Observations on breeding Rosy Starlings in 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. T he 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.

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242 © British Birds 96 • May 2003 • 242-246
178. Rosy Starlings Sturnus roseus, at breeding colony, Karnobat, Burgas region, Bulgaria, 1996. Konstantin Nyagolov
Observations on breeding
Rosy Starlings in Bulgaria
Konstantin Nyagolov, Lyubomir Profirov,
Tanyo Michev and Milko Dimitrov
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.

243British Birds 96 • May 2003 • 242-246
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
1992. 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 typi-
cally 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 thou-
sands of birds’, were reported in 1889; and a
‘small’ colony near Pobit Kamuk in 1920.
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 1940. 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 Kali-
akra in 1972, and four colonies totalling
1,780 birds were found in the region in 1975.
3. 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.
Fig. 1. Location of breeding Rosy Starlings Sturnus roseus in Bulgaria during 1893-1920 (blue dots),
1950-75 (green dots) and 1994-2002 (orange dots). Large dots represent confirmed breeding,
small dots represent possible breeding records.
Breeding distribution of
Rosy Starling in Bulgaria,
1893-2002

244 British Birds 96 • May 2003 • 242-246
Rosy Starlings in Bulgaria
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 occu-
pied since 1960 (Mountfort & Ferguson-Lees
1961).
Our observations, particularly at the
Karnobat quarry where Rosy Starlings have
bred in every year since 1994, except 1997-98,
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 con-
siderable 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 2002.
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
Konstantin Nyagolov
179. Stone quarry, Karnobat, Burgas region, Bulgaria, 1996: a breeding site of Rosy Starlings Sturnus roseus.
Table 1. Numbers of breeding Rosy Star lings
Sturnus roseus at three stone/rock quarries in
Burgas region, Bulgaria, 1994-2002. Counts
are of numbers of individuals, not pairs.
Year Karnobat Banevo Chernivrakh
1994 100 ? ?
1995 3,000 ? ?
1996 4,000 ? ?
1997 0 ? ?
1998 0 ? ?
1999 120 ? ?
2000 2,000 1,800 1,360
2001 500 1,100 1,300
2002 3,200 1,600 0

245British Birds 96 • May 2003 • 242-246
Rosy Starlings in 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 sur-
rounding 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-
180. Adult male Rosy Starling Sturnus roseus, Karnobat, Burgas region, Bulgaria, 1996.
Konstantin Nyagolov
181. Juvenile Rosy Starling Sturnus roseus, Karnobat, Burgas region, Bulgaria, 1996.
Konstantin Nyagolov

246 British Birds 96 • May 2003 • 242-246
Rosy Starlings in 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 Conser vation
Programme kindly provided the opportunity to carr y 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. 1961. Observations on
the birds of Bulgaria. Ibis 103: 443-471.
Munteanu, D. 1997. 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. 2000. Die Invasion des
Rosenstares in Bulgarien im Jahre 2000. Orn. Mitt.: 240-
244.
Nyagolov, K. 1996. A breeding colony of Rose-coloured
Starlings near Karnobat. Neophron 1: 12. (In Bulgarian)
Reiser, O. 1894. Materialien zu einer Ornis balcanica II,
Bulgarien. Wien.
182. Rosy Starlings Sturnus roseus, Karnobat, Burgas region, Bulgaria, 1996.
Konstantin Nyagolov
Konstantin Nyagolov, Lyubomir Profirov, Tanyo Michev, Milko Dimitrov
Burgas Wetlands Project, Bulgarian-Swiss Biodiversity Conservation Programme, PO Box 167,
Burgas 8000, Bulgaria