Fossil Population Structure and Mortality of the Cave Bear From the Mokrica Cave (North Slovenia)

Abstract

Izvleček UDK 902.035:569.74(497.4) Irena Debeljak: Struktura fosilne populacije in umrljivost jam skega medveda iz Mokriške jame (severna Slovenija): Struktura fosilne populacije jamskega medveda iz Mokriške jame je bila proučena z namenom, da bi dobili nove podatke o vedenju in umrljivosti te izumrle vrste. Starost ob smrti je bila ocenjena za 128 različni� osebkov, in sicer na podlagi analize cementni� prirastnic, formiranosti korenine in obrabe krone levi� M 1 zob. Po frekvenčni distribuciji primerkov v enolet-ni� intervali� la�ko ocenimo trend umrljivosti v različni� življenjski� obdobji� in ji� interpretiramo glede na podatke o današnji� medvedi�. V prvotni mrtvi združbi so po vsej verjetnosti prevladovali mladiči. Izjemno kr�ki molarji manj kot 6 mesecev stari� živali se niso fosilno o�ranili. Enoletniki so najbolj številčno zastopana starostna skupina v fosilni populaciji iz Mokriške jame. Umrljivost je drastično upadla, potem ko so jamski medvedi preživeli svojo prvo �ibernacijo v drugi zimi. Najnižja stopnja umrljivosti je bila ugotovljena za starostno obdobje 9-15 let, ko so bili jamski medvedi očitno na vr�uncu moči. Z analizo cementa ugotovljena najstarejša starost znaša okoli 30 let, kar kaže, da je bila najdaljša življenjska doba podobna kot pri današnji� medvedi�. Analiza zobni� tkiv je pokazala, da je bila umrljivost v jami sezonsko omejena-večina živali je poginila pozimi in zgodaj spomladi. Spolna struktura je bila raziskana na vzorcu 750 podočnikov. Izrazito večji delež samcev v skupini starejši� mladičev in napol odras-li� živali bi la�ko razložili z dejstvom, da je tudi pri današnji� medvedi� obdobje osamosvajanja bolj kritično za samce. Pri mlajši� odrasli� in zreli� odrasli� živali� je bila umrljivost verjetno večja pri samica�. Spolna struktura odrasli� medvedov, še posebej starejši� živali, kaže, da so Mokriško jamo kot zimski brlog večinoma zasedali samotarski samci.

Extinctions of Late Ice Age Cave Bears as a Result of Climate/Habitat Change and Large Carnivore Lion/Hyena/Wolf Predation Stress in Europe

“…Sophie's Cave has yielded few more wolf remains of wolf cubs in the material from the late Late Pleistocene layers, but also those are still too few for bone statistics. As with the lions and hyenas in the cave, the presence of wolves at least also indicates predation on cave bears (Figures 13(c) and 14(b)), and hence no "natural mortalities" can be expected in any European cave bear populations, as already mentioned [72]-this has only been suggested without taking into account the possibility of predation by carnivores [70,71]. During the Pleistocene wolves only used caves for cubraising, as in the present day [53,56,58].…”

“…It was generally suggested before that only "natural mortalities" occurred in those cave bear populations which were found in caves [70,71]. First interpretations of carnivore impact on cave bear populations were discussed in a single European cave [72].…”

Can morphospace shed light on cave bear spatial-temporal variation? Population dynamics of Ursus spelaeus from Romualdova pećina and Vindija, (Croatia)

“…Cave bear research has focused on material from Krapina (Miracle, 2007(Miracle, , 2011 and Vindija (Hofreiter et al, 2004;Withalm, 2005) although this represents a small percentage of available assemblages (Malez, 1963(Malez, , 1986Miracle, 1991;Miracle et al, 2010;Paunovi c, 1987Paunovi c, , 1988. The area could prove particularly fruitful for the study of population dynamics through comparative analysis with neighbouring regions that have undergone more extensive study such as Slovenia (Debeljak, 2004(Debeljak, , 2007Rabeder et al, 2004;Withalm, 2004a,b,c) and Italy (Argenti and Mazza, 2006;Capasso and Caramiello, 1999) as well as those further afield in Spain (Capasso, 1998;Estévez, 2004;Grandald'Anglade and Vidal Romaní, 1997;Pinto Llon et al, 2006;Torres et al, 2007) and France (Vercoutère et al, 2006;Bocherens et al, 2006).…”

Cave bear (Ursus spelaeus) from Chamber B of the Goyet Cave in Belgium

“…He argued that lower canine breadths in cave bears from cave sites of Mixnitz and Odessa were bimodal with modes at 16 17 mm and 2122 mm, and with a little overlap between these distributions. Debeljak (2004Debeljak ( , 2007 also obtained for Potoèka zijalka and Mokrika jama in Slovenia a bimodal distribution of upper and lower canine breadths and on the basis of this distribution classified specimens smaller than 18 mm as female and those larger than 18.5 mm as male. Canines from the Krapina rockshelter in Croatia were attributed to males, having breadth greater than 17 mm and length greater than 23 mm (Miracle, 2011).…”