A large scale survey of the great grey shrike Lanius excubitor in Poland: breeding densities, habitat use and population trends

摘要

The great grey shrike Lanius excubitor is declining in western Europe but relatively stable, or even increasing populations still exist in central and eastern Europe. It is a medium-sized passerine living in diverse, low-intensity farmland. Being a predatory bird, it is especially susceptible to any changes in farming practices that affect its prey. In this paper, we provide estimates of density, national population size and trends and generate a habitat-use model; information which is all necessary for effective conservation. We used data gathered during 71 censuses made in the years 1978-2005 to document the past and present status of the great grey shrike population in Poland. The mean population density has more than doubled from 4.5 in the early period of the study (1978-1995) to 11.3 pairs/100 km2 in the later period (1996-2005). The habitat use model shows that the great grey shrike avoids intensive arable fields and coniferous forests and prefers areas of extensively used farmland. We estimate the current size of the Polish breeding population to be 22 000-25 000 breeding pairs. Our results show that the Polish breeding population of the great grey shrike is still healthy. This can be attributed to high habitat heterogeneity and fragmentation, a slow rate of change in agricultural landscapes and recent mild winters which have had a ositive effect on survival. We believe that our results can help to establish an effective conservation strategy for the species.