211
Acrocephalus 32 (150/151): 211−212, 2012
Plastic fibres cause a brood 
failure in a Long-legged Buzzard 
Buteo rufinus nest
Plastična vlakna kot vzrok propada legla 
rjaste kanje Buteo rufinus
Boyan Milchev1 & Valeri Georgiev2
 1 University of Forestry; Wildlife Management 
Department, 10 Kl. Ochridski Blvd., BG–1765 Sofia, 
Bulgaria, e–mail: boyan.m@abv.bg
 2 Ministry of Environment and Water, 22 Maria Luisa 
Blvd., BG–1000 Sofia, Bulgaria,  
e–mail: nnpsf@moew.government.bg
The Long-legged Buzzard Buteo rufinus expanded its 
breeding range in SE and Central Europe in the second 
half of the 20th century (Munteanu et al. 1997, Mebs 
& Schmidt 2006). Its largest European population is 
found in Bulgaria with about 800–1,000 pairs and 
conservation status Vulnerable (Vatev et al. 2011). 
Nests on the rocks are preferred than on trees or power-
transmission towers in Bulgaria, and several pairs breed 
in quarries. Due to the generally greater burdening of 
the environment with plastic waste, the Long-legged 
Buzzard increasingly uses more artificial materials for 
nest lining (Milchev 2009), contrary to the former 
reports from Bulgaria (Vatev 1987, Simeonov et 
al. 1991). The nests in the quarries are always lined 
inside with plastic bags, fibre, string, and metal 
wire (Milchev 2009). The use of plastic materials 
by birds in the nest construction is an innovation, 
operationally defined as “a new or modified learned 
behaviour not previously found in the population” 
(Reader & Laland 2003). The plastic strings appear 
to be a new factor contributing to clutch losses and 
adult bird mortality usually owing to the entanglement 
of the nestling’s legs and rarely of the brooding bird 
(Montevecchi 1991, Ptaszyk 1994, Dolata 2006, 
Votier et al. 2011). In this study we report on a similar 
recorded case concerning this raptor.
A Long-legged Buzzard pair bred in the abandoned 
part of a stone quarry in the municipality Elhovo, SE 
Bulgaria, for the first time in 2010. The birds had two 
eggs and successfully reared two fledglings. The nest 
was inaccessible for predatory mammals and the pair 
used it again in the ensuing year. But in that year, the 
nest lining comprised multiple elastic plastic fibres 
partially intertwined with other nesting materials and 
twigs (Figure 1). An adult bird was seen sitting on the 
neighbouring rocks on 29 Apr 2011, but the brood 
with two eggs had apparently been abandoned. One 
of the eggs inside the nest had already been broken, 
the other covered by plastic fibres. They formed 
a kind of a net but were not flattened by the body 
of the incubating bird. The net had maintained its 
bulk structure, virtually encasing the eggs in it. This 
obviously hindered the incubation, the turning of the 
eggs, and movements of the brooding bird in the nest. 
We conclude that it was the net of plastic fibres that 
caused the brood abandonment.
The previous findings of plastic materials in the 
Long-legged Buzzard’s nest linings and pellets had not 
provided any proven negative impact on its breeding 
success (Milchev 2009). The same was established in 
the nests and pellets of the Egyptian Vulture Neophron 
percnopterus in SE Bulgaria (Miltschew & Georgiewa 
1994, Miltschew 1996, own data). However, these 
materials were made of softer plastic, which did 
not form elastic net structures. This first case of the 
abandoned Long-legged Buzzard brood caused by 
plastic fibres intertwined in nest lining should have been 
taken into account also in the conservation measures 
developed in respect to the Egyptian Vulture, which is 
an Endangered species (category EN) with about 60–
75 pairs in Bulgaria (Kurtev et al. 2011, IUCN 2011).
Povzetek
Največja evropska populacija rjaste kanje Buteo rufinus 
živi v Bolgariji, kjer najpogosteje gnezdi v skalnih 
Figure 1: An abandoned Long-legged Buzzard Buteo rufinus 
nest with net of plastic fibres as nest lining in a stone quarry, 
SE Bulgaria (photo: B. Milchev)
Slika 1: Opu{~eno gnezdo rjaste kanje Buteo rufinus 
z mrežo iz plasti~nih vlaken, ki so bila uporabljena kot 
gnezditveni material v kamnolomu, JV Bolgarija (foto: B. 
Milchev)
212
stenah, nekaj parov pa tudi v kamnolomih. Zaradi vse 
večjega obremenjevanja okolja s plastičnimi odpadki 
so pri vrsti v zadnjem času zabeležili porast uporabe 
plastičnih materialov pri graditvi gnezd. Uporaba le-
teh za gnezditveno gradivo je opredeljena kot inovacija 
oziroma novo naučeno vedenje, pred tem nepoznano 
v njeni populaciji. Dne 29.4.2011 je bila na gnezdišču 
v mestni občini Elhovo (JV Bolgarija), kjer je bilo 
gnezdenje para leta 2010 uspešno, opazovana odrasla 
ptica ob gnezdu z opuščenim leglom. Očiten vzrok 
za takšno stanje je bil preplet plastičnih vlaken, ki je 
oblikoval gosto in elastično mrežo ter prekrival jajci in 
s tem domnevno oviral valjenje oziroma obračanje jajc 
v gnezdu. Avtorja sta zaključila, da so plastična vlakna 
povzročila propad legla. Prejšnje najdbe plastičnih 
materialov v gnezdih rjastih kanj niso potrdile 
negativnega vpliva na gnezditveni uspeh. Podatek 
o propadu legla zaradi plastičnih vlaken bi morali 
upoštevati tudi pri načrtovanju varstvenih ukrepov za 
globalno ogroženega egiptovskega jastreba Neophron 
percnopterus.
References
Dolata, P. (2006): The White Stork Ciconia ciconia 
protection in Poland by tradition, customs, law, and 
active efforts. pp. 477–492 In: Tryjanowski, P., Sparks, 
T.H. & Jerzak, L. (eds.): The White Stork in Poland: 
studies in biology, ecology and conservation. – Bogucki 
Wydawnictwo Naukowe, Poznań.
IUCN (2011): The IUCN Red List of Threatened Species. 
Version 2011.1. – [www.iucnredlist.org], 15/11/2011.
Kurtev, M., Vatev, I. & Demerdjiev, D. (2011): Egyptian 
Vulture (Neophron percnopterus). In: Golemanski, V. 
(ed.): Red Data Book of Bulgaria. Vol. II. Animals. – 
Bulgarian Academy of Sciences, Sofia.
Mebs, T. & Schmidt, D. (2006): Die Greifvögel Europas, 
Nordafrikas und Vorderasiens. Biologie, Kennzeichen, 
Bestände. – Franckh-Kosmos Verlag, Stuttgart.
Milchev, B. (2009): Breeding biology of the Long-legged 
Buzzard Buteo rufinus in SE Bulgaria, nesting also in 
quarries. – Avocetta 33: 25–32.
Miltschew, B. (1996): Wiederherstellung eines Horstes 
des Schmutzgeiers. – Ornithologische Mitteilungen 48: 
124–126. 
Miltschew, B. & Georgiewa, U. (1994): Verbreitung, 
Fortpflanzungsverhalten und Ernährung des 
Schmutzgeiers (Neophron percnopterus (L.)) im 
Strandsha-Gebirge. – Ecologia (BAS, Sofia) 26: 68–77.
Montevecchi, W. (1991): Incidence and types of plastic 
in gannets’ nests in the Northwest Atlantic. – Canadian 
Journal of Zoology 69: 295–297.
Munteanu, D., Todorov, R. & Vatev, I. (1997): Long-
legged Buzzard Buteo rufinus. pp. 159 In: Hagemeijer, 
W.J.M. & Blair, M.J. (eds.): The EBCC Atlas of 
European breeding birds: Their distribution and 
abundance. – T & AD Poyser, London.
Ptaszyk, J. (1994): Binfäden aus Polypropylen als Ursache 
des Todes junger Weißstörche (Ciconia ciconia) und 
anderer Tiere. – Pr. Zakł. Biol. Ekol. Ptaków UAM 3: 
177–181. 
Reader, S. & Laland, K. (eds.) (2003): Animal Innovation. 
– Oxford University Press, Oxford.
Simeonov, S., Michev, T. & Nankinov, D. (1991): [Fauna 
Bulgarica. Vol. 20. Aves. Part I.] – BAS, Sofia. (in 
Bulgarian)
Vatev, I. (1987): Notes on the breeding biology of the Long-
legged Buzzard (Buteo rufinus) in Bulgaria. – Journal of 
Raptor Research 21: 8–13. 
Vatev, I., Angelov, I., Domuschiev, D., & Profirov, 
L. (2011): Long-legged Buzzard (Buteo rufinus). In: 
Golemanski, V. (ed.): Red Data Book of Bulgaria. Vol. 
II. Animals. – Bulgarian Academy of Sciences, Sofia.
Votier, S., Archibald, K., Morgan, G. & Morgan, L. 
(2011): The use of plastic debris as nesting material by a 
colonial seabird and associated entanglement mortality. – 
Marine Pollution Bulletin 62: 168–172.
Arrived / Prispelo: 15. 11. 2011
Accepted / Sprejeto: 23. 9. 2012
B. Milchev & V. Georgiev: Plastic fibres cause a brood failure in a Long-legged Buzzard Buteo rufinus nest