.e. the total numbers, distribution and migration strategy affected the accuracy of wintering population estimates provided by two different monitoring schemes, the IWC and AWB. Methods Estimates of the numbers of 81 waterbird species are compared, using data from IWC (mid-January) and AWB (December, January and February) in the Czech Republic between 1982 and 1985. Log-linear Poisson regression analysis was used to estimate missing IWC data from long-term IWC data series (1966-2013) using Trends and Indices for Monitoring data software. A series of generalized linear models was estimated to analyse the effect of species-specific variables on the presence of overlap between IWC and AWB national population estimates. Results The range of numbers recorded by IWC data overlap the range of AWB numbers in 22 of the 53 investigated species recorded by both monitoring schemes. Numbers of most other species based on the IWC counts were lower when compared with those generated from AWB data and included several widespread species, e.g. White-tailed Eagle Haliaeetus albicilla and White-throated Dipper Cinclus cinclus. In contrast, population size estimates based on IWC counts were higher than those generated from AWB estimates for one species, the Ferruginous Duck Aythya nyroca. The differences between IWC and AWB estimates were significantly higher in late-departing and early-arriving migrants. There was no effect of species distribution and population size. Conclusions Based on a single-country data sample, we support the relevance of the IWC Census methodology to produce estimates of wintering waterbird numbers and to calculate 1% thresholds for waterbird species, which we use to indicate nationally important wetland sites for future conservation and protection in the Czech Republic.

Changes in habitat suitability influence non‐breeding distribution of waterbirds in central Europe

“…Running water sites were defined as river sections with well‐defined boundaries, such as bridges, weirs or dams (Musilová et al . , , see also Chytil et al . for the list of wetland habitats in the Czech Republic).…”

Long-Term Changes in the Wintering Population of the Dalmatian Pelican along the Black Sea-Mediterranean Flyway

“…data) and the strict time-period of the IWC counts (i.e. mid-January), it is very likely that many birds might be counted already on their colonies or on their way to them (Musilová et al 2014) which could lead to rapid increases in the near future during the IWC counts as seen in those recently published for Iran (Ashoori et al 2019).…”

Changes in wetland habitat use by waterbirds wintering in Czechia are related to diet and distribution changes

“…swans, geese, ducks, grebes, cormorants, herons, rallids, waders, and gulls. However, in this study, we only include 25 the most common wintering waterbird species, namely those exceeding 50 individuals in Czechia annually (see also Musil et al., 2011; Musilová et al., 2014; see Table 1 for an overview of the species). We followed Gill and Donsker (2018) for the species taxonomy.…”