The distribution of Great Grey Shrike in Republic of Moldova

Abstract

The Great Grey Shrike (Lanius excubitor) is the largest species from the Laniidae family, with a wide distribution in the Northern Hemisphere, across Europe, Asia and North America. Because the species occupies a large area, the data about the spring and autumn migration and wintering areas of the whole population is poor documented. The study area covers the territory of the Republic of Moldova (33 843.5 km2). Here, the Great Grey Shrike was known as a wintering visitor, being recorded during the late autumn up to early spring. The species was not considered to breed until now in the Republic of Moldova, therefore it was not listed in the Bird Atlas. Even today, the Great Grey shrike is a poorly studied species in our country and there is no up-to-date information except the actual study. The first breeding recorded was in 2012 in the north region of the country. After that, we started a monitoring program in order to check the species’ status.

The aim of the current study was to assess the distribution of the Great Grey Shrike in the Republic of Moldova and to analyze the breeding and wintering population. The study was conducted from 2014 to 2017. During two breeding seasons (2014 and 2015) we carried out point counts with a minimum distance of 400 m between them and 5 minutes of observation in each location.. The observation points were randomly selected across the study area using Hawths Tool for Arc GIS v.9.3. In 2014 we registered 20 breeding pairs out of 470 observations and for 2015 we counted 31 breeding pairs out of 631 observation points. The density of the Great Grey Shrikes in Republic of Moldova estimated, for the research period, to 0.2-0.4 breeding pairs/square km. According to our study, its breeding range is increasing (occupying 75% of the country), extending to south, contrary to previous conclusions which stated that the population is concentrated in north. The GLM analysis showed that the great grey shrike breeds in areas with higher altitudes (a mean of 174 m), low level of precipitation in November and with low average temperatures (all P< 0.05).

To estimate the wintering population, we used the line transect method. Monthly, we conducted 9 transects about 40 km long each (360 km per month), during November - February, for two seasons, 2015 – 2016 and 2016 –2017. The method consists in driving a car at slow speed (up to 40 km/h) with very short stops, if is necessary. The distribution across the country was uneven, 42 were observed in northern area, 37 in the central one and only 5 in south. The numbers of individuals in the first wintering season was 46, while in the second there were 38 individuals counted in Republic of Moldova. According to Manly’s selectivity index the Great Grey Shrike select during winter season orchards (Wi= 1,6) and grasslands (Wi= 3.0). The data collected during the winter season shows that birds tend to keep their breeding spots, being recorded near them during this harsh season.