1. Introduction
In former times, the Little Tern Sterna albifrons was
a typical breeding bird of the natural Drava river in
Slovenia, Croatia and Hungary. Due to the con-
struction of dams, the braided river zone of the
Drava has nearly been destroyed. Thus the Little
Tern’s extinct as a breeding bird in the early 80’s s
from the Slovenian Drava ([tumberger 1981,
Schneider-Jacoby 1996). Today only the 50 km
long border section between Croatia and Hungary
downstream the Mura confluence offers appropriate
gravel and sand banks and feeding grounds (both
the river and its backwaters) for this European wide-
ly endangered species. Pictures of the dynamic land-
scape can be found in the overview of the state of
the biological and landscape diversity in Croatia
(Radovi} 2000). The area is part of the most threat-
ened ecosystem in Croatia, and in Hungary already
preserved as National Park Danube–Drava. The area
was part of the Iron Curtain and little had been
known about it until 1990 (Schneider-Jacoby
1996). Since the first observations of the Little Tern
have been made in the breeding period of 1992 in
the Hungarian part of the Drava near Vízvár
(Fenyösi et al. 1992), several records in the follow-
ing years are proof of a steady occurrence of this
bird in this area (Bécsy 1994, 1995, Fenyösi &
Horváth 1995, Radovi} 1996).
Subsequent investigations by the author resulted in
the discovery of two further breeding sites in this
area.
2. Method and Area
The records were made during the author’s thesis
work “Investigation of the landscape and hydro-mor-
phological structure of the Drava river between
Legrad and Ferdinandovac” in the years between
1994 and 1999 (e.g. Mohl & Schwarz 1997c,
1998a,b). Birds nesting on suitable gravel banks dur-
ing the breeding season were recorded in the area
between Legrad and Ferdinandovac (Figure 1 & 2). 
3. Results
3.1 Breeding
Two further breeding sites on the Drava were discov-
ered. The 10–15 pairs of the Little Tern were breed-
ing in three mixed colonies together with Common
Terns. 
– In July 1994, the author recorded between 30–35
pairs of Common Terns and 4 pairs of Little Terns in
the border stretch near Vízvár. At the same time
30–35 pairs of Common Terns were recorded near
Legrad.
– In July 1997, the author recorded 5 pairs of Little
Terns in the company of 40–45 pairs of Common
Terns on a gravel bank near the Croatian village of
35
Acrocephalus 22 (104-105): 35 – 39, 2001
The nesting of the Little Tern Sterna albifrons on the Drava River in
Croatia and Hungary
Gnezdenje male ~igre Sterna albifrons na reki Dravi na Hrva{kem in Mad`arskem
Arno Mohl
WWF Austria, Reitschulgasse 23, A-8010 Graz, e-mail: am@steiermark.wwf.at
Figure 1: The area of investigation and occurence of the
Little Tern Sterna albifrons – study area in the square
presented on satellite picture – Figure 2 (map credit: Mohl &
Schwarz)
Slika 1: Obmo~je raziskave in pojavljanja male ~igre Sterna
albifrons – izrez obmo~ja raziskave je predstavljen na
satelitskem posnetku na sliki 2 (priprava karte: Mohl &
Schwarz)
Repa{. At the same time, further observations of
several Little Terns together with Common Terns in
the border stretch near Legrad and Vízvár were made.
– In 1998, M. Zeugin (personal comm.) found 3
pairs of Little Terns in the company of Common
Terns in the border stretch near Vízvár.
– In June 1999, the author observed 5–8 Little Terns
in the braided river zone of the border stretch near
Legrad. A colony of Common Terns was also present
on a gravel bank.
3.2 Feeding habitat
The dynamic and diverse riverine landscape is impor-
tant for the survival of the Little Tern. Feeding habi-
tats are shallow water zones and branches of the
Drava River, but also oxbows with stagnant water and
reed beds. Adults fly six kilometres and more to
search for food in sites with clear water and plenty of
young fish. On July 17 1997, for example, one or two
Little Terns and few Common Terns were always
present at noontime in oxbow Djambina at the
Croatian-Hungarian border, approaching and leaving
the site over some 40 m high Repas forest (Schnei-
der-Jacoby in lit.).
4. Conclusions
The 50 km river section between Legrad and
Ferdinandovac is the best preserved section with
extended gravel and sand islands and banks on the
Drava River. It is therefore the most valuable area for
36
Kratki ~lanki / Short articles
Breeding pairs or individuals/
[t. gnezde~ih parov ali osebkov
Site / Kraj Sterna albifrons Sterna hirundo Year / Leto Source / Vir
Vízvár 2 indiv. / os. several indiv. / nekaj os. August / avgust 1992 L. Fenyösi,
Z. Horváth, J. Stix 
Vízvár 8 indiv. / os. - July / julij 1994 L. Bécsy 
Vízvár 4 pairs / pari 30-35 pairs / parov July / julij 1994 A. Mohl
Legrad - 30-35 pairs / parov July / julij 1994 A. Mohl
Vízvár 4 pairs / pari 32 pairs / parov July / julij 1995 L. Bécsy 
Vízvár 10–15 indiv. (adult & juv.)/ 100–120 indiv. (adult & juv.)/ August / avgust 1995 L. Fenyösi, 
os. (odrasli in mladi) os. (odrasli in mladi) Z. Horváth
? 5-6 pairs / parov 50 pairs / parov 1996 D. Radovi} 
Legrad several indiv. / nekaj os. several indiv. / nekaj os. July / julij 1997 A. Mohl
Repa{,  5 pairs / parov 40-45 pairs / parov July / julij 1997 A. Mohl
downwards
the bridge
Repa{, 2 pairs / para - July / julij 1997 M. Schneider-
upwards Jacoby
the bridge
Vízvár several indiv. / nekaj os. several indiv. / nekaj os. July / julij 1997 A. Mohl
Vízvár 3 pairs / pari 1998 M. Zeugin
Legrad 5-8 indiv. / os. several indiv. / nekaj os. June / junij 1999 A. Mohl
Table 1: Occurrence of the Little Tern Sterna albifrons and Common Tern Sterna hirundo on the Drava between Legrad and
Ferdinandovac
Tabela 1: Pojavljanje male ~igre Sterna albifrons in navadne ~igre Sterna hirundo na Dravi med Legradom in
Ferdinandovcem
37
A
cro
ceph
alus 22
(104-105): 35 – 39, 2001
Figure 2: Satellite picture of the Drava river with the planned Novo Virje dam (KFA 1000 satellite image sponsored by Dornier through Euronatur. Map credit: Mohl/Schwarz)
Slika 2: Satelitski posnetek reke Drave z na~rtovano zajezitvijo Novo Virje (satelitski posnetek KFA 1000 je sponzoriral Dornier prek Fondacije Euronatur; priprava karte: Mohl & Schwarz)
nearly the entire ensemble of the riverine pioneer bird
species: the Little Tern, the Common Tern Sterna
hirundo, the Little Ringed Plover Charadrius dubius
and the Common Sandpiper Actitis hypoleucos.
Especially the occurrence of the Little Tern, which is
currently one of the few in the entire Pannonian
basin, underlines the high ecological value and the
international importance of this area. Hungary has
already protected the habitat at the Drava along the
Croatian border as a National Park. Furthermore, the
Strategy and Action Plan for Landscape and
Biodiversity has adopted the protection of the natu-
ral river banks of Mura and Drava as a high priority
in Croatia (Radovi} 2000). 
Nevertheless, the fact is that all remaining colonies
of the Little Tern are faced with serious problems
(Mohl & Schwarz 1997c, 1998a,b, Schneider-
Jacoby 1994, 1996, 1998): 
1. The most important threat is habitat loss due to
alterations of the natural dynamic processes by the
ongoing river regulation activities, e.g. recently in the
specially protected area of the Mura confluence
“Veliki Pazut”. Further regulations have been planned.
2. Excavation of sand and gravel even from the
active colonies and destruction of breeding sites in
Croatian territory and at the border (e.g. between
Botovo and the specially protected area Veliki Pazut).
3. After the fall of the Iron Curtain, human distur-
bance of the colonies on the gravel and sand banks
(water sport tourism, anglers, swimmers) is an
increasing threat. 
4. The Croatian hydropower plant “Novo Virje”
(HEP 1997), which would have a negative impact on
the entire breeding area, is still planned and the
Environmental Assessment Study has been recently
approved by the responsible commission in Croatia
(pre-release 22.2.2001 of the Ministry of Environ-
ment and Spatial Planning “HE Novo Virje”). 
A middle- to long-term disappearance of the Little
Tern can be expected if the ongoing impact of the
water management in Croatia is not stopped and no
appropriate nature conservation efforts including
river restoration measures and visitor regulation are
carried out. The concept of a transboundary protect-
ed area (e.g. the proposed “Biosphere Reserve Drava-
Mura” (e.g. Euronature 1998, Schneider-Jacoby
1996, 1998) for the survival of the dynamic river land-
scape and the occurrence of the Little Tern in future
would be an important step. As the site is registered
as an IBA –Croatia 011, Hungary 007– (Heath &
Evans 2000) and the preservation is a priority in
Croatia and Hungary, the impact on the habitat and
the colonies of this European widely endangered
species (Tucker & Heath 1994) should be immedi-
ately stopped by the responsible authorities, e.g.
Ministry of Environment – HR and HU, State
Directorate for Water – HR. 
Summary
The article gives an overview of the last remaining
breeding sites of the Little Tern Sterna albifrons on
the Drava river in the border section between Legrad
and Ferdinandovac. These are the last breeding pop-
ulations that regularly occur in the Pannonian basin.
Due to habitat loss, only 10–15 pairs in three
colonies have survived on the gravel and sand banks
of the river. All pairs were found in mixed colonies
together with Common Terns Sterna hirundo. Their
survival on the Drava is very unsure. Particularly
habitat loss, caused by still ongoing river regulation
activities and human disturbance, is seriously threat-
ening the existence of this European highly endan-
gered species. 
Povzetek
^lanek obravnava zadnja {e obstoje~a gnezdi{~a male
~igre Sterna albifrons na reki Dravi v mejnem obmo-
~ju med Hrva{ko in Mad`arsko med Legradom in
Ferdinandovcem. Gre za zadnjo populacije ptic, ki
redno gnezdijo v Panonski ni`ini. Zaradi izgube
habitata je na prodnato–pe{~enih otokih Drave
pre`ivelo le 10 do 15 parov male ~igre v treh lo~enih
kolonijah. Vsi pari so bili odkriti v me{anih kolonijah,
in sicer skupaj z navadno ~igro Sterna hirundo.
Obstanek male ~igre na Dravi je nadvse negotov, saj
izguba habitata – kot posledica nezmanj{anega
reguliranja reke in drugih ~lovekov posegov – resno
ogro`a obstoj te v Evropi mo~no ogro`ene vrste.
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Arrived / Prispelo: 9.1.2001
Accepted / Sprejeto: 15.6.2001
39
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