Аннотация:It has been generally believed that there exists an isolated breeding population of the Terek Sandpiper (Xenus cinereus) in Ukraine and Belarus; however a recent study suggested an uninterrupted breeding distribution in the species (Golovatin et al., 2010). This conclusion was based on several breeding records made in recent decades in the area between the main breeding range and the presumably isolated south-western distribution area. In our study we analyzed in detail the published sources, information from regional experts and some of our own observations made in the area under consideration. It turned out that in several cases information about breeding of Terek Sandpipers in the disputed area has been formerly interpreted incorrectly and in a couple of cases statements about breeding of the species were erroneous. Thus, we demonstrate a clear disjunction of ca. 400 km wide between the main breeding range across Eurasia and the population in the Middle Dnieper River basin that covers parts of Ukraine, Belarus and westernmost Russia. At the same time cases of breeding were documented for Latvia and Pskov Region in north-western Russia, and doubtful cases of breeding are known for northern Belarus (Fig. 1). While the species does display a degree of site fidelity, we consider these breeding records as examples of irregular adaptive dispersal of individuals within highly unstable breeding habitats.
