Being a mountainous country, Slovenia is very rich in cliff faces. Perhaps the most interesting are those formed in the karstic limestone. In the Karst region of western Slovenia there is a very clear geological line, known as Kraški rob or Karst edge, dividing the limestones of the Classic Karst from the coastal flysch area. The edge is actually a line of more or less continuous limestone cliffs, running in a northwest - southeast direction. The cliffs are usually vertical and are exposed to the sun and so enjoy a particularly warm microclimate, favouring several interesting plant and animal species. In this chapter we will mostly focus on the cliffs of the Karst edge as these are truly different from the ones encountered in the Alps and other regions of Slovenia and host the most interesting wildlife.
Rocky cliffs represent an important habitat for birds in Slovenia. Several endangered species breed on them as they are safe on such inaccessible sites. One of them is the Eagle Owl Bubo bubo which nests on sunny cliffs, steep rocky slopes or even in abandoned quarries. The Karst is an excellent habitat for this species and most of its Slovenian population is found right in the southwestern part of the country. There are more than 100 breeding pairs of Eagle Owl in Slovenia. Another charismatic raptor nesting on cliffs is the Peregrine Falcon Falco peregrinus, that usually avoids the Eagle Owl. The latter is a deadly predator of Peregrine chicks and even adult birds. Golden Eagles Aquila chrysaetos are thinly distributed across Slovenia and almost all breed on rocky cliffs. Several pairs do so in karstic areas of southwestern Slovenia, while a few others breed in the Alps.
Other interesting inhabitants on cliffs along the Karst edge include Alpine Swift Apus melba, Blue Rock Thrush Monticola solitarius, Rock Bunting Emberiza cia, Rock Dove Columba livia, Raven Corvus corax and, locally, also Crag Martin Ptyonoprogne rupestris. Slovenia’s few breeding pairs of Red-rumped Swallow Cecropis daurica also breed on karstic cliffs, close to the border with Croatia.
Outsite the breeding season, the Karst edge attracts wintering Wallcreepers Tichodroma muraria that move down from the Alps to warmer areas of western Slovenia. Similarly Alpine Accentors Prunella collaris also make such movements and can be observed in small flocks, patrolling the Karst edge in winter.
Of the other animals living on cliffs there is only space to mention a few reptiles here, including the Horn-nosed Viper Vipera ammodytes, the rare and elusive European Cat Snake Telescopus fallax, the common Dalmatian Algyroides Algyroides nigropunctatus and the Dalmatian Wall Lizard Podarcis melisellensis.
Eagle Owl Bubo bubo
Blue Rock Thrush Monticola solitarius
Rock Bunting Emberiza cia
Wallcreeper Tichodroma muraria (Photo: Dušan Klenovšek)
Alpine Swift Apus melba
Dalmatian Algyroides Algyroides nigropunctatus
Of the plants there are several interesting species that are found on karstic limestone cliffs. The endemic Tommasini's Sandwort Moehringia tommasinii only grows on a few sites along the Karst edge in Slovenia, Italy and Croatia. A very prominent plant, growing out from cliffs in summer is the tall Pyramidal Bellflower Campanula pyramidalis. Other interesting species include Common Sage Salvia officinalis, Hyssop Hyssopus officinalis, Winter Savory Satureja montana, Rocky Stonecrop Sedum rupestre, Common Houseleek Sempervivum tectorum, Grecian Foxglove Digitalis laevigata, Upright Woundwort Stachys recta, Yellow Germander Teucrium flavum, Buckler-mustard Biscutella laevigata, Alpine Daphne Daphne alpina, Centaurea cristata, Crepis chondrilloides, Frangula rupestris, Genista holopetala, Seseli gouanii, Onosma javorkae and Silene saxifraga. On a few north-facing cliffs in the Karst and on montane and alpine cliffs in central and northern Slovenia Bear’s-ear Primula auricula is a characteristic and beautiful species, adorning the limestone rocks in early spring.