Factors influencing habitat choice of bird species: a comparative study of the ornithofauna of a natural and an artificial wetland

Abstract

Between 2019 and 2022, we studied the avifauna and environmental conditions of two wet-land habitats located in close proximity to each other in Transcarpathia (nearby to the village of Dyida, Zakarpatska Oblast, Ukraine)—one being a natural, currently protected but drying and highly degraded former bog (Tóvár Ornithological Reserve), whereas the other one being an ar-tificial pit lake (Lake Dyida). Lake Dyida is used as a beach and recreation area during the summer nesting season of birds. Both of these wetlands border with agricultural lands. Bird species that occur in both of the investigated habitats are affected by severe anthropogenic disturbances. A total of 27 795 individuals of 58 bird species from 34 families were observed in the two areas over the four study years. Results indicate that the species composition of the two study sites differed considerably, both on annual and seasonal basis. Seasonal precipitation totals strongly influence the current spatial ratios of terrestrial and waterbird species, and show a strong positive correlation with the seasonal total number of bird species. Maximum numbers of birds are recorded in spring and summer at Tóvár and in autumn and winter at Lake Dyida. In the case of Lake Dyida, these could partly be due to the autumn–winter appearance of migratory waterbirds and the end of the beach season. Despite the impact of numerous anthro-pogenic factors and habitat distrubances, the natural wetland is much more species-rich even in its degraded condition than the artificial wetland, which has been confirmed not only for bird species but also for plant species in the two areas. The obtained results revealed that duck spe-cies consider the deep-water pit lake as an alternative habitat during periods of drought, but for waders the great water depth makes this site less exploitable. In Europe, too, drying out due to seasonal precipitation shortages is an issue of increasing concern, especially for wetlands bea-cuse artificially maintained lakes and reservoirs cannot fully take over the role of natural lakes, marshes and bogs, which will have severe consequences for nature protection and species con-servation in the future.