SRJ10262Volume501

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Tab. 9. The diet of Strix aluco in Slovakia, type D, +Chiroptera

Tab. 9. Potrava Strix aluco na Slovensku, typ D, +Chiroptera

diet )aluco Strix( owl tawny of diversity chronological and Spatial J: Obuch

The owl mostly used the rock chimney at the rock face as its diurnal rest place. There was one year when the owl used an overhanging rock which originally served asnightrestforravens(Obuch2007).Duringthelatest period the owl has mostly inhabited the Krpcovo cave. Thesamplesfromthefirstdecade(1978–1991)showed higher abundance of S. araneus, M. avellanarius and C. glareolusandthusbelongedrathertothesubtypeC2 withlowerabundancesofR. temporariaandS.betulina. Only after 1983 we could see the alternation of population peaks of A. flavicollis (1993,2000, 2007–2008) with years when Limacidae became dominant as the substitutional prey (1997, 1999, 2006, 2009). Faunistically significant was the finding of the garden dormouse (E. quercinus), which was found in fresh pellets collected in 1997 and 2004.

MuránskaplaninaMts.,dietarytypes.ThefirstdetailedsurveyattheMuránskaplaninaMts.wasconductedin 1979–1983(Obuch1985b).ThetopicofS.alucodietary types in the territory of the Muránska planina National Park was described in a separate study (Obuch 2004a). In Table 11 we can see the results from pellet sampling until the year 2010. 80% of the 17,544 food items collected belonged to type E. Using the MDFM methods (Obuch 2001), therefore, these kinds of samples mostly influenced the average, and diagnostic species for other food types stood out. In type E, the Limacidae family shows higher frequency than average (33.4%), whereas thepercentageinotherdietarytypesissometimesmuch lower. The most marked group of species with positive MDFMvaluefordietarytypeCcomesfromthetopofthe plateau and valleys of the northern part of the National Park,belongingtotheHorehronieregion.Themostsignificant(3+)distinguishingfeatureisthehighproportion ofS.betulina(3.6%),butalsootherspecies(2+)suchas

T.europaea,A.amphibius,M.agrestis,M.subterraneus,

R.temporariaandtheorderColeoptera.TypeBsamples fromthewarmestsitesatthesouthernedgeoftheplateau are dominated by forest rodent species including A. flavicollis and C. glareolus. The bat species N. noctula is more frequent in a single sample of type D and several samples of subtype G2 from the square inTisovec town containsynanthropicpasseriformspecies:P.domesticus,

D. urbicum, H. rustica and Apus apus.

Muránska planina Mts., type C (Appendix 21). The owl pellets of this type were found at the upper edge of the plateau (Jaskyňa pod Kľakom cave, Zbojská) and in the northern part of the plateau in the rocks of Malá Stožka Mt. and Župková Magura Mt., in the loft space

of a horse barn at the Pätina forester’s house and at the huntinglodgeinTrsteníkvalley.Attwosites(MaláStožka, Trsteník), the dominance of Limacidae was >20%, but the incidence of forest rodent species A. flavicollis and C. glareolus was low and Limacidae were not substitutional prey during population lows of these rodent species, as could be seen in the dietary type E.The pellet samples from the Pätina forester’s house were distinct for their higher proportional content of S. betulina and Coleoptera. The owl inhabited the forester’s house after it had been abandoned. The sample from the rocks at Župkova Magura above Dlhá valley is characterized by higher proportions of R. temporaria and N. fodiens. The samples from Zbojská, lacking S. betulina and showing anincreasedcontentoffivemammalspeciesareclassified as subtype C2 (Obuch 2004a).

MuránskaplaninaMts.,typeE(Table12).Thedietary typeEattheMuránskaplaninaMts.isrepresentedbypellet material from five sites, mainly collected on the southern slopes of the mountain range with prevalent beech forest cover. The samples from all of these sites were collected

during several seasons and we present them in separate timeline tables. A typical site of type E at the Muránska planina Mts. is the Šarkanica cave in the Martincová valley with the highest number of samples and a total sum of 6,527 prey items. The abundances of prey from this site were the closest to the average of the whole Muránska planina Mts. The elevated Voniaca valley shows the highestdominanceofthehazeldormouseM.avellanarius. Lower sites in Javorníkova and Javorníčkova valleys and at Brestová had the most dominant species M. arvalis and R.temporaria. At Brestová there was relatively high species diversity especially because of higher proportion of various passerines (Passeriformes). The eudominant speciesC.glareolus (13.3%)showedanevendistribution at all five sites.

Šarkanica cave (Appendix 22). The Šarkanica cave is located in the middle of the Martincová Valley in the ŠarkanicaNationalNatureReservewithpreservedclimax forestcommunities.Thecaveishardlyaccessible,located in the middle of a rock wall, so the owl experienced only low disturbance and large quantities of food remains ac-

cumulatedinthecave.Thereisnotimberloggingallowed within a 1 km radius of the cave. The fluctuations in the proportions of the diagnostic species can therefore be directly linked to the natural population cycles of several speciesofrodents.Therodentpopulationdynamicsinthis area is influenced by the seed crop of several tree species with beech being the most prevalent.

During a period of 31 years (1979 to 2010) 20 samples were collected at this site. The seasonal comparison 1979–1996 (Obuch 1997) shows a contrast between the peaksofA.flavicollisanditslowsreflectedinhigherproportionofLimacidaefamilyinthepellets.Aftercollecting additional samples in 2010, doubling the total number of prey items, the long-term trends became more pronounced. The incidence of Limacidae was markedly above average only in three periods: 1979–1980, 2005–2006 and 2009–2010. Between 1981–2005 there was an oscillation in proportions of the four most abundant mammal species: A. flavicollis, C. glareolus, M. avellanarius and

S. araneus. In January 2005 we could see the end of the rodent population increase after the rich seed crop in the

autumn of 2004. The sample from June 2005 contained averageproportionsofA.flavicollisandC.glareolus,but theproportionofLimacidaeincreasedaboveaverageand remained at high level throughout 2006.

Voniaca valley (Appendix 23). In the first years of the survey, an owl inhabited the caveVoniaca 1 and food samples were quite small. An increased proportion of Limacidae could be seen in the samples from the 1980’s. From 2000 the owl inhabited the cave Voniaca 2 and a rock chimney in the vicinity of the cave. The largest samplesfrom2005weredepositedduringthepopulation peak of the forest species A. flavicollis and C. glareolus. The eudominant species M. avellanarius (9.5%) showed an even distribution in all samples.

Javorníková and Javorníčková valleys (Appendix 24). In 1979 we found detritus and pellets of S. aluco in a small cave located in the Javorníková valley.After the opening of the hiking trail leading to a local waterfall, the owl abandoned this place. In 1992, owl pellets were found between trees standing at the upper edge of a rock faceintheJavorníčkovávalleyapproximately1kmfrom

theformerfindingplace.Since2000,theowlpelletswere deposited on the south-western edge of the rocks. The sample from the Javorníková valley contained increased proportionsofM.arvalis andR.temporaria,whereasthe firstsamplefromtheJavorníčkovávalley,thelowcontent of A. flavicollis was compensated by other mammal speciessuchas:C.glareolus,M.avellanariusandS.araneus. Two peaks of A. flavicollis and two peaks of Limacidae were identified in the samples collected till 2000. On the basisofthelastfoursamples,thedietoftheowlinhabiting this place was classified as type E.

Brestová(Appendix25).In1979,wecollectedasubrecent sample from 2–10 cm of soil and fresh pellets fromthe0–2cmtopsoillayeronarockledgeatthehigh rock chimney at Brestová, located on the right side of the entrance to the Hrdzavá dolina valley.The subrecent sample contained increased proportion of M. arvalis and the fresh pellets contained increased proportion of R.temporaria.After1983apairofravensbuilttheirnest

on a rock above the chimney and the owl then abandoned the site. In 1996 we found pellets at a different site below a rock overhang and a hollow beech tree and in 2005 also at the Hurbanovská cave. Since there were considerable time gaps between the pellet samplings, we could not observe alternations of the population peaks of A. flavicollis and periods of higher proportion of Limacidae in the food of S. aluco. However, the total ratio of dominant species matches the description of the dietary type E.

Odštiepenáskalarock(Appendix26).Anindividualof S.alucousedtherockmassifoppositetoOdštiepenáskala rock on the left side of the Hrdzavá dolina valley as its diurnalrestplace.Sincethe1990’soneoftherockceilings in this massif has been used by climbers as a shelter.This has led to frequent disturbance of the owl and therefore lowernumbersofpelletsatthissite.Thedetrituscollected in1979containedincreasedproportionsofM.arvalisand R. temporaria. The highest proportion of Limacidae was

found in the pellets collected betwen 1979 and 1982. In the first half of the 1980’s, there was a wind throw at the Odštiepená Rock and a large clearing formed as a result. After this event the diet of the owl showed a marked increaseinthecontentofM.avellanariusandSorexminutus. The last several pellet samples were collected at uneven time intervals and smaller samples were collected. The positive MDFM values of A. flavicollis and C. glareolus in the samples from 1996, 2002 and 2003 do not allow us to confirm if their populations peaked in these years.

TypeF:floodplainforests.Thedescriptionofthisdietary type in S. aluco has been published in a separate paper (Obuch 2003) on the basis of samples from eleven sites inthevicinityoftheriversMorava,Danube,Latoricaand Tisa.Thisdietarytypeischaracterizedbythehighproportion of frogs (Table 13).After the limit of the proportion of Anura was set at 15%, three of the presented samples did not conform to this condition and were reclassified

as type G. The frog species R. temporaria did not occur in the samples of this dietary type. The frog species R.dalmatinaandR.lessonaearedifficulttodiscernfrom the characteristics of the os ilium and I therefore present them collectively as green frogs in the synklepton Rana kl. esculenta. This synklepton occurred more frequently at three sites close to the River Morava and Jurský Šúr. Inthesethreesamplesthemorefrequentspeciesincluded R. ridibunda, at two sites there was an increased abundance of Pelobates fuscus and Hyla arborea. The most dominant species in the food of S. aluco in the Latorický luh National Nature Reserve was Rana arvalis.

Mammals (Mammalia, 40.5%) represent an equally frequent prey for S. aluco as frogs. The proportion of birds (Aves, 12.2%) in the diet of S. aluco, especially of the family Fringillidae, was rather high. The soft and hard floodplain forests form larger stands along the large rivers. Some of them are partially recultivated for the more timber-productive monotypic poplar stands.

From the recording of vocalizations, Lešičko (2001) confirmed the presence of 31 breeding pairs of S. aluco in the inundation zone of the River Danube at Bodíky in a 13.6 km2 area of the floodplain forest. However, the hunting range of the owls often reached beyond the boundaries of the floodplain forest and they often searched for prey in the surrounding agricultural land. In our samples we see that the mammal species with the highest dominance was M. arvalis (13.2%). Further abundant species included the non-forest species of the Apodemus genus. Frogs become the dominant prey item ofS.alucoonlyatsites,wheretheyareveryconcentrated, suchasinthebayousorotherdammedwaterbodies.For exampleintheJurskýšúrNationalNatureReserve,frogs showedadominanceof18.5%inthefloodedalderforest, but in the drier Panonský háj only 3.2%. The owl could hunt the present frog species also in the water bodies outside the floodplain forest.An example of these is the

Pokoradzské jazierka lakes National Nature Reserve (Appendix6),wheretheR.temporaria isalsopresent.In Table 13 only the diagnostic and more frequent species canbeseen,becausethefulllistsofspeciesandseasonal changes at some locations have already been published (Obuch 2003).

Type G from the strongly human-influenced environment. S. aluco was originally a forest hunter, but it can adapt to hunting in other environments and utilize different food sources. Part of its population lives in the vicinityofhumansettlementsandhuntsinnon-foresten- vironments.IntheconditionsofCentralEurope,thenon- -forestenvironmentsaresustainedbyhumanactivityand formeitheragriculturalorurbanizedland.InSlovakia,the mostdominantsmallmammalspeciesinagriculturalland is the common vole (M. arvalis). This species makes up themostimportantfoodsourceforseveralspeciesofbirds