Current status of the <i>Streptopelia decaocto</i> (Aves: Columbiformes) in Stavropol region
The Eurasian collared dove Streptopelia decaocto is a Palearctic species that demonstrates an example of intensive and rapid dispersal across Eurasia. At the same time, the expansion of the area is combined with its pulsation, and the reasons for this phenomenon are not completely clear. The Eurasian collared dove shows synanthropic tendencies and prefers to occupy residential habitats and agricultural landscapes when settling. Conservation status of the species according to the IUCN category system is LC: of least concern, but requiring further study and systematic monitoring. All of the abovementioned makes the study of the species very relevant. The aim of our research is to study the current state of the number, distribution and ecology of the Eurasian collared dove in Stavropol region. The studies were carried out in Stavropol region in 2008-2019 within geographical coordinates 43°43'-46°14'N, 40°51'-45°43'E in semi-desert, steppe and forest-steppe zones and foothills of the southern areas (See Fig. 1). We used methods of walking (over 500 km) and driving (42 000 km) route counts to estimate the population density, numbers of nesting birds, and their landscape distribution. This review also includes our results obtained during bird counts in Stavropol region in 2015-2018, as part of the program of the Atlas of breeding birds of Europe. In the course of this work, we examined 39 50x50 km squares. We studied the nesting biology of the species on the basis on discovering of 1167 breeding pairs, surveys of 490 nests and detailed observations of 58 nests. We conducted mapping of residential nests. Describing nesting structures, we noted the biotope, the species and height of the tree, the height of the nest location, the building material, the content of the nest, the presence and proximity of nests of other bird species, and we performed standard egg measurements. We determined if the breeding was successful by observations of nesting pairs in the period from the beginning of egg laying to the departure of chicks from nests. We studied the daily activity of the birds during the incubation period by visual observations for as long as 35+ hours. The Eurasian collared dove Streptopelia decaocto appeared in Stavropol region in 1973-1978 of the last century and has digested the entire area of the region as a result of intensive settlement. In general, we noted an increase in the nesting population of the species by almost one and a half times over a decade (47 thousand pairs in 2006 to 65 thousand pairs in 2019). The highest nesting population density of the Eurasian collared dove was recorded for the North and North-East of Stavropol region where animal husbandry predominates (See Fig. 1 and 2; Table 1). From the landscape point of view, the species clearly prefers the steppe province (0.27 pairs/ha), as well as semi-desert-dry-steppe (0.25); the density of its breeding population is lower in the forest-steppe (0.1); the lowest indicators are typical of foothill areas (0.05) (See Fig. 1; Table 1 and 2). As we showed in our research in the species’ biotopic distribution, the main types of its habitat are rural settlements, forest belts (protective, roadside) and forest plantations (plantings of nonlinear configuration of different areas) in agricultural landscapes. The Eurasian collared dove prefers eastern spruce (Platycladus orientalis) (21.4%) and common spruce (Picea abies) (9.6%) for nesting; in total, 20 species of tree species were used. At the same time, we observed atypical cases of nest placement (7.7% of all examined nests) on various residential buildings, power poles and other technical structures (See Table 3). We found the earliest clutches in the second decade of March, and the latest ones in late October and early November. The value of clutches amounted to an average of 1.57 eggs. The average size of the egg was 30.5 mm*24.6 mm (n=25). When observing the daily activity of the incubating females, we found that they spend 97.4% of the time on the incubation process (See Fig. 3 and 4). The Eurasian collared dove can make three or four clutches per season, while some of them may be repeated in case of poor nesting. Post-embryonic mortality in our studies was averaged 13.5%, often due to nest destruction by predators (mainly cats and grey crows), as well as due to adverse weather conditions. The Eurasian collared dove belongs to sedentary species, but at the same time, we observed mass autumn-winter roamings of the birds with the size of flocks of up to 500 individuals. We found that the limiting factors for the species are loss of clutches and chicks from predators and bad weather, as well as death of adult birds on the roads and as a result of abnormally low temperatures during winter. The results of our study confirmed the steady territorial expansion and growth of the Eurasian collared dove population in Stavropol region, mainly, due to the processes of synanthropization and urbanization and assimilation into agricultural landscapes. The paper contains 4 Figures, 3 Tables and 34 References. The Authors declare no conflict of interest.