Monday 9 March 2020

Early spring in Notranjska & Karst

After months of wintertime misery, spring is finally advancing, bringing along exciting and wildlife-filled days in the field. We hope blog posts will be more frequent in the coming weeks and months, cause spring is here! Last weekend was particularly interesting as we spent some more time in the field, combining the Karst, the area of Trieste and the Notranjska region.
On Saturday we visited an interesting stream with small waterfalls and travertine formations in the flysch hills close to Trieste. The wet rocks around the waterfalls are home to a small population of the rare Maidenhair Fern Adiantum capillus-veneris. The species is present in the surroundings of Trieste with a few locations, as well as in the Slovenian Istria and locally in parts of western Slovenia. It is mostly found on wet sandstone rocks in the sub-Mediterranean region and is thus absent from the (limestone) Karst and most of continental Slovenia, with a few exceptions.
Maidenhair Fern Adiantum capillus-veneris growing under a waterfall near Trieste.

In the evening we went to check a territory of Eagle Owl Bubo bubo along the Karst edge. This was a site we didn't visit for some time, so we were glad to confirm the presence of a territorial male. The owl sang quite shortly, but intensively for a couple of minutes, sitting on the top of a pine tree. In the photos you can just make out the silhouette of the bird.
Eagle Owl Bubo bubo, Karst edge.

Despite the still cold northeasterly burja, on Sunday we visited lake Cerknica after several months (!) from our last visit, to look for some birds on the lake as well as early spring flowers in the forest. The first surprise of the day was a beautiful Black Stork Ciconia nigra above Razdrto, battling against the strong wind, but heading steadily eastwards. It is a quite early record for the species, as we usually start seeing them from late March onwards. However like several other summer migrants, Black Storks too are appearing earlier than usual, sometimes even overwintering in our region. This year we'll pay special attention to this rare forest bird, trying to narrow down the breeding areas of two pairs we regularly follow in western Slovenia.
Black Stork Ciconia nigra, Razdrto.

Upon arrival at lake Cerknica and scanning through the almost-empty body of water, we soon found the species we've been looking for: a pair of Smews Mergellus albellus. This attractive northern duck has become an increasingly scarce winter visitor in Slovenia and can be surprisingly hard to find in western Slovenia. Lake Cerknica used to host flocks of up to 10 or more birds in certain winters, but that doesn't seem to be the case anymore. The species is somehow more regular along the river Drava in the east of the country. Another interesting find was a pair of Goosanders Mergus merganser swimming nearby, a quite uncommon bird at lake Cerknica. A few other ducks were present including only one female Goldeneye Bucephala clangula, some Tufted Ducks Aythya fuligula, Pochards Aythya ferina and small numbers of Teal Anas crecca and Shoveler Anas clypeata. No sign of Garganeys Anas querquedula which should be around anytime soon. Among raptors we observed three Hen Harriers Circus cyaneus and two Goshawks Accipiter gentilis, but not the local White-tailed Eagles Haliaeetus albicilla.
Drake Smew Mergellus albellus, Cerknica lake.

But the highlight of the day awaited us on the farmland surrouding the lake. As we were driving on a dirt road close to Dolenje Jezero, Sara spotted a small and long white shape jumping in the grass. We stopped abruptly and soon were watching a beautiful Stoat Mustela erminea sporting a partly winter fur. With a bit of patience the animal came closer and we could watch it at close quarters for more than half an hour.
Stoat Mustela erminea, Cerknica lake. Video taken by Sara.

In the early afternoon the familiar, echoing sound of migrating Cranes Grus grus made us look up... and there they were: a group of 112 Cranes catching a thermal. After a few circles they started heading eastwards. You can never get tired of the sight and sound of migrating Cranes!
Crane Grus grus, Cerknica lake.
Two views over the karstic temporary lake of Cerknica (Cerkniško jezero).

The forest roads around lake Cerknica were full of vernal flowers, some just coming into bloom, others, like Christmas Roses Helleborus niger, already going over and turning pink. Given the early season and the cold weather of Notranjska it was quite surprising to see a great variety of species one would expect in early April. Even the most typical representatives of spring in the Dinaric forests, like Blue-eyed Mary Omphalodes verna were in bloom. Later in the afternoon we also stopped in the area of Postojna, where a wet meadow hosted a large patch of lovely Spring Snowflake Leucojum vernum.
Christmas Rose Helleborus niger, Javorniki mountains.
Blue-eyed Mary Omphalodes verna, Javorniki mountains.
Hacquetia Hacquetia epipactis, Nanoščica river.
Alpine Squill Helleborus niger, Nanoščica river.
Spring Crocus Crocus vernus ssp. albiflorus, Cerknica lake.
Hepatica Hepatica nobilis, Cerknica lake.
Dog's-tooth Violet Erythronium dens-canis, Karst.
Spring Snowflake Leucojum vernum