Observations on breeding Rosy Starlings in Bulgaria. Konstantin Nyagolov, Lyubomir Profirov, Tanyo Michev and Milko Dimitrov

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1 Observations on breeding Rosy Starlings in Bulgaria, Lyubomir Profirov, Tanyo Michev and Milko Dimitrov 178. Rosy Starlings Sturnus roseus, at breeding colony, Karnobat, Burgas region, Bulgaria, ABSTRACT Formerly regarded as an irregular migratory and breeding species in Bulgaria, Rosy Starling Sturnus roseus now occurs almost annually on the coast of the Dobroudzha region of northeast Bulgaria. In recent years, three regular breeding colonies have been located in the Burgas region of eastern Bulgaria.This species can now be considered an annual migrant, summer visitor and breeding species in Bulgaria. The Rosy Starling Sturnus roseus is an erratic, irruptive visitor to central and western Europe. Its breeding range extends from Central Asia to west and south Russia, and north to an as yet ill-defined limit. Occasional, irruptive range extensions of up to 1,200 km towards southeast and eastern Europe occur in spring, often in two or more successive years, with an 8-10 year periodicity, although the majority of these irruptive birds do not breed (Munteanu 1997). These irruptions are often attributed to localised abundance of insect populations, which are a key element of the Rosy Starling s diet; for example, Nankinov et al. (2000) related the huge invasion in 2000 to population levels of the grasshopper Dociostaurus maroccanus. In Bulgaria, Rosy Starling has traditionally been classified as an irregular migrant and breeding species. 242 British Birds 96 May

2 Observations on breeding Rosy Starlings Historical information on Rosy Starlings in Bulgaria Migrant populations and distribution The distribution of migrant Rosy Starlings in Bulgaria has been relatively well documented, and we traced 147 literature records for the period between the mid nineteenth century and Almost all of these sightings were made during spring migration, which peaks in the second half of May, and only five were of autumn migrants. In spring, flock size was typically between 50 and 100, although there was one observation of c. 500 birds. Surprisingly, there were no records of migrant Rosy Starlings on the southern Black Sea coast, south of Burgas. Based upon observations of spring migrants during the last 100 years, we conclude that the birds enter Bulgaria from Greece via the valleys of the Maritsa, Arda, Tundzha and Struma rivers, cross the Sofia plain and so reach the Danube valley. Flying east along this river valley, they reach south Dobroudzha. Here, the populations apparently divide, some continuing northeast into Romania while others fly south along the Black Sea coast and subsequently breed in the Burgas region. There is currently no knowledge of their return route in autumn. It is possible that this circular spring migration route is the result of the species historical breeding distribution. Breeding populations Known breeding localities are as follows (see fig. 1): 1. Sofia (and surrounding districts) Several colonies, numbering scores of thousands of birds, were reported in 1889; and a small colony near Pobit Kamuk in Subsequently, there have been no known breeding records in this area. 2. Northeast, Black Sea coast (Balchik-Tyulenovo) Prior to 1916, there were several records of breeding colonies, but the political history of this region resulted in a lack of information between 1916 and After 1940, a breeding colony of several hundred birds was found south of Balchik in 1951, a colony of 1,000+ individuals was reported at Cape Kaliakra in 1972, and four colonies totalling 1,780 birds were found in the region in East, Black Sea coast (Burgas region) As early as 1890, there were large flocks of Rosy Starlings and reports of breeding in this district (Reiser 1894). The first confirmed breeding colony in the region was discovered in 1994 by Nyagolov (1996), and recent observations lead us to conclude that breeding now occurs annually in this area. Breeding distribution of Rosy Starling in Bulgaria, Fig. 1. Location of breeding Rosy Starlings Sturnus roseus in Bulgaria during (blue dots), (green dots) and (orange dots). Large dots represent confirmed breeding, small dots represent possible breeding records. British Birds 96 May

3 179. Stone quarry, Karnobat, Burgas region, Bulgaria, 1996: a breeding site of Rosy Starlings Sturnus roseus. Recent data Breeding populations The discovery of a breeding colony in a stone pit near the town of Karnobat in 1994 led us to conduct a thorough search of suitable breeding sites in the region in subsequent years, which led to the discovery of further colonies, at Banevo and Chernivrakh (table 1). These colonies seem to be well established, and we believe that the Banevo colony has been occupied since 1960 (Mountfort & Ferguson-Lees 1961). Table 1. Numbers of breeding Rosy Starlings Sturnus roseus at three stone/rock quarries in Burgas region, Bulgaria, Counts are of numbers of individuals, not pairs. Year Karnobat Banevo Chernivrakh ?? ,000?? ,000?? ?? ?? ?? ,000 1,800 1, ,100 1, ,200 1,600 0 Our observations, particularly at the Karnobat quarry where Rosy Starlings have bred in every year since 1994, except , suggest that the species should no longer be considered irruptive in Bulgaria, but is better classified as an annual breeding visitor. Its breeding range now extends southeast to the Burgas region on the Black Sea coast, where all breeding colonies are in active or disused stone/rock quarries. Munteanu (1997) put the total number of breeding Rosy Starlings in Europe at between 500 and 2,500 breeding pairs. Our data suggest that this may be a considerable underestimate, and that there were approximately 5,160 breeding individuals in the Burgas region of Bulgaria alone in 2000, with 2,900 in 2001 and 4,800 in Food and feeding The principal diet of Rosy Starlings in Bulgaria consists of various species of grasshoppers (Orthoptera), as well as considerable vegetable matter, including fruits such as mulberries Morus, cherries, apricots and plums Prunus, figs Ficus and pears Prunus. In the summer of 2002, the two breeding colonies near Karnobat had a significant adverse effect on the quantity of fruit in surrounding orchards. In addition to that fruit eaten by adults, nestlings are fed with 244 British Birds 96 May

4 180. Adult male Rosy Starling Sturnus roseus, Karnobat, Burgas region, Bulgaria, stoned fruits. Adults may disgorge up to ten or more fruit stones at a time and these litter the entire area of the colony, while the rocks surrounding the colony are coloured rosy-white or red from the large quantities of excrement. Predators and other species Such concentrations of highly visible, noisy birds inevitably attract the attention of several predators, although the starlings often seem to pay no attention to a potential predator in their midst. All three colonies we studied were in quarries also occupied by nesting Eagle Owls Bubo bubo, but the starlings would alight on the edge of the eyrie even when occupied by nestlings or sitting adults and no interspecific reaction between the two species was noted. Peregrine Falcons Falco peregrinus were fre Juvenile Rosy Starling Sturnus roseus, Karnobat, Burgas region, Bulgaria, British Birds 96 May

5 182. Rosy Starlings Sturnus roseus, Karnobat, Burgas region, Bulgaria, quently recorded swooping upon the Karnobat colony, but only one successful capture was recorded and falcons alighting on the rock face near the colony were ignored. Acknowledgments The Bulgarian-Swiss Biodiversity Conservation Programme kindly provided the opportunity to carry out the field surveys. Kiril Bedev assisted with fieldwork, Stanislav Abadzhiev provided the UTM grid map,vladimir Pomakov translated the manuscript into English, and Bob Scott encouraged us and commented extensively upon the manuscript. Grateful thanks are expressed to all. References Mountfort, G., & Ferguson-Lees, I. J Observations on the birds of Bulgaria. Ibis 103: Munteanu, D Rose-coloured Starling Sturnus roseus. In: Hagemeijer, W. J. M., & Blair, M. J. (eds.), The EBCC Atlas of European Breeding Birds. Poyser, London. Nankinov, D., Dalakchieva, S., Popov, S. K., Kirilov, A., Iankov, P., Stanchev, R., & Shurulinkov, P Die Invasion des Rosenstares in Bulgarien im Jahre Orn. Mitt.: Nyagolov, K A breeding colony of Rose-coloured Starlings near Karnobat. Neophron 1: 12. (In Bulgarian) Reiser, O Materialien zu einer Ornis balcanica II, Bulgarien. Wien., Lyubomir Profirov, Tanyo Michev, Milko Dimitrov Burgas Wetlands Project, Bulgarian-Swiss Biodiversity Conservation Programme, PO Box 167, Burgas 8000, Bulgaria 246 British Birds 96 May