During the springs of 2014 and 2015, and the winter of 2014/15, bird
survey was conducted in the forests of Petrova gora. Overall, 35 bird
species were registered. Songbird breeding densities were assessed using the point-count method. The most numerous species recorded were the Great Tit Parus major and the Eurasian Chaffinch Fringilla coelebs. The Stock Dove Columba oenas, categorised as vulnerable in Croatia, was for the first time recorded in this area. An overview of all bird species recorded at Petrova gora, in this and previous studies, is provided.Tijekom proljeća 2014. i 2015. godine te zime 2014/15. provedeno je deset terenskih izlazaka u šumama Petrove gore u sklopu kojih je zabilježeno 35 vrsta ptica. Ukupno su na Petrovoj gori, uključujući i prethodna istraživanja, zabilježene 44 vrste ptica. Korištena je
metoda točkastog transekta, a podaci su prikupljani i slučajnim opažanjima i zvukovnim vabom. Podaci prikupljeni metodom točkastog transekta iskorišteni su za izračunavanje procjene gustoće gnijezdećih populacija pojedinih vrsta, od kojih su najbrojnije velika
sjenica Parus major i zeba Fringilla coelebs. Golub dupljaš, koji je u Hrvatskoj kategoriziran kao osjetljiva vrsta, prvi je put ovim istraživanjem zabilježen na Petrovoj gori. Potrebna su daljnja istraživanja ptica otvorenijih staništa i grabljivica Petrove gore, kao
i ciljano istraživanje veličine populacije goluba dupljaša Columba oenas, vrste čiji je status ugroženosti gnijezdeće populacije u Hrvatskoj kategoriziran osjetljivom (VU)

Miloš Martinović

English

Tijekom proljeća 2014. i 2015. godine te zime 2014/15. provedeno je deset terenskih izlazaka u šumama Petrove gore u sklopu kojih je zabilježeno 35 vrsta ptica. Ukupno su na Petrovoj gori, uključujući i prethodna istraživanja, zabilježene 44 vrste ptica. Korištena je

metoda točkastog transekta, a podaci su prikupljani i slučajnim opažanjima i zvukovnim vabom. Podaci prikupljeni metodom točkastog transekta iskorišteni su za izračunavanje procjene gustoće gnijezdećih populacija pojedinih vrsta, od kojih su najbrojnije velika

sjenica Parus major i zeba Fringilla coelebs. Golub dupljaš, koji je u Hrvatskoj kategoriziran kao osjetljiva vrsta, prvi je put ovim istraživanjem zabilježen na Petrovoj gori. Potrebna su daljnja istraživanja ptica otvorenijih staništa i grabljivica Petrove gore, kao

i ciljano istraživanje veličine populacije goluba dupljaša Columba oenas, vrste čiji je status ugroženosti gnijezdeće populacije u Hrvatskoj kategoriziran osjetljivom (VU).During the springs of 2014 and 2015, and the winter of 2014/15, bird

survey was conducted in the forests of Petrova gora. Overall, 35 bird

species were registered. Songbird breeding densities were assessed using the point-count method. The most numerous species recorded were the Great Tit Parus major and the Eurasian Chaffinch Fringilla coelebs. The Stock Dove Columba oenas, categorised as vulnerable in Croatia, was for the first time recorded in this area. An overview of all bird species recorded at Petrova gora, in this and previous studies, is provided

Martinović, Miloš

Hrčak - Portal of scientific journals of Croatia

21Larus Vol. 50, 2015LARUSHrvatska akademijaznanosti i umjetnosti50(2015)21-28 str.2 tablice Zagreb 2015Primljeno 13. 9. 2015Prihvaćeno na sjednici Razreda za prirodne znanosti HAZU 26.11.2015.UDK 598.2 Original scientific paperIzvorni znanstveni članakBREEDING BIRDS OF PETROVA GORA: FOREST SONGBIRD DENSITIES AND AN OVERVIEW OF OTHER RECORDED SPECIESPtice gnjezdarice Petrove gore: gustoće šumskih pjevica i pregled drugih zabilježenih vrstaMiloš MartinovićPražnica 21,HR- 10000 Zagreb, Croatia ABSTRACTDuring the springs of 2014 and 2015, and the winter of 2014/15, bird survey was conducted in the forests of Petrova gora. Overall, 35 bird species were registered. Songbird breeding densities were assessed us-ing the point-count method. The most numerous species recorded were the Great Tit Parus major and the Eurasian Chaffinch Fringilla coelebs. The Stock Dove Columba oenas, categorised as vulnerable in Croatia, was for the first time recorded in this area. An overview of all bird species recorded at Petrova gora, in this and previous studies, is provided. INTRODUCTIONA large part of Petrova gora was protected in 1969 as “Petrova gora – Biljeg” significant landscape for its preserved forest habitats, landscape and historical values (Petrak 2011). “Petrovac ornithological park” was founded in the area in 2008. A search of existing ornithological data from the area has yielded only one prior survey of mostly qualitative nature (D. Radović, D. Kršić in litt.). The aim of this paper is to provide a fuller qualitative list of bird species of Petrova gora by integrating historical data with new ones, as well as to provide an estimate of densities of certain forest songbirds.e-mail: mmmmilos@gmail.com22Miloš Martinović: Breeding birds of Petrova gora - Forest songbird densities and an overview of other recorded species MATERIAL AND METHODSThe study took place at Petrova gora as a part of two separate projects, “Com-mon Bird Monitoring in Croatia” (CBM) and “EU Natura 2000 Integration Proj-ect” (NIP), during the springs of 2014 and 2015 and the winter of 2014/15. The position of the study area is approximately 45.28 – 45.35°N, 15.72° – 15.84°E. Less than 20% of forests are Sessile Oak Quercus robur while the rest are European Beech Fagus sylvatica forests. The highest peak of Petrova gora is Petrovac (512 m a.s.l.) (Petrak 2011). Forest songbirds densities were assessed using the point transect method. A list of recorded species of Petrova gora forests was supple-mented by anecdotal observations. The point transect methodology follows the one described in Bibby et al. 1992 and Gregory et al. 2004. Estimation of number of breeding pairs was mostly, but not exclusively, based on singing males; visual observation and other bird sounds were used in the absence of song. The methodology differed somewhat between the two projects: the inner band radius of point transects was 30 m in the CBM project and 50 m in the NIP project. Furthermore, the transect of the NIP project consisted of 10 points, each at a distance of at least 250 m, and 6 minutes of the counting time was used on each point. Transects of the CBM project consisted of 9 points, each at a distance of at least 300 m. Six minutes were spent on each point as well, but birds were counted during the last 5 min-utes only. All transects were completed before 9:30 AM. Three point transects were completed (one by the NIP methodology and two by the CBM methodol-ogy; 28 points altogether), and each transect was surveyed two times –in the early spring (6 April to 12 April) and in the late spring (18 May to 13 June), with a minimum of 41 and a maximum of 62 days between the visits. All transects were surveyed during the spring of 2014. Breeding densities of certain songbird species were assessed following Bibby et al. 1992. As most of the points were located in beech forests (23 points), songbird densities were assessed for beech forests only, thus excluding 5 points located in the sessile oak forests. The to-tal number of observed breeding pairs for each species was determined as the greater number of recordings per point between the visits. Species with only one observed breeding pair were excluded from the analysis, as well as wood-peckers and larger birds (such as the Eurasian Jay Garrulus glandarius and the Eurasian Golden Oriole Oriolus oriolus), which have relatively large territories (BWPi 2006).Sound lures were used between 9:30 and 11:30 PM on four points: two dur-ing the early spring period and two during the late spring. Scops Owl Otus scops, Long-eared Owl Asio otus, Tawny Owl Strix aluco, Ural Owl Strix uralensis and Eagle Owl Bubo bubo songs were played in succession from a car radio, lasting 1.5 minutes each and with 1 minute listening breaks between species.23Larus Vol. 50, 2015Birds were also recorded between the points of transects and throughout the area during midday in order to extend the bird species list of Petrova gora.RESULTSDuring ten field days in the area of Petrova gora, a total of 35 bird species (34 breeding) was recorded; added to 9 earlier findings (Radović & Kršić in litt, SUŠIĆ et al. 1988), it brings the total number of birds recorded in the area to 44 (Table 1). Almost one third (~32%) of the recorded species are canopy-nesting, with half of those being non-passerines. Secondary hole-nesters represent one quarter (25%) of the recorded species, and these rely on the 14% of woodpeck-ers as primary hole-nesting species. The shrub- and ground nesting niches each holds 14% of the species.Table 1: List of recorded bird species on Petrova gora, the status of their breeding population in Croatia (GN) (according to Tutiš et al. 2013), and nest site niche (according to Svensson et al. 2009, Kirin et al. 2011, Mitrus & Soćko 2004). Woodpeckers are marked as 1°hole - pri-mary hole nesters. Species with * in front of the scientific name were not observed during the breeding season and species with ** were recorded only in earlier surveys Tablica 1: Popis zabilježenih vrsta ptica na Petrovoj gori, status njihovih gnijezdećih popu-lacije u Hrvatskoj (GN) (prema Tutiš et al. 2013) i niša izgradnje gnijezda (prema Svensson et al. 2009, Kirin et al. 2011, Mitrus & Soćko 2004). Djetlovke su označene kao 1°hole - pri-marne dupljašice. Vrste s * ispred znanstvenog naziva nisu zabilježene u sezoni gniježđenja, a vrste s ** zabilježene su samo u ranijim istraživanjimaScientific name English name Croatian name GN Nest site nicheArdea cinerea Grey Heron Siva čaplja LC canopy**Accipiter gentilis Northern Goshawk Jastreb LC canopyButeo buteo Eurasian Buzzard Škanjac LC canopy**Hieraaetus pennatus Booted Eagle Patuljasti orao CR canopyColumba oenas Stock Dove Golub dupljaš VU holeColumba palumbus Common Woodpigeon Golub grivnjaš LC canopy**Streptopelia turtur European Turtle-dove Grlica LC shrubCuculus canorus Common Cuckoo Kukavica LC parasitic**Strix uralensis Ural Owl Sova jastrebača NT canopyStrix aluco Tawny Owl Šumska sova LC holeDryobates minor Lesser Spotted Woodpecker Mali djetlić LC 1°holeLeiopicus medius Medium Spotted WoodpeckerCrvenoglavi djetlić LC 1°holeDendrocopos major Great Spotted Woodpecker Veliki djetlić LC 1°holeDryocopus martius Black Woodpecker Crna žuna LC 1°hole24Miloš Martinović: Breeding birds of Petrova gora - Forest songbird densities and an overview of other recorded species Scientific name English name Croatian name GN Nest site nichePicus viridis Green Woodpecker Zelena žuna LC 1°holePicus canus Grey-faced Woodpecker Siva žuna LC 1°hole**Motacilla alba White Wagtail Bijela pastirica LC ground**Motacilla cinerea Grey Wagtail Gorska pastirica LC groundTroglodytes troglodytes Winter Wren Palčić LC groundTurdus viscivorus Mistle Thrush Drozd imelaš LC canopyTurdus philomelos Song Thrush Drozd cikelj LC shrubTurdus merula Eurasian  Blackbird Kos LC shrubErithacus rubecula European Robin Crvendać LC ground**Phoenicurus ochruros Black Redstart Mrka crvenrepka LC groundFicedula albicollis Collared Flycatcher Bjelovrata muharica LC holeFicedula parva Red-breasted Flycatcher Mala muharica LC hole*Regulus ignicapilla Firecrest Vatroglavi kraljić LC canopyPhylloscopus collybita Common Chiffchaff Zviždak LC groundSylvia atricapilla Blackcap Crnokapa grmuša LC shrubSylvia nisoria Barred Warbler Pjegava grmuša LC shrubParus palustris Marsh Tit Crnoglava sjenica LC holeParus major Great Tit Velika sjenica LC holeParus caeruleus Blue Tit Plavetna sjenica LC holeAegithalos caudatus Long-tailed Tit Dugorepa sjenica LC shrubSitta europaea Wood Nuthatch Brgljez LC holeCerthia familiaris Eurasian Treecreeper Kratkokljuni puzavac LC holeCerthia brachydactyla Short-toed Treecreeper Dugokljuni puzavac LC holeOriolus oriolus Eurasian Golden Oriole Vuga LC canopy**Lanius collurio Red-backed Shrike Rusi svračak LC shrubGarrulus glandarius Eurasian Jay Šojka LC canopyCorvus corax Common Raven Gavran LC canopy**Sturnus vulgaris Common Starling Čvorak LC holeFringilla coelebs Eurasian Chaffinch Zeba LC canopyCoccothraustes coccothraustes Hawfinch Batokljun LC canopy25Larus Vol. 50, 2015In the forests of Petrova gora, the highest breeding density was estimated for the Great Tit Parus major with 295 breeding pairs per square kilometre. It is fol-lowed by the Eurasian Chaffinch Fringilla coelebs and the European Robin Eritha-cus rubecula with an estimate of 156.2 and 138.8 pairs/km2, respectively, and by the Wood Nuthatch Sitta europaea and the Common Chiffchaff Phylloscopus col-lybita estimated to 112.8 pairs/km2 each. The total breeding density of all assessed species was 1,266.9 pairs/km2 (Table 2).Two Stock Doves were observed on June 9th 2015 near the northeast border of the Petrova gora area. The pair was identified both visually and by voice in a wooden patch surrounded by pastures and cultivated land.Table 2: Estimated breeding densities for certain songbird species (pairs/km²) in European Beech forests on Petrova goraTablica 2: Procijenjene gnijezdeće gustoće nekih vrsta pjevica (parovi/km²) u bukovim šumama Petrove goreScientific name Estimated densityTurdus merula 95.5Erithacus rubecula 138.8Ficedula albicollis 69.4Phylloscopus collybita 112.8Sylvia atricapilla 69.4Parus palustris 34.7Parus major 295Parus caeruleus 17.4Sitta europaea 112.8Certhia familiaris 43.4Certhia brachydactyla 34.7Fringilla coelebs 156.2Coccothraustes coccothraustes 86.8Total density 1266.9DISCUSSIONA total of 44 bird species was recorded in the area of Petrova gora, including the Booted Eagle Hieraaetus pennatus in 1952 (Sušić et al.1988), which is today classified as a critically endangered species in Croatia (Tutiš et al. 2013). Note-worthy are also the records of the Ural Owl Strix uralensis (Near Threatened) in 2009 (V. Tutiš pers. com) and the Stock Dove Columba oenas (Vulnerable) in 2015.The field research in 2014-15 was mostly concentrated on forest habitats of Petrova gora, and as a result 35 species were recorded there. The nine species from earlier surveys that were not recorded recently are mostly species of semi-26Miloš Martinović: Breeding birds of Petrova gora - Forest songbird densities and an overview of other recorded species open or open habitats that were not included in this study (Starling Sturnus vulgaris, Red-backed Shrike Lanius collurio, Black Redstart Phoenicurus ochruros, White Wagtail Motacilla alba), and birds of prey which are difficult to observe through the forest canopy (Goshawk Accipiter gentilis, Booted Eagle). Further-more, the Booted Eagle record is quite old and, given its status today, the species might not reside in the area any longer.The obtained data on community composition are similar to that from previ-ous studies in similar habitats (Kirin et al. 2011, Dumbović 2007), but the species abundance has some interesting differences. The estimated population density of the Great Tit is more than three times larger than in previous studies, as well as that of the Hawfinch Coccothraustes coccothraustes, while density estimates for the Blue Tit Parus caeruleus and the Marsh Tit Parus palustris are significantly lower. This change might indicate a bias in observing the above mentioned spe-cies in the field (e.g. recording Blue and Marsh Tits as Great Tits). However, these results may also be due to the fact that as much as 10 of the 23 studied points were situated between patches of forest of significantly different age, and this ap-parent higher habitat diversity might have contributed to the higher abundance of some species. It is also probable that the lower sample size of only 23 points included out in this analysis (compared to around 50 in the previous ones) con-tributed to these variations.Considering the different types of forests of Petrova gora, some species were observed mostly (the Lesser Spotted Woodpecker Dryobates minor) or only (the Red-breasted Flycatcher Ficedula parva) in the sessile oak forests. Furthermore, some species observed in beech forests of other Croatian mountains, like the Goldcrest Regulus regulus, Firecrest Regulus ignicapilla and Coal Tit Parus ater (Ki-rin et al. 2011, Dumbović 2007), were not observed in this study during the breed-ing season. Considering that these are all species commonly found in coniferous and mixed beech-fir forests (BWPi 2006, Svensson 2009), and that these types of forests are not present on Petrova gora, it is no surprise that the above mentioned species were not recorded in this study.Although the data of 69.4 breeding pairs/km2 might make it seem like the Blackcap was a relatively numerous forest species, it was mostly recorded in more open habitats like forest edges, thickets and near paths. It is among the most numerous species in those types of habitats, but cannot be considered a true forest species, as it was rarely recorded deeper in the woods.The most abundant species are fairly evenly distributed across nesting niches, with the Great Tit and Wood Nuthatch being the most common hole-nesters, the Eurasian Chaffinch and Hawfinch as the most common canopy-nesting spe-cies and the European Robin and Common Chiffchaff representing the ground-nesters. In comparison to the previous studies (Kirin et al. 2011, Dumbović 2007, Kralj & Radović 2005), the relatively low abundance of the Blackcap and the 27Larus Vol. 50, 2015absence of Song Thrush Turdus philomelos, both shrub-nesting species, might be explained by the fact that on Petrova gora few bushes can be found on the forest floor. Most of the shrub vegetation is located on forest and road edges, where the abundance of shrub-nesting species was the highest. The total estimated density of all recorded breeding species is similar to the one from the previous studies in similar habitats (Kirin et al. 2011). Further bird survey of different open habitats of the Petrova gora area, as well as a more detailed survey of birds of prey of the area is necessary. It is also advis-able to carry out a specifically designed and targeted survey of a larger extent in order to better estimate bird population densities, especially the population of the Stock Dove, a species which breeding population status in Croatia is classi-fied as Vulnerable (Tutiš et al. 2013).AcknowledgementsI would like to thank Iva Šoštarić, Petra Čulig, Josip Turkalj and Doroteja Šimunković-Novak for fieldwork assistance; Association BIOM, The State Insti-tute for Nature Protection (DZZP) and Jelena Kralj for preparing and outlining the fieldwork; my relatives in the region for providing logistic support; Milana Martinović and Krunoslav Koprivnjak for language improvements; again Jelena Kralj and Milorad Mrakovčić for commenting on drafts and Sanja Barišić for help with the data analysis. Further thanks to reviewers for valuable insight and com-ments. This study was financed by the projects “Common Bird Monitoring in Croatia” and “EU Natura 2000 Integration Project”.ReferencesBibby, C. J., Burgess, N. D., Hill, D. A. (1992): Bird Census Techniques. Academic Press Ltd., London. BirdLife International (2014): BirdLife taxononomy, ver. 7. http://www.birdlife.org/data-zone/info/taxonomyBWPi (2006): BWPi 2.0.1. Birds of the Western Palearctic Interactive DVD ROM, Oxford University Press & BirdGuides Ltd.Dumbović, V. (2007): Struktura zajednica ptica gnjezdarica u šumama Parka Prirode Papuk. Magistarski rad, Sveučilište u Zagrebu, Prirodoslovno-matematički fakultet. Gregory, R.D., Gibbons, D.W., Donald, P.F. (2004): Bird census and survey techniques. pp 17-56. In: Sutherland W.J., Newton I. et Green R.E. (eds.): Bird Ecology and Con-servation; a Handbook of Techniques. Oxford University Press, OxfordKirin, T., Kralj, J., Ćiković, D., Dolenec, Z. (2011): Habitat selection and the similarity of the forest songbird communities in Medvednica and Žumberak-Samoborsko Gorje Nature Parks. Šumarski list 9–10: 467-475.Kralj, J., Radović, D. (2005): Composition and density of breeding bird community in Mediterranean (Istria peninsula) and continental oak (Quercus robur L.) forests in Croatia. Pol. J. Ecol. 53(2): 269-274.28Miloš Martinović: Breeding birds of Petrova gora - Forest songbird densities and an overview of other recorded species Mitrus, C., Soćko, B. (2004): Natural Nest Sites of the Red-Breasted Flycatcher Ficedula parva in a Primeval Forest. Acta Ornithologica, 39(1):53-57.Petrak, M. (ed.), (2011): Značajni krajobraz ‘’Petrova Gora-Biljeg’’: Zaštićeno područje prirode. Javna ustanova za upravljanje zaštićenim prirodnim vrijednostima Karlovačke županije ‘’Natura viva’’, KarlovacSušić, G., Radović, D., Bartovsky, V. (1988): Znanstvena zbirka ptičjih svlakova Zavoda za ornitologiju JAZU. In: MEŠTOV, M., SUŠIĆ, G. (eds.): Ornitologija u Hrvatskoj. Razred za prirodne znanosti JAZU, ZagrebSvensson, L., Mullarney, K., Zetterström, D. (2009): Collins Bird Guide 2nd Edition. HarperCollins Publishers, LondonTutiš, V., Kralj, J., Radović, D., Ćiković, D., Barišić, S., (2013): Popis ptica Hrvatske – 2010. U: Crvena knjiga ptica Hrvatske. Ministarstvo zaštite okoliša i prirode, Državni zavod za zaštitu prirode, Republika Hrvatska, 218-237.SAŽETAKTijekom proljeća 2014. i 2015. godine te zime 2014/15. provedeno je deset terenskih izlazaka u šumama Petrove gore u sklopu kojih je zabilježeno 35 vrsta ptica. Ukupno su na Petrovoj gori, uključujući i prethodna istraživanja, zabilježene 44 vrste ptica. Korištena je metoda točkastog transekta, a podaci su prikupljani i slučajnim opažanjima i zvukovnim vabom. Podaci prikupljeni metodom točkastog transekta iskorišteni su za izračunavanje procjene gustoće gnijezdećih populacija pojedinih vrsta, od kojih su najbrojnije velika sjenica Parus major i zeba Fringilla coelebs. Golub dupljaš, koji je u Hrvatskoj kategoriziran kao osjetljiva vrsta, prvi je put ovim istraživanjem zabilježen na Petrovoj gori.Potrebna su daljnja istraživanja ptica otvorenijih staništa i grabljivica Petrove gore, kao i ciljano istraživanje veličine populacije goluba dupljaša Columba oenas, vrste čiji je status ugroženosti gnijezdeće populacije u Hrvatskoj kategoriziran osjetljivom (VU).

Ptice gnjezdarice Petrove gore: gustoće šumskih pjevica i pregled drugih zabilježenih vrsta

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