ACROCEPHALUS 116.qxd 26.11.2003 14:18 Page 21 O Acrocephalus 24 (116): 21 – 27, 2003 Baillon’s Crake Porzana pusilla on the lower Neretva river: notes on a possible breeding location in southern Dalmatia Pritlikava tukalica Porzana pusilla ob spodnjem toku reke Neretve: zapiski o verjetni gnezditvi v ju`ni Dalmaciji Peter Sackl 1 , Luka Boži2 & Borut [tumberger j Steiermärkisches Landesmuseum Joanneum, Forschungsstätte “Pater Bl. Hanf am Furtnerteich, Raubergasse 10, A – 8010 Graz, Austria, e-mail: peter.sackl@stmk.gv.at 2 P * 1 f CT m f\r \ A *l Sl * Mill * r~\ • l 1 intarjeva 16, M – 2106 Maribor, Movenia, e-mail: luka.bozicwsiol.net 3 ~-,. , , /1 CT T-too *-•• il Sl • *l l r~\ • I Cirkulane 41, M – 2282 Cirkulane, Movenia, e-mail: stumbergerwsiol.net 1. Introduction Despite its extensive distribution which encompasses Australasia, sub-Saharan Africa and Eurasia, Baillons Crake Porzana pusilla belongs to the least-known breeding birds of the western Palearctic. This is due to its nocturnal and largely secretive habits. In Europe the species is a rare and erratic breeder in marshlands, flooded meadows, lowland floodplains and river deltas of the temperate, Mediterranean and steppe climate zones. While the nominate race P. p. pusilla occurs in Russia and Asia eastwards from the Black Sea and Caspian Sea, the distribution of P. p. intermedia is restricted to small, fragmented and ephemeral breeding areas in Morocco, and in southern, western and central Europe (Glutz von Blotzheim et al. 1973, Cramp 1980, Taylor & van Perlo 1998). Apart from its European strongholds on the Iberian Peninsula, where population numbers are estimated at 3010 – 5100 pairs (SEO/BirdLife 1997, Heath et al. 2000), scattered populations exist on the Balkan Peninsula northwards to the floodplains of the Carpathian Basin and Danube delta in Hungary and Romania (Ciochia 1992, Gorman 1996, Magyar et al. 1998, Munteanu 1998). In former Yugoslavia, Baillons Crake was found regularly in the riverine lowlands of eastern Croatia and northern Serbia, where the species bred in small numbers in the Baranja, Slavonija, Posavina, Pokuplje and Vojvodina regions (Matvejev & Vasi} 1973, Kralj 1997, Ra{ajski 1997, Luka~ 1998). With population numbers estimated at < 11 - 100 pairs, Baillons Crake is assessed as being critically endangered in Croatia (Luka~ 1998). In contrast to the central Balkans only scattered records exist for the western part of the Balkan Peninsula since the late 19th century. Almost all records concerning the region appear to relate to migrants (Csörgey 1903, Reiser 1905 & 1939, Matvejev & Vasi} 1973, Kralj 1997, Handrinos & Akriotis 1997, Luka~ 1998, Rucner 1998). The only, but vague, evidence for nesting on the western Balkans consists of: (1) On 10 Jun 1894 the dog of Ludwig von Führer caught an ash-grey male Porzana crake with an incubation patch in Humsko blato on Lake Skhoder. Unfortunately the bird was heavily mashed by the retrieving dog and consequently was not preserved. Later Reiser & Führer (1896) mentioned the case with much regret, because they were unable to decide retrospectively whether the specimen concerned Little P. parva or Baillons Crake; (2) In the early morning of 5 Jul 1959 Géroudet (1965) heard rattling calls of birds unknown to him in three locations throughout the marshlands of Hutovo blato on the lower Neretva river (Bosnia and Hercegovina). According to recordings of the advertising calls of Baillons Crake he later concluded that the callings he had heard in Hutovo blato may possibly have indicated the presence of the species. His report was later cited by many authors as the first evidence for breeding in the region (Matvejev & Vasi} 1973, Kralj 1997, Luka~ 1998); (3) In a review of the birds of the Ulcinj area in southern Montenegro, Vasi} (1979) quotes a personal comment by M. Shepherd, who had heard the callings of Baillons Crake in the salt-works of Ulcinj on 5 May 1975, but considers Shepherds report insufficiently well documented; (4) More recently a possible breeding locality in the surroundings of Knin (Croatia) and (5) three isolated breeding entries for Albania were recorded on the distribution maps in the EBCC Atlas of European Breeding Birds (Bijlsma 1997) and the Concise Edition of The Birds of the Western Palearctic (Snow & Perrins 1998). We report here on a small population in southern Dalmatia (Croatia), where we have found evidence of breeding on the lower Neretva river downstream of Hutovo blato. 21 O ACROCEPHALUS 116.qxd 26.11.2003 14:18 Page 22 P. Sackl et al. : Baillons Crake Porzana pusilla on the lower Neretva river: notes on a possible breeding location in southern Dalmatia 2. Study area and methods Between 26 Apr and 2 May 2001 we visited, as part of a group of field ornithologists organized by Borut [tumberger of DOPPS/BirdLife Slovenia at the request of the Institute of Ornithology of the Croatian Academy of Sciences and Arts in Zagreb, the valley of the lower Neretva river in southern Dalmatia. Our small Slovene-Austrian team, which resided in the town of Metkovi}, was complemented by Dominik Bombek, Matja` Ker ~ek, Luka Koro{ec, Primo` Kmecl, Barbara Pislak, Jakob Smole, Greta and Karmen [tumberger. The main objective of the expedition was to investigate the presence and status of Purple Swamp-hen Porphyrie) porphyrio, as well as to carry out an evaluation of population numbers of Great Bitterns Botaurus stellaris nesting in marshlands along the lower Neretva. The study area encompasses the depressions (dolina) Figure 1: Study area in the lower Neretva river valley in southern Dalmatia (Croatia) with black circles (= approximate location of callers) indicating the distribution of calling groups of Baillon’s Crake Porzana pusilla during late April and early May 2001. (white areas - inland water surface, bright grey area - Neretva river valley, dark grey area - hilly surrounds) Slika 1: Območje raziskave v spodnjem delu reke Neretve v južni Dalmaciji (Hrvaška): črni krogci (= približna lokacija oglašajočih se ptic) ponazarjajo distribucijo klicalnih skupin pritlikave tukalice Porzana pusilla med koncem aprila in začetkom maja 2001 (belo obarvana območja = vodne površine; svetlo sivo območje = dolina reke Neretve; temno sivo območje = hribi) ACROCEPHALUS 116.qxd 26.11.2003 14:18 Page 23 Acrocephalus 24 (116): 21 – 27, 2003 Table 1: Records of calling Baillon’s Crakes Porzana pusilla in the lower Neretva river valley, Dalmatia in spring 2001, at Lake Kuti and between the villages of Mislina and Trojavina. Tabela 1: Podatki o klico~ih pritlikavih tukalicah Porzana pusilla v spodnjem delu doline reke Neretve, Dalmacija, spomladi leta 2001, pri jezeru Kuti in med vasema Mislina in Trojavina. Date/ Location/ datum lokacija Time/ Number of birds, behaviour/ Observers/ ~as {t. ptic, vedenje opazovalci 27.4. Jezero Kuti, S Bad`ula 20.30 - 21.05 27.4. Blato, Podgrede evening 29.4. Jezero Kuti, - 20.00 Mislina - Trojavina 29.4. Jezero Kuti, S Bad`ula - 20.00 - 21.30 and Bad`ula - Mislina -Trojavina 30.4. Jezero Kuti, S Bad`ula 20.40 - 22.30 and Bad`ula - Mliniste 1.5. Jezero, Modro Oko - Osac 20.35 - 20.40 4 - 5 males calling spontaneously (warm, windless, very dark and moonless) 1 male calling spontaneously 2 males calling spontaneously 50 - 70 m from road (around 20 minutes after sunset) no reaction to playbacks; birds between Mislina and Trojavina silent, no reaction to playbacks along the whole section Badzula -Mislina - Trojavina no reaction to playbacks (warm, windless, bright moonlight) 2 males calling spontaneously close to road (warm and windless) L. Bo`i~ & P. Sackl D. Bombek L. Koro{ec & B. [tumberger L. Koro{ec & B. [tumberger L. Bo`i~ & P. Sackl P. Kmecl & B. [tumberger covered by extensive wetlands between the borderline to Bosnia and Hercegovina and the town of Opuzen near the estuary of the Neretva river at the Adriatic coast (Figure 1). With core wetland areas not accessible without boats we performed 42.2 km of synchronized transect counts - excluding a 6.7 km boat trip on Lake Kuti - along the periphery and along dikes crossing the marshlands with 3 - 4 teams each consisting of 2 – 3 observers during early morning (5.00 – 07.30 CET) and late evening (17.30 – 21.00 CET). To stimulate territorial calls at 73 check-points along transects (= 1.7 per km), taped playbacks of advertising and territorial calls of Purple Swamp-hen and Great Bittern were played for 5 – 10 minutes. In addition, on 30 – 40% of all check-points, when rails were not calling spontaneously, we also tested with the help of taped playbacks for the presence of Water Rail Rdllus aquaticus, Spotted Porzana porzana, Little and Baillon’s Crake. Except for a short rain shower during early morning of 28 April, when no counts were performed, overall windless, warm and sunny weather conditions with changing overcast prevailed. A total of 64 km2 of wetlands, with 56.4 % homogenous reedbeds, 22.3% marshlands covered by lower vegetation and 21.3% drained wetland areas, were investigated (Figure 1). 3. Results All Baillons Crakes recorded during our surveys on the lower Neretva were initially found by the advertising and territorial calls of spontaneously calling birds (Table 1). We heard calling males on four locations, with the most dense concentration of 4 – 5 callers on 27 Apr in the southeastern section of Lake Kuti south of Bad`ula, close to the frontier guard into Bosnia and Hercegovina. The following day, two other spontaneously calling birds were heard in the same area 1.7 km north of Bad`ula, near the road between the small villages of Mislina and Trojavina. In the marshlands north of the Neretva river another solitary male was heard in the extensive Blato of Podgrede, east of Sv. Vid. In addition two calling males were found on the Lake of Modro Oko between Komin and Rogotin, close to the estuary of the Neretva river, on 1 May (Figure 1). Vegetation characteristics where calling crakes were recorded, except in the Lake of Modro Oko, correspond to those summarized by Glutz vo n Blotzheim et al. (1973), Cramp (1980) and Taylor & van Perlo (1998). Most birds were calling from the edge of extensive wetland depressions characteristic of the area, in shallow, seasonally or irregularly flooded 23 ACROCEPHALUS 116.qxd 26.11.2003 14:18 Page 24 P. Sackl et al. : Baillons Crake Porzana pusilla on the lower Neretva river: notes on a possible breeding location in southern Dalmatia marshlands and submerged meadows covered by low sedges Carex sp., soft-rush Juncus sp., bulrush Scirpus sp. and other relatively fine-stemmed vegetation intermingled with tall stands of Reed Phragmites communis. On Lake Kuti, calling places of at least one or two males were near floating vegetation close to deeper, more open water (Figure 2). But due to darkness and a deep canal between the road and their calling sites, we were not able to locate the position of these birds exactly. Between Mislina and Trojavina the species was found in a partly submerged meadow dominated by low sedges and fragmented stands of dense reed. In contrast, both birds heard on 1 May were calling near the edge of extensive homogenous reed beds close to the road in Modro Oko (cf. Table 1). Figure 2: Habitat of Baillon’s Crake Porzana pusilla at Lake Kuti near Bad`ula in the lower Neretva river valley, Dalmatia, May 2001. Males were found calling close to the edge (right) and more to the centre of the area behind open water in the background (photo: P. Sackl). Slika 2: Habitat pritlikave tukalice Porzana pusilla ob jezeru Kuti pri Bad`uli v spodnjem delu reke Neretve, Dalmacija, maj 2001. Samci so se ogla{ali v bli`ini roba (na desni) in bolj proti sredi{~u obmo~ja onkraj odprtih voda v ozadju (foto: P. Sackl). Whereas transect counts were done during the evening as well as early morning, spontaneous calling activity of Baillon’s Crake appeared to be restricted to late evening hours with almost all calling recorded towards the end of transect counting between 20.00 and 21.00 CET, i.e. 20 min to 1 hour after sunset (Table 1). Perhaps more important, calling activity appeared to be largely reduced after 27 Apr. Except for a few interruptions, when suddenly and simultaneously all crakes ceased to call, all birds were calling continually when we first encountered them on Lake Kuti in the late evening of 27 Apr. During one of the breaks we managed to provoke continuous calling bouts by using taped playbacks. Later the same evening, we had the impression that at least some birds moved around while calling, possibly indicating courtship flights invisible to us owing to darkness (cf. Glutz von Blotzheim et al. 1973, Taylor & van Perlo 1998). In contrast, no crakes were found calling on 29 and 30 Apr, and no response to playbacks was provoked on Lake Kuti during later visits (Table 1). On both occasions, contrary to the situation on 27 Apr of deep darkness owing to an approaching rain front, the bright moonlight night was filled with extraordinarily loud choruses of frogs Runa X ridibunau and Common Tree Frog Hyla arborea. Nearest neighbour distances between solitary callers and/or calling groups on the lower Neretva (Figure 1) varied from 1.7 to 12.2 km (x = 8.2 km, n = 4). With 9 – 10 calling birds recorded we are neither able to rule out double counts between different transects nor the possibility that we missed other crakes in the area during our study. However, based on the assumption that advertising calls of Baillon’s Crake are audible for 150 – 250 m (cf. Glutz von Blotzheim et al. 1973) and according to a total of 42.2 km of line transect surveyed, overall densities for wetland areas in the region can be roughly estimated at 0.4 – 0.8 birds /km2. 4. Discussion In the course of the 20 century the avifauna of the lower Neretva river valley was intensively studied by Rucner (1953 & 1993). In spite of long-term collecting and bird-watching in the area he did not find Baillon’s Crakes. Nevertheless, in his most recent monograph on the bird fauna of the lower Neretva, Rucner (1993) listed Baillon’s Crake as a breeding species for the area without giving further details. However, first evidence for breeding in the valley of the lower Neretva river was reported by Géroudet (1965), who heard rattling calls which he later thought might have concerned the species in Hutovo blato, 5 km upstream of our study area. Other solitary birds recorded in Dalmatia during the last century were collected or sighted outside the nesting season; i.e. a male shot in Strobe~ near Split on 3 Apr 1959 and another male seen on 29 Sep 1988 in Torak Lake on the Krk river (Reiser 1939, Piasevoli & Pallaoro 1991, Stip~evic 1996, Kralj 1997). Evidence for the breeding of the species on the western Balkans is clearly based on records of calling 24 ACROCEPHALUS 116.qxd 26.11.2003 14:18 Page 25 Acrocephalus 24 (116): 21 – 27, 2003 birds only. Many aspects of the population dynamics, ecology, breeding biology, and behaviour of Baillons Crake are still insufficiently studied. Given our somewhat confusing data concerning the calling activity between late April and early May 2001, the breeding status of the species for the western Balkans is still inconclusive. However, territorial and courtship behaviour of Baillons Crake is generally regarded to be similar to that of other, better studied Porzana species. In particular the hard, dry rattling calls of the species, probably given by males only, the formation of small calling groups, and courtship flights may primarily function as advertising calls and mating displays important for pair-formation and subsequent courtship (Glutz von Blotzheim et al. 1973, Cramp 1980). Locating territorial males by means of their advertising calls is a matter of routine in breeding surveys and census work for Corncrake Crex crex, Water Rail and Spotted Crake (e.g. Gilbert et al 1998). According to Feindt (1968) and Szabó & Viszló (2001), advertising and territorial calls should, in the same way, be useful for population surveys of Baillons Crake. Recently the method was used for the species in the more densely populated parts in its breeding range (cf. Marchant & Higgins 1993, SEO/BirdLife 1997, Taylor & van Perlo 1998). Male Corncrakes are known to reduce their nocturnal calling activity drastically for a few nights immediately after they are mated, while Spotted Crakes call only until they are mated and keep silent for the rest of the breeding season (e.g. Tyler & Green 1996, Schäffer 1999). During a study in Austria’s Enns river valley (1998 – 2000), calling groups of Corncrakes (< 10 callers), regularly ceased calling during late May to early June, with a second peak of calling activity between late June and mid-July (H. Faber, P. Sackl & L. Zechner unpubl.). A similar reduction of calling activity is reported by male Baillons Crakes by Feindt (1968), Becker (1983) and Szabó & Viszló (2001). Correspondingly these authors emphasize that, in closely investigated cases, males ceased to call immediately after pair formation and/or at the start of egg laying (cf. also Glutz von Blotzheim et al. 1973, Taylor & van Perlo 1998). The period of time between the arrival of a female and the completion of clutch, and the period of calling activity for a solitary male at nesting sites in Lower Saxony (Germany), is given by Becker (1983) as 9 and 3 days, respectively. Calling activity of Baillons Crake may further depend on external factors like weather conditions, the volume of noise made by frogs or the intensity of moonlight (Table 1), the latter possibly affecting predation risk in habitats covered by low, more open vegetation preferred by the species. However, our data from the lower Neretva correspond to the calling phenology and calling characteristics during courtship and pair formation described for Corncrakes and other Porzana species. With timing of egg laying presumably depending on water level (Feindt 1968, Becker 1983, Szabó & Viszló 2001), our study apparently coincided with the initial stages of pair formation and egg laying. For southern and central Europe the latter is estimated by Glutz von Blotzheim et al. (1973) and Cramp (1980) to be early to mid-May. Although in Hungary most clutches were found between mid-May and late June, Szabó & Viszló (2001) mention a single clutch for early May and another one with already hatched chicks on 21 May. In The Netherlands in the 20 century, nests with eggs were found from 25 May – 23 June, nests with chicks or adults with chicks between 23 Jun and 5 Aug, and juveniles mainly in August (van den Berg & Bosman 2001). Apparently, breeding in the Netherlands is later than in central Europe. In more southern breeding areas a clutch of five eggs was found in the Azraq marshes of Jordan on 17 Apr 1963 (Andrews 1995) and in the Nile delta in Egypt adults in breeding condition and with downy young, respectively, were collected on 17 Apr 1917 and on 1 May 1920 (Goodman & Meininger 1989). Accordingly, Taylor & van Perlo (1998) correlate breeding condition and egg laying for the southern Mediterranean and the Middle East with April – May. The wetland depressions of the lower Neretva are obviously situated within the climatic zone suitable for nesting and within the overall distribution of the species. In comparison to densities of the possible race obscura” reported for some wetland areas of tropical Africa (Taylor & van Perlo 1998) and for P. p. palustris in Australia, our estimate of 0.4 – 0.8 birds / km2 is very low, but close to maximum densities of 5 birds / 509 ha found at Thompsons Lake Nature Reserve, Western Australia, 1981- 88 (Marchant & Higgins 1993). Large sections of marsh- and wetlands on the lower Neretva were reclaimed for agriculture, road building and urban development during the last decades. Although all wetlands in the area, including designated IBA and RAMSAR sites, are heavily disturbed by excessive hunting ([tumberger unpubl.), suitable marshland nesting habitat for Baillons Crake is apparently still widespread throughout the river delta and lower Neretva river valley. However, based on the evidence presented we conclude that the species is 25 O P. Sackl et al. : Baillons Crake Porzana pusilla on the lower Neretva river: notes on a possible breeding location in southern Dalmatia ower Neretva river: notes on a possible breeding location ACROCEPHALUS 116.qxd 26.11.2003 14:18 Page 26 probably a sparsely distributed and possibly erratic breeding bird in the area, a fact hitherto overlooked by many ornithologists. Summary Apart from very vague evidence for nesting, most records of Baillons Crake Porzana pusilla from the western Balkans along the coast of the Adriatic Sea relate to migrants. Between 26 Apr and 2 May 2001, 64 km2 of extensive marsh and wetland areas were investigated for the presence of Purple Swamp-hen Porphyrio porphyrio, Great Bittern Botaurus stellaris, Water Rail Rallus aquaticus and crakes Porzana sp. by 42.2 km of transect counting along the lower Neretva river valley between the border to Bosnia and Herzegovina and the town of Opuzen in southern Dalmatia (Croatia). Although we used playbacks of advertising and territorial calls of Baillons Crake on 20 – 30 check points along transects, the species was only found during our surveys by spontaneously calling birds. We recorded Baillons Crakes in four locations from solitary calling birds and from small calling groups of 2 – 4 (5) birds with the most dense concentration of 4 – 5 callers in the south-eastern section of Lake Kuti, south of Bad`ula. Altogether we were able to locate 9 – 10 calling birds in the area, i.e. 0.4 – 0.8 birds / km2 of wetlands investigated. Nearest neighbour distances between solitary callers and/or calling groups varied from 1.7 – 12.2 km. Over the period of the study two repeatedly visited calling groups at Lake Kuti appeared to reduce their spontaneous calling activity until 29 Apr, which seems to be in accordance with published evidence of a drastic reduction of nocturnal calling activity after pair formation and egg laying. Given the location of our study area within the overall distribution area of the species, the time of season and the characteristics of calling activity which we found on the lower Neretva, we conclude that the species - overlooked by many ornithologists – is probably a sparsely distributed breeding bird in the area. The first evidence for nesting on the western Balkans is based on calling birds heard in July 1959 in Hutovo Blato (Bosnia and Herzegovina) on the lower Neretva, 5 km upstream from our study area and in the salt-works of Ulcinj (Montenegro) in early May 1975. Povzetek Ve~ina podatkov o pojavljanju pritlikave tukalice 26 Porzana pusilla na zahodnem Balkanu vzdol` Jadranskega morja – poleg nekaj sicer zelo neprepri~ljivih dokazov” o gnezdenju te vrste v tem obmo~ju – zadeva njeno selitveno obdobje. Med 26.4. in 2.5.2001 smo pregledali 64 km2 mokri{~, da bi pre{teli sultanke Porphyrio porphyrio, bobnarice Botaurus stellaris, moko`e Rallus aquaticus in tukalice Porzana sp. vzdol` 42,2 km dolge ~rte transektov v spodnjem delu reke Neretve med bosansko-hercegovsko mejo in mestom Opuzen v ju`ni Dalmaciji na Hrva{kem. ^eprav smo na tridesetih to~kah ob transektih uporabljali posnetke teritorialnega ogla{anja pritlikave tukalice, smo jih med popisom na{li le med njihovim spontanim ogla{anjem. Zabele`ili smo jih na {tirih lokalitetah, kjer so se ogla{ale posami~no, in v skupinah od 2 – 4 (5) ptic z najve~jo koncentracijo 4 – 5 ogla{ajo~ih se ptic v jugovzhodnem delu jezera Kuti ju`no od Bad`ule. Skupaj nam je v raziskanih mokri{~ih uspelo locirati 9 – 10 ogla{ajo~ih se pritlikavih tukalic, t. j. 0,4 – 0,8 ptic / km2. Najmanj{e razdalje med posami~no ogla{ajo~imi se pticami in/ali klicalnimi skupinami so se sukale med 1,7 in 12,2 km. V ~asu raziskave sta se dve klicalni skupini pritlikavih tukalic ob jezero Kuti nehali spontano ogla{ati 29.4., kar je v skladu z objavljenimi podatki o drasti~nem zmanj{anju no~nega ogla{anja, ko se ptice za~nejo dru`iti v pare in le~i jajca. Glede na lokacijo preu~evanega obmo~ja znotraj celotnega obmo~ja raz{irjenosti vrste, letnega ~asa in zna~ilnosti ogla{anja ob spodnjem toku reke Neretve menimo, da je vrsta – ki so jo mnogi ornitologi tu o~itno prezrli – najbr` redko raz{irjena gnezdilka v obravnavanem obmo~ju. Prvi dokazi o gnezdenju pritlikave tukalice na zahodnem Balkanu zadevajo ogla{ajo~e se ptice, zabele`ene julija 1959 v Hutovem blatu (Bosna in Hercegovina) v spodnjem delu reke Neretve kakih 5 km severno od na{ega obmo~ja raziskave in v za~etku maja 1975 v Ulcinjskih solinah (^rna gora). References Andrews, I.}. (1995): The Birds of the Hashemite Kingdom of Jordan. - Privately published, Musselburgh, UK. Becker, P. 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