9
Acrocephalus 22 (104-105): 9 – 21, 2001
Status of tubenose seabirds Procellariiformes breeding in the
eastern Adriatic
Status cevonoscev Procellariiformes, gnezde~ih v Jadranskem morju
Mauricio Stip~evi}1 & Gordan Luka~2
1Josipa Relje Vladovi}a 29, HR-23000 Zadar, Croatia
2National Park Paklenica, HR-23244 Starigrad-Paklenica, Croatia
Three species of the seabird order Procellariiformes are regular in the Adriatic:
Cory’s Shearwater Calonectris diomedea, Yelkouan Shearwater Puffinus yelk-
ouan and Storm Petrel Hydrobates pelagicus. They have all been considered
breeders on some offshore Croatian islands. The breeding of Cory’s
Shearwater Calonectris diomedea was confirmed for the first time in June 1984
on Svetac Island when three adults and one egg were found. On the west
slope of the island two occupied nest holes with one egg in each were found
in July 1998, while in June 1999 a brooding adult and an egg in nest hole
were discovered. Five occupied nest holes of Cory’s Shearwater were found
on the island of Palagru`a in August and September 1997, from which three
nestlings and two adult birds were extracted. We estimate that at least 20
pairs breed on this particular island. The plumage development of fledglings
from Palagru`a indicates the start of egg laying between April and May and
departure of full-grown juveniles between September and October. The pres-
ence of Cory’s Shearwater is more confined to the southern Adriatic. The
breeding of Yelkouan Shearwater Puffinus yelkouan on the island of Svetac
presumed on the basis of two females found in crevices by fishermen in 1962.
From summer to autumn, rafts of 500 to 1,000 Yelkouan Shearwaters regu-
larly move along the eastern Adriatic and concentrate in the Gulf of Kvarner
(June), in the Gulf of Trieste (September) and in northern Dalmatia
(October). The concentration of Yelkouan Shearwaters in the top corner of
the Adriatic takes place in the areas of the eastern Adriatic with strong input
of freshwater that attracts huge shoals of small pelagic fish. The summer/
autumn distribution of Yelkouan Shearwater reveals the importance of the
highly productive northern Adriatic as a foraging and post-breeding moult-
ing area for birds from the Adriatic colonies and other parts of the
Mediterranean. Storm Petrel Hydrobates pelagicus was found between June
and November along the eastern Adriatic and has been claimed to breed on
the islet of Jabuka on the basis of a single observation. 
Key words: Calonectris diomedea, Cory’s Shearwater, Puffinus yelkouan, Yelkouan
Shearwater, Hydrobates pelagicus, Storm Petrel, status, eastern Adriatic
Klju~ne besede: Calonectris diomedea, rumenokljuni viharnik, Puffinus yelkouan,
sredozemski viharnik, Hydrobates pelagicus, strako{, status, vzhodni Jadran
1. Introduction
Among the 9 species of tubenosed seabirds recorded
in the Adriatic (Frugis et al. 1993), three breed on
Adriatic islands. In the eastern Adriatic Croatian
waters only Cory’s Shearwater Calonectris diomedea,
Yelkouan Shearwater Puffinus yelkouan (former east
Mediterranean race “Levantine” Shearwater Puffinus
puffinus yelkouan, e.g. Bourne et al. 1988, Harrison
1989, Walker et al. 1990, Hazevoet 1995, Heidrich
et al. 1998, Mayol 1998) and Storm Petrel Hydrobates
pelagicus have been recorded (Kralj 1997, Luka~
1998). They are all supposed to breed on Dalmatian
offshore islands (Cramp et al. 1977, Kralj 1997,
Luka~ 1998) but there is still no adequate confirma-
tion as to their breeding (e.g. breeding colonies, eggs,
nestlings). The Croatian population’s status is
unknown, and some other aspects of their biology
have not been studied as yet. Breeding is merely pre-
sumed (Massa & Lo Valvo 1986, Akriotis &
Handrinos 1986) or established on the basis of the
observations by Krpan (1965, 1970, 1977 & 1980). The
main source of evidence as far as breeding is con-
cerned are local fishermen who have been tradition-
ally hunting Cory’s and Yelkouan Shearwaters on sev-
eral islands for food. The size of the Croatian Cory’s
Shearwater’s population has been estimated by
Tucker & Heath 1994 and Luka~ 1998, and the
Yelkouan Shearwater’s population by Luka~ 1998.
The pattern of seasonal migration or feeding move-
ments inside the Adriatic has not been ascertained as
yet. Some observations of Cory’s Shearwaters and the
occurrence of Yelkouan Shearwater rafts in the north-
ern Adriatic (Bernhauer 1957, Rucner 1957, [tro-
mar 1975, Gjerke{ 1986, Bo`i~ 1994, Tome 1986,
Rubini~ 1996, Sovinc 1997) indicate regular move-
ments along the eastern Adriatic.
The recent data has been gathered since 1983 dur-
ing the ornithological investigations in the Croatian
Adriatic. In the paper some new information on the
status of all three tubenose seabirds breeding in the
Adriatic, including breeding distribution, population
estimates and seasonal occurrences, is presented. We
reviewed the so far existing historical information as
well as the new data collected during recent field
work carried out in the Adriatic to get a better insight
into the status and distribution of these seabirds in
the eastern Adriatic.
2. Study area and methods
2.1. Study area
The study area covers the entire eastern Adriatic
region from the Gulf of Trieste (including the north-
eastern Italian coastline and the narrow coastline of
Slovenia) to the coast of Montenegro, the greater part
of which lies within the territory of Croatia. The
Adriatic Sea, 783 km long and from 102 to 355 km
wide, is in fact a gulf of the Mediterranean Sea
between the Balkans and Apennine peninsula. The
eastern Adriatic coast is mainly rocky, steep and one
of the most indented in the Mediterranean. There are
more than 700 scattered islands and islets along the
eastern Adriatic, from the mouth of the So~a river in
Italy down to the mouth of the Bojana river in
Montenegro (Pomorska Enciklopedija 1976).
Almost all islands are Croatian and the greatest num-
ber of them lie along the eastern Adriatic close to the
mainland (“coastal islands”). The group of the
remotest Croatian islands (“offshore islands”) in the
central Adriatic region is the breeding area for regular
Adriatic tubenose seabirds. Several uninhabited off-
shore islands and islets (Bi{evo, Sv. Andrija, Kamik,
10
M. Stip~evi} & G. Luka~: Status of tubenose seabirds Procellariiformes breeding in the eastern Adriatic
Table 1: Principal division of the Adriatic Sea basin in view of its main physical, chemical and biological features (BENOVI] 1983)
Tabela 1: Osnovna razdelitev jadranskega bazena glede na njegove glavne fizi~ne, kemijske in biolo{ke zna~ilnosti (BENOVI] 1983)
North Adriatic Northern Adriatic region
Gulf of Trieste, W Istra, Kvarner Smaller depth (below 50m); Greater variation of temperature; Lower
salinity; Lower biodiversity; Greatest biological production; Pelagic fish
community – fewer species but greater biomass; Fishing industry well 
developed
South Adriatic Central Adriatic region Southern Adriatic region
Dalmatia, offshore islands Greater depth (100–200m); Lower Greatest depth (200–1,300m);
variation of temperature; Greater Lowest variation of temperature;
salinity; Greater biodiversity; Lower Greatest salinity; Greatest
biological production; Best fishing area biodiversity; Lowest biological
around offshore islands (Jabu~ka production; Fishing industry
Kotlina) scarcely developed
Brusnik, Jabuka, Su{ac, Palagru`a) are very suitable
for the breeding tubenose birds. Some other islands
and islets in the central Adriatic between the offshore
islands and the mainland (Vis, Kor~ula, Lastovo) are
often quoted as the breeding ground of tubenose
seabirds (Krpan 1965, 1970, 1977, 1980), although
there is still no clear evidence of these birds breeding
there. Cory’s and Yelkouan Shearwaters also breed on
some Italian islets in the western Adriatic (Cramp &
Simmons 1977). For data presentation, the Adriatic
Sea basin was divided into the northern and southern
Adriatic (Table 1) according to the main physical,
chemical and biological features of the northern, cen-
tral and southern regions of the Adriatic (e.g. Beno-
vi} 1983). For more detailed division of the study
area see Figure 1. 
2.2. Methods
All main parts of the Croatian inshore and offshore
waters were surveyed in all seasons. Regular observa-
tions were also performed on the open sea from
numerous boat trips, cruises and ferryboats. New data
have been collected recently on the group of central
Adriatic offshore islands where all three species are
presumed to breed. We visited this group of remote
Croatian islands on several occasions from 1996 to
1999, i.e. in March and the June–October period.
Other sources of information were various published
papers and several bird collections kept by the Croatian
Natural History Museum Zagreb (CNHM), Natural
History Museum Split (NHMS), Institute of
Ornithology Zagreb (IO), Institute of Biology
11
Acrocephalus 22 (104-105): 9 – 21, 2001
Figure 1: Main regions of the Adriatic Sea: 1a – Northern (N), Central (C), Southern (S) Adriatic regions; 1b – Northern
Adriatic: Gulf of Trieste (A), W Istra (B), Kvarner (C); Southern Adriatic: Dalmatia (D); offshore islands (E): 1c – 1. Vis 2. Bi{evo
3. Sv. Andrija (Svetac) 4. Kamik 5. Brusnik 6. Jabuka 7. Su{ac 8. Palagru`a
Slika 1: Glavna obmo~ja Jadranskega morja: 1a – severno (N), srednje (C) in ju`no (S) obmo~je; 1b – severni Jadran: Tr`a{ki
zaliv (A), zahodna Istra (B), Kvarner (C); ju`ni Jadran: Dalmacija (D); oddaljeni otoki (E): 1c – 1. Vis 2. Bi{evo 3. Sv. Andrija
(Svetac) 4. Kamik 5. Brusnik 6. Jabuka 7. Su{ac 8. Palagru`a
Dubrovnik (BID), and Museo Civico di Storia
Naturale Trieste (MCSNT). 
3. Results 
Cory’s Shearwater
In June 1984, two bird-ringers extracted, with the aid
of local fishermen, three brooding adults and a single
egg from nest holes on the southern part of Svetac
Island. The adult birds were ringed (Klete~ki 1988,
IO). In July 1998, two active nest holes, including
one egg, were found in the crevices with soft soil on
the island’s steep western slope (V.[. & V.D.). In June
1999, we found an egg and a brooding bird in an
occupied nest hole under a rock on the island’s west-
ern slope (Figures 2a-c).
12
M. Stip~evi} & G. Luka~: Status of tubenose seabirds Procellariiformes breeding in the eastern Adriatic
Table 2: Monthly number of fieldwork days in the northern and southern Adriatic and total number of records of Cory's and
Yelkouan Shearwaters along the eastern Adriatic coast from 1985–1998 (number of days on which authors observed
particular tubenose seabirds)
Tabela 2: [tevilo terenskih dni v mesecu v severnem in ju`nem Jadranu in celotno {tevilo opa`anj rumenokljunega in
sredozemskega viharnika vzdol` ju`ne obale Jadranskega morja med letoma 1985 in 1998 ({tevilo dni, v katerih sta avtorja
opazovala dolo~ene vrste cevonoscev)
1985-1998 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Total
North Adriatic 26 3 23 38 43 27 21 32 16 15 9 6 259
Calonectris diomedea 1 1
Puffinus yelkouan 2 1 2 1 6
South Adriatic 112 52 91 87 85 62 64 96 85 91 65 92 982
Calonectris diomedea 7 6 6 7 26
Puffinus yelkouan 4 5 5 2 8 2 26
Total 138 55 114 125 128 89 85 128 101 106 74 98 1241
Figure 2a: Svetac Island, NE slope, 11. June 1999 
(photo: K. Leskovar)
Slika 2a: Otok Svetac, SV pobo~je, 11.6.1999 
(foto: K. Leskovar)
Figure 2b: Western slope of Svetac Island on which the
nest hole was found, 11. June 1999 (photo: K. Leskovar)
Slika 2b: Zahodno pobo~je otoka Svetac, na katerem je bil
najden gnezdilni rov, 11.6.1999 (foto: K. Leskovar)
On the remotest Croatian offshore island of Pala-
gru`a, five occupied nest holes were found in 1997.
The first active nest hole was found beneath a rock
on 22nd August in the inlet of Stara Vlaka. The
length of the hole was about 70 cm with a sharp right
curvature. During the evening, both adults visited the
hole from which a nestling responded with calls.
During the evening at least 6 more calls were heard
from the surrounding rocks in the inlet. On 28/29th
August two adults were caught and ringed at the pre-
viously discovered nest hole. Their wing length (354
mm, 328 mm) suggested a male and female C. d.
diomedea. From 18th to 21st September, the ringers
found another two nest holes and eventually three
fledglings were extracted from the three nest holes.
Another two occupied nest holes were found on the
following few days. Altogether, five nest holes were
13
Acrocephalus 22 (104-105): 9 – 21, 2001
Figure 2c: Brooding Cory's Shearwater Calonectris
diomedea in a nest hole under a rock on the western slope
of Svetac Island, 11. June 1999 (photo: K. Leskovar)
Slika 2c: Vale~i rumenokljuni viharnik Calonectris diomedea
v gnezdilnem rovu pod skalo na zahodnem pobo~ju otoka
Svetac, 11.6.1999 (foto: K. Leskovar)
Figure 3 a-c: Maximum daily number of observed
individuals of Cory's Shearwater Calonectris diomedea per
months along the eastern Adriatic (a – northern Adriatic, b –
Dalmatia, c – offshore islands). The data are combined from
the authors' fieldwork, data published from 1876 on, and
from other sources. 
Slika 3 a-c: Maksimalno dnevno {tevilo opazovanih
rumenokljunih viharnikov Calonectris diomedea v posameznih
mesecih vzdol` vzhodne obale Jadranskega morja (a –
severni jadran, b – Dalmacija, c – oddaljeni otoki). Podatki so
kombinacija terenskega dela obeh avtorjev, podatkov,
objavljenih od leta 1876 dalje, in drugih virov.
found in 1997 in crevices with soft soil at the foot of
steep cliffs and in burrows beneath rocks.
The seasonal distribution of observations (Figures 3
& 4) shows a regular presence of dispersed birds or
smaller rafts in the southern Adriatic, on the open sea
around offshore islands and along the group of the great
Dalmatian coastal islands (Bra~, Hvar, Mljet, Kor~ula,
Lastovo). Greater rafts of up to 100 birds appeared
from June to September mainly in the southern
Adriatic between Dalmatian offshore and inshore
islands. An exceptionally huge raft of 2,000 birds
assembled about 2 hours before the sunset off the island
of Svetac in July 1998 (V.[. & V.D.) In the northern
Adriatic, a small number of Cory’s Shearwater was
recorded from May to October, including a raft of
30–40 birds in Kvarner in August 1912 (Schiebl 1914).
14
M. Stip~evi} & G. Luka~: Status of tubenose seabirds Procellariiformes breeding in the eastern Adriatic
Figure 4: Distribution of the Cory's Shearwater Calonectris diomedea records (combined data published from 1876 on and the
authors' data) along the eastern Adriatic coast. The key for the four symbol sizes from the smallest to the largest circle is 1–10,
11–100, 101–500, 2,000 birds. 
Slika 4: Opa`anja rumenokljunega viharnika Calonectris diomedea (kombinacija podatkov, objavljenih od leta 1876 dalje, in
podatkov avtorjev pri~ujo~ega ~lanka) vzdol` vzhodne jadranske obale. Posamezni krogi ponazarjajo skupine po 1–10, 11–100,
101–500 in 2.000 ptic.
There are only a few records from October to April
along the offshore islands in Dalmatia and Kvarner.
Yelkouan Shearwater 
The seasonal distribution of observations (Figs. 4 &
5) reveals regular presence of the Yelkouan Shearwater
in the southern and northern Adriatic from April to
December. Rafts of various sizes were seen mostly
along the offshore islands in Dalmatia, in Kvarner,
along the west coast of Istra and in the Gulf of
Trieste. Notable concentrations of rafts were recorded
in summer and autumn between the offshore islands
in the southern Adriatic (presumed breeding islands)
and in the Gulf of Trieste in the northern Adriatic.
The most remarkable were rafts numbering from few
hundred to 1,000 birds (Gjerke{ 1986) seen from
15
Acrocephalus 22 (104-105): 9 – 21, 2001
Figure 5: Distribution of the Yelkouan Shearwater Puffinus yelkouan records (combined published data from 1888 and the
authors' data) along the eastern Adriatic coast. (The key for the four symbol sizes from the smallest to the largest circle is
1–10, 11–100, 101–500, 501–1,000 birds).
Slika 5: Opa`anja sredozemskega viharnika Puffinus yelkouan (kombinacija podatkov, objavljenih od leta 1888 dalje, in
podatkov avtorjev pri~ujo~ega ~lanka) vzdol` vzhodne jadranske obale (posamezni krogi ponazarjajo skupine po 1–10, 11–100,
101–500 in 501–1.000 ptic).
June to October in the Gulf of Trieste, in Kvarner
and in northern Dalmatia. In April and in the
November–December period only few birds were
observed along the eastern Adriatic.
Storm Petrel 
There are only few published records on the Storm
Petrel along the entire eastern Adriatic, all from June
to November in Croatian waters. The first record was
the specimen collected in August 1895, from the
inshore Dalmatian island of Hvar (Rössler 1902,
MCSNT). The most important record indicating
possible breeding were several smaller groups or sin-
gletons seen in June 1962 around the offshore vol-
canic islet of Jabuka (Krpan 1965). Other records
were the specimens collected all over Dalmatia
(CNHM, BID), except one from western Istra
(MCSNT). In the afternoon of 30th July 1998 a sin-
gle bird alighted on an outcrop offshore the islet of
Kamik (V.[. & V.D.). 
4. Discussion
Cory’s Shearwater
According to Krpan (1965), the Cory’s Shearwater
breeds on Dalmatian offshore islands and islets
around the islands of Vis as well as on Bi{evo, Sv.
Andrija (Svetac), Jabuka and Kamik. Reports on the
bird’s breeding have come from other islands as well,
including Vis, Palagru`a, Su{ac, Kopi{te (Lastovo)
(Krpan 1970, Kralj 1997), but have not been con-
firmed until recently on the two offshore islands of
Svetac and Palagru`a.
Size and distribution of colonies are unknown, but
rafts observed near the presumed breeding grounds
on offshore islands indicate a few hundred pairs at
least. On the island of Palagru`a, three nestlings and
two adults were extracted from five nest holes in
September 1997. Considering that the search was not
particularly successful we presume that many pairs
breed on the island of Palagru`a especially on inac-
cessible cliffs. For the entire island we estimated the
size of the colony at 20 pairs at least. On the offshore
island of Svetac, two active nest holes with one egg in
each were found in July 1998, while in June 1999 a
brooding adult with one egg in a single nest hole was
discovered. However, the huge raft of 2,000 birds
observed at sunset off the island of Svetac indicates
greater size of the breeding population on the
Croatian offshore islands. The size of Croatian breed-
ing population was estimated at 1,000–5,000 pairs
(Tucker & Heath 1994). Although such population
size was not confirmed with a reliable colony census
16
M. Stip~evi} & G. Luka~: Status of tubenose seabirds Procellariiformes breeding in the eastern Adriatic
Figure 6 a-c: Maximum daily number of the observed
Yelkouan Shearwater Puffinus yelkouan individuals per
months along the eastern Adriatic (a – northern Adriatic, b –
Dalmatia, c – offshore islands). The data are combined from
the authors' fieldwork, the data published from 1876, and
from other sources. 
Slika 6 a-c: Maksimalno dnevno {tevilo opazovanih
sredozemskih viharnikov Puffinus yelkouan v posameznih
mesecih vzdol` vzhodne obale Jadranskega morja (a –
severni jadran, b – Dalmacija, c – oddaljeni otoki). Podatki
so kombinacija terenskega dela obeh avtorjev, podatkov,
obljavljenih of leta 1876 dalje, in drugih virov.
or supported with appropriate counting data, it
should be a realistic figure in view of the raft of 2,000
birds assembling off the island of Svetac in July 1998.
In general, the breeding cycle of the Palagru`a birds
is in accordance with the data of Del Hoyo et al.
(1992), Cramp et al. (1977) and Massa & Lo Valvo
(1986). The plumage development of the ringed
fledglings indicates commencement of egg laying
around April/May and departure of full-grown juve-
niles from nesting colonies during the September–
October period.
Movements 
In the Adriatic, the Cory’s Shearwater is more con-
fined to the southern Adriatic as revealed by the gath-
ered data. In the breeding season they occur off
Dalmatia from May to September, around the off-
shore islands and great inshore islands, usually in
small numbers or rafts reaching up to one hundred
birds. Less often they have been encountered in the
northern Adriatic. A small number of birds appear-
ing in January and from May to November in
Kvarner indicates movements along the eastern
Adriatic.
The rare observations in the winter period indicate
migratory habit of the Adriatic birds. In the winter,
the Mediterranean Cory’s Shearwater flies out into
the Atlantic, occurring from November to May off
South Africa (Cramp et al. 1977, Del Hoyo et al.
1992). The departure from the Mediterranean takes
place between mid-October and mid-November and
the return from mid-February to late March
(Telleria 1980 & 1981, Finlayson 1992). Scarce win-
ter records in the Adriatic thus fits well with the
migration scheme of the Mediterranean birds. The
January records from Kvarner and offshore islands
reveal that during the winter some birds remain in
the Adriatic. 
Yelkouan Shearwater
Breeding of Yelkouan Shearwaters was claimed on the
offshore islands of Vis, Bi{evo, Sv. Andrija, Jabuka,
Palagru`a and on the surrounding islets (Krpan
1965). Findings are based on two females extracted by
fishermen from nest holes on the offshore island of
Svetac in April 1962 (Krpan 1965), but breeding was
not confirmed on other islands. The precise breeding
distribution and colony size are still unknown. Due
to the common occurrence in the north Adriatic,
some authors wrongly reported on Yelkouan
Shearwater’s breeding in Kvarner (Lovri} 1971,
Makovec 1995, Rucner 1998). Indeed, the concen-
tration of rafts in the top corner of the Adriatic result-
ed from the movements inside the Adriatic. Such
trophic link between the northern and southern
Adriatic enables Yelkouan Shearwaters to exploit the
rich feeding zone in the northern Adriatic. The rafts
observed during the breeding seasons around the off-
shore Dalmatian islands indicate a few hundred
breeding pairs. This estimate is in accordance with
the population of several hundred pairs presumed to
breed off Croatia (Luka~ 1998). We can presume that
birds from other Mediterranean colonies enter the
landlocked Adriatic for feeding. Most probably, a
proportion of birds engaged in summer/autumn feed-
ing movements between the offshore islands and the
Gulf of Trieste are non-breeders visiting the Adriatic
from unknown parts of the Mediterranean (Yésou in
lit.).
Movements
Summer/autumn movements of Yelkouan Shearwa-
ters along the eastern Adriatic reflect a general pat-
tern of the feeding ecology of marine birds well
adapted to highly pelagic lifestyle. From spring to
autumn, lower salinity and inflow of nutrients
through the river Po and other tributaries (especially
after snow melts in the Alps) increase the primary
production of the northern Adriatic, attracting huge
shoals of small pelagic fish (Sardines Clupea
pilchardus, Sprats Sprattus sprattus, Anchovies
Engraulius encrasicolius). After wintering in deep off-
shore waters, shoals of small pelagic fish shift towards
the shallow and nutrient rich north Adriatic to
exploit summer planktonic blooms (Grubi{i} 1967,
Mili{i} 1994, Jardas 1996). Seasonal occurrence of
favourite fish prey attracted rafts of Yelkouan
Shearwater in the area between the presumed breed-
ing offshore islands in the southern Adriatic and in
the northern Adriatic where abundance of pelagic fish
shoals offer best fishing area in the entire Adriatic.
The summer/autumn occurrence of Yelkouan
Shearwaters along northern Dalmatia, Kvarner, west
Istra and the Gulf of Trieste followed the main con-
centrations of pelagic fish stocks in the Adriatic Sea.
Notable concentration of pelagic fish stocks were
found around great inshore islands, in channels and
bays of northern Dalmatia, Kvarner and the Gulf of
Trieste, largely in areas with strong input of freshwa-
ter (Grubi{i} 1967, Mili{i} 1994, Jardas 1996). The
Yelkouan Shearwater was also common on the Italian
side of the Gulf of Trieste (Perco et al. 1983).
The post-breeding movements by Yelkouan
Shearwaters are not well known (Cramp et al. 1977).
After breeding, Yelkouan Shearwaters disperse widely
in a nomadic and haphazard fashion, following their
17
Acrocephalus 22 (104-105): 9 – 21, 2001
main food source – huge shoals of Anchovies and
Sardines, not leaving Mediterranean in winter
(Cramp et al. 1977, Brooke 1990). Nomadism is an
adaptive response of seabirds to the wast areas within
which they must seek local concentration of food
(Nelson 1980). A post-breeding moult of congeneric
Balearic Shearwater Puffinus mauretanicus occurs at
the nearest most productive area with a huge concen-
tration of pelagic fish shoals (Cramp et al. 1977,
Yésou 1986, Brooke 1990). Mediterranean Shear-
waters, as Balearic Puffinus mauretanicus, that only
undertake a restricted migration, moult immediately
after breeding (Brooke 1990). The summer/autumn
distribution of Yelkouan Shearwater strongly indi-
cates the role of the productive northern Adriatic as
foraging and post-breeding moulting area for the
Adriatic birds and probably for some birds from other
parts of Mediterranean. The seasonal occurrence in
the northern Adriatic seems to be identical with peak
occurrence in extreme western Mediterranean from
July to October (Garcia 1973, Cortes et al. 1980,
Telleria 1981, de Juana & Paterson 1986), where
many moult from August to September (Harrison
1989). Although quoted in large numbers in the
extreme western Mediterranean many years ago, such
numbers no longer occur there (Paterson 1997,
Yésou in lit.).
Winter scarcity of Yelkouan Shearwaters in the
Adriatic is also similar to the winter absence in the
extreme western Mediterranean (Cortes et al. 1980).
Scarce records of a few birds in November to
December scattering over the inshore northern and
southern Adriatic confirmed their winter presence in
the Adriatic. Seasonal distribution of records suggests
migratory habit of the Adriatic birds in the winter.
Data for the winter occurrence indicate winter move-
ments of Yelkouan Shearwaters in the areas around
warmer southern Mediterranean along the North
African coast or in the Black Sea (Van Impe 1975,
Cramp et al. 1977, Jacob 1979, Del Hoyo et al.
1992). Along the north African coast it was found to
be common from October to February in Algeria
(Jacob 1979), regular in varying numbers off Libya
from December to March (Bundy 1950), and was
reported as numerous off Tunisian coast in winter
(Heim de Balsac & Mayaud 1962). In the Black Sea,
large flocks congregated near the eastern shore of
Crimea from October to December (Cramp et al.
1977).
Storm Petrel 
The first record was the specimen collected in August
1895 from the inshore Dalmatian island of Hvar
(Rossler 1902, MCSNT). Other records were the
collected specimens scattered over Dalmatia (CNHM,
BID), except one along west Istra (MCSNT). The
breeding of Storm Petrel was reported along
Dalmatian coast (Cramp et al. 1977) on account of
Krpan (1965). In June 1962 he observed, around the
small offshore volcanic islet of Jabuka, several small
groups or singletons, including a “young bird trying
to take off from the surface but incapable for a longer
flight”. Published data suggested only a scarce pres-
ence of the Storm Petrel in the eastern Adriatic from
June to November. As there is still not enough infor-
mation on the occurrence of this bird in the eastern
Adriatic, any statement on its status is unrealistic.
Acknowledgements: Our appreciation goes to Mr.
Pierre Yésou (Office National de la Chasse, Nantes)
for many suggestions.  We gratefully acknowledge
Mrs. Natalija Kajmak for correcting the English ver-
sion of the manuscript and Mr. Boris Kajmak
(Mozart Graphic) for figure adaptation. We also
thank the staff of the Institute of Ornithology in
Zagreb for enabling us an access to the archives of the
Croatian ringing centre, the Croatian Natural
History Museum in Zagreb for logistic support dur-
ing the sea-watch fieldwork, and to Mr. Ivo Bratovi}
who so many times organised pleasant sea cruises
along the Croatian coast. For field data we are
indebted to Vlatka [~etari} (V.[.) & Vlatka
Dumbovi} (V.D.) from Zagreb, and to Mr. Moller-
Pillot from the Netherlands. We are also thankful to
Kre{imir Leskovar from Zagreb for photographs from
the island of Svetac.
5. Conclusion
Three tubenose seabirds regularly present off the
eastern Adriatic have been claimed to breed on the
remotest Croatian offshore island. 
Cory’s Shearwater Calonectris diomedea breeding has
been recently confirmed on the two offshore islands
of Svetac and Palagru`a. The first evidence were
three brooding adults and with a single egg each
extracted by ringers from nest holes on the island of
Svetac in June 1984. On the western slope of the
same island, two nest holes with one egg in each
were found in July 1998, and in June 1999 a nest
hole with a brooding adult and an egg was discov-
ered. On Palagru`a, five occupied nest holes were
found between August and September 1997, from
which three nestlings and two adults were extracted.
The size of the colony on the island of Palagru`a is
estimated at 20 pairs at least. The rafts observed near
18
M. Stip~evi} & G. Luka~: Status of tubenose seabirds Procellariiformes breeding in the eastern Adriatic
the presumed breeding grounds on offshore islands
indicate a range from few hundred to few thousand
breeding pairs on Croatian islands. 
The plumage development of ringed fledglings
indicates the commencement of egg laying between
April and May, and departure of full-grown juveniles
from nesting colonies in Adriatic between September
and October. The scarce winter records indicate that
some birds remain in the Adriatic Sea during the win-
ter, but it seems that majority of them have the same
migratory habit as the Mediterranean population. The
occurrence of Cory’s Shearwaters is confined more to
the southern Adriatic than to the northern Adriatic.
Yelkouan Shearwater Puffinus yelkouan has been
claimed to breed on some offshore Croatian islands,
but the only evidence has been the report on two
females found in nest holes on the island of Svetac.
Rafts of 500 to 1,000 birds regularly moving along
the eastern Adriatic indicate size of several hundred
breeding pairs in the Adriatic Sea. Some of the birds
occurring in the Adriatic might be non-breeders or
breeders visiting the Adriatic from unknown parts of
the Mediterranean.
Summer and autumn concentrations of favourite
pelagic fish prey in the northern Adriatic attract rafts
of Yelkouan Shearwaters from their breeding grounds
on offshore islands in the southern Adriatic to forage
in the top corner of the Adriatic Sea. From spring to
autumn, the primary production of the northern
Adriatic increases and plankton growth enables a
huge shoals of pelagic fish to concentrate in the top
corner of the Adriatic, mainly around the areas with
strong input of freshwater. Along the eastern Adriatic,
the largest rafts from 500 to 1,000 birds were found
to concentrate in the Gulf of Kvarner (June), the Gulf
of Trieste (September) and in northern Dalmatia
(October). The summer/autumn distribution of
Yelkouan Shearwater indicates the role of productive
top corner of the northern Adriatic as foraging and
moulting area for the birds from the Adriatic and
probably from other parts of the Mediterranean as
well. The seasonal distribution of records suggests a
migratory habit in the majority of the Adriatic birds
in winter. 
Storm Petrel Hydrobates pelagicus was found in the
eastern Adriatic on several occasions from June to
November. Although claimed to breed on the islet of
Jabuka on the account of a single observation, there
is still no adequate evidence of its breeding.
6. Povzetek
Na oddaljenih otokih v hrva{kem Jadranu naj bi
redno gnezdile tri razli~ne vrste cevono`cev.
Gnezdenje rumenokljunega viharnika Calonectris
diomedea je bilo pred kratkim potrjeno na dveh
oddaljenih otokih v Jadranu, in sicer na Svetcu in
Palagru`i. Prvi dokaz o tem so bili trije vale~i osebki s
po enim jajcem, ki so jih obro~karji potegnili iz
gnezdilnih rovov na otoku Svetac junija 1984. Na
zahodnem pobo~ju istega otoka sta bila julija 1998
odkrita dva gnezdilna rova s po enim jajcem, junija
1999 pa je bil najden gnezdilni rov z vale~o ptico in
enim jacem. Na Palagru`i je bilo med avgustom in
septembrom 1997 odkritih pet zasedenih gnezdilnih
rovov (3 odrasle ptice in dva mladi~a). Ocenjujeva,
da kolonija na Palagru`i {teje najmanj 20 parov.
Glede na skupine rumenokljunih viharnikov,
opa`enih v bli`ini oto{kih gnezdi{~, bi na hrva{kih
otokih v Jadranu lahko gnezdilo od nekaj sto do nekaj
tiso~ parov teh ptic. 
Po razvitosti perja speljanih obro~kanih mladi~ev
bi lahko sklepali, da te ptice za~nejo valiti med
aprilom in majem in da mladi~i zapustijo kolonije,
gnezde~e v Jadranu, med septembrom in oktobrom.
Glede na redka zimska opa`anja teh ptic br`kone
dr`i, da nekatere izmed njih pozimi sicer ostanejo na
Jadranu, a da ima ve~ina izmed njih enake selitvene
navade kot viharniki sredozemske populacije.
Rumenonkljuni viharniki se pogosteje pojavljajo v
ju`nem Jadranu kot pa v severnem.
Tudi sredozemski viharnik Puffinus yelkouan naj bi
gnezdil na nekaterih oddaljenih otokih hrva{kega
Jadrana, toda edini dokaz o tem je poro~ilo o dveh
samicah, najdenih v gnezdilnih rovih na otoku
Svetac. Jate 500–1.000 sredozemskih viharnikov, ki
redno letajo vzdol` vzhodne jadranske obale, dajejo
misliti, da v Jadranu gnezdi ve~ sto parov teh ptic.
Sicer pa utegnejo biti nekateri izmed sredozemskih
viharnikov, pojavljajo~i se v Jadranu, negnezdilci ali
pa gnezdilci, ki prihajajo v Jadran iz neznanih delov
Sredozemlja.
Poletne in jesenske koncentracije povr{inskih rib v
severnem Jadranu, ki so najljub{i plen teh ptic, so
razlog, da sredozemski viharniki zapustijo svoja
gnezdi{~a na oddaljenih otokih v ju`nem Jadranu in
se odpravijo na lov v zgornji del severnega Jadrana.
Med spomladjo in jesenjo se primarna produkcija v
severnem Jadranu pove~a, z rastjo planktona pa se v
gornjem kotu Jadrana zbirajo ogromne jate
povr{inskih rib, predvsem v obmo~jih z mo~nim
dotokom sladke vode. Vzdol` vzhodnega Jadrana so
bile opa`ene skupine sredozemskih viharnikov, ki so
{tele of 500 do 1.000 osebkov, in sicer v Tr`a{kem
zalivu (septembra), Kvarnerju (junija) in severni
Dalmaciji (oktobra). Glede na poletno/jesensko
raz{irjenost teh ptic je produktivni gornji kot Jadrana
19
Acrocephalus 22 (104-105): 9 – 21, 2001
pomembno obmo~je prehranjevanja in golitve za
jadranske ptice in najbr` tudi za ptice iz drugih
obmo~ij Sredozemlja. Sezonska raz{irjenost opa`anj
ka`e na selitvene navade pri ve~ini jadranskih vihar-
nikov v zimskem ~asu.
Strako{ Hydrobates pelagicus je bil v vzhodnem
Jadranu odkrit ob ve~ prilo`nostih, in sicer med
junijem in novembrom. Glede na eno samo
opazovanje naj bi sicer gnezdil na oto~ku Jabuka,
vendar pa o zanesljivem gnezdenju ni kakih
otipljivej{ih dokazov.
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Arrived / Prispelo: 30.8.2000
Accepted / Sprejeto: 15.6.2001
21
Acrocephalus 22 (104-105): 9 – 21, 2001