In May and June, a comprehensive dataset on the birds feeding was collected from the grasslands of Western Estonia. The aim was to find out how the ecological condition of the grassland and its location on the landscape affects the species composition of the birds, the number of individuals and the diet of the birds was investigated. For this purpose, a point count of birds, bioacoustic monitoring, collection of the main food base of grassland birds (arthropods) was done and also birds were captured to collect excrement. For bioacoustic monitoring, compact audio recorders (AudioMothTM) were used to record the richness of morning songbirds. To estimate the biomass and species richness of arthropods, cups were dug into the ground, and the sweet liquid they contained lured the arthropods into the cups. To prevent rainwater accumulation, the cups were covered with a special wooden roof. The species composition of arthropods can be known later through DNA analyses.
The most labor-intensive were the attempts to catch birds. For this, birds were caught from sunrise to mid-morning with a special bird-catching net, and fresh bird droppings were searched for in the grasslands. As a rule, birds excrete after entering the net, and the obtained excrement was placed in cups filled with ethanol using sterile means. Later DNA analyzes will reveal what the birds consumed as food from the grasslands and whether the condition of the grasslands affects the birds' food base. To maximize the capture efficiency, all captured birds were ringed.
125 birds from 24 different species were caught and ringed during the capturing tests. In addition, we collected 80 fresh droppings left by birds from grasslands. The most numerous of the birds caught was the little bush bird (Sylvia curruca), which is one of the most numerous nesters in the grasslands and the surrounding shrubbery. Hollow-nesting white-backed woodpeckers (Dendrocopos leucotos), wrens (Jynx torquilla) and various species of tit were also caught in the net - such species diversity shows that it is a rich and diverse grassland. We also succeeded in catching and ringing an endemic species of the grazed hemlocks in western Estonia - the striped bushbird (Sylvia nisoria). Molecular analyzes will show what the diet of these species consists of.
