Origin and development of the mammalian fauna of the Julian Alps

Abstract

BIOGEOGHAPHIA — vol. XIII — 1987 Bingeografia delle Alpi Sud—OrIentaIi Origin and development of the mammalian fauna of the Julian Alps BORIS KRYSTUFEK Nzztzmzl History Museum of 51011671221, L/ztbljmzcz SUMMARY In the Wfirm the Julian Alps (hereinafter JA) were almost entirely covered \vith a thick sheet of ice. In the Boreal at the latest, i.e. 9000 years ago, the climatic conditions in the JA became similar to those of the present day. Thus it seems that the recent mammalian fauna of the JA consists mostly of species that made their way to this territory only as late as the post-Glacial, i.e. less than 10.000 years ago. At present the JA are populated by 24 species of insectivores, rodents and lagomorphs, which is not a small number in comparison with the 25 species living in the entire Alpine region of Yugoslavia. The only glacial relict is Lepm timzkizzr, whereas the remaining species are post-Pleistocene arrivals. Of greatest importance in the colonization of the JA was the refuge to the south of the ice-bound territory, Two characteristic species which invaded the IA and the northwestern Dinaric Alps from this refuge were C/aiolzomys m'1)alir and Pitymyr Iiec/Jtenstei/zi. The post—Pleistocene arrivals from the east (e.g. Pitymyr rubterrmzezts) as well as the late post-Pleistocene invaders (e.g. Apodemur agrzzrizzr, Microzzzys mz’/zz/Iu.r) no longer exerted an influence upon the formation of the recent JA fauna. The last group is represented by sinanthropic species which in the JA colonized human settlements (Rartizr, Mus) and cultivated areas i.e. fields, meadows and pastures. INTRODUCTION The Julian Alps (hereinafter JA) represent the southwesternmost part of the Alpine mountain mass. In the Pleistocene the region of the present Alps was the greatest southern uninterrupted ice—bound territory. Thus also in the Wurm the JA were almost entirely covered with a thick sheet of ice and were mainly devoid of fauna. However, in the glaciations themselves smaller areas in the ice—bound region were populated by mammals of northern origin (spe- cies of the tundra and the taiga). Most of the fauna presently populating this territory nevertheless found a refuge in the non—iced territory to the south of the present Alps. An important refuge of this type was also in the hills and the lowlands of northwestern Yugoslavia. As documented (Rakovec 1975), already in the Wurm this territory was populated by a number of mammalian species now living here as well as in the JA: Sorex 77zz'mItzIs, S. czmizeus, S. ozlpzmts, Croczdztra sp., Tczlpoz emopczezz, Muscardinm czzzellmzczrius, Glis glzlt, CZez‘brz'07z0mys glczreolzts, Microtus czrwzlis, M. agrestis, C/aionomys m'voz[z's, Pity- mys sp. (subtemmeus group) and Lepus europaeus. This fauna undoubtedly formed a base which in the Holocene again populated the JA once the gla- 845