Thursday 19 March 2020

Spring in the Karst & Škocjanski zatok

Despite the general virus situation, our field work still continues undisturbed (for now). This week we carried out several bird censuses and we've been out listening for Eagle Owl Bubo bubo almost every evening. The main news we were anticipanting you in one of the previous posts is this: - a live camera on the nest of "our" local Eagle Owls. We've been following this pair every spring since at least five years, within the "Eagle Owl Guardians" initiative launched by DOPPS-BirdLife Slovenia. It's the first time that a live camera is used on a bird's nest in Slovenia and it will give us a precious insight into the breeding biology of this rare and difficult-to-see night predator. In the past weeks our colleagues have also managed to catch and radio-tag 8 Eagle Owls in southwestern Slovenia. The results they are getting from the recovered data are giving an even better understanding of the breeding territories and movement of birds, helping directly in their conservation. At the moment the greatest cause of mortality in Eagle Owls is electrocution by medium voltage lines. This problem can be solved by isolating the dangerous parts of electricity poles - an operation that is taking place right now over most of the medium voltage lines in the Karst. More about the project can be found on this website, (only in Slovenian and Croatian).
Eagle Owl Bubo bubo on the nest in the Karst (live camera print screens).

Like every March, some days ago we began with our tradtional spring census of Middle Spotted Woodpecker Dendrocopos medius in the Karst area. This year we wanted to concentrate in areas of extreme western and southwestern Slovenia, where the species hasn't been recorded yet. At the moment we confirmed two new territories in the Komen Karst, in small isolated patches of old oak woodland. In the coming two weeks (time and virus permitting) we also have the intention to investigate the Slovenian Istria and the Goriška region.
Middle Spotted Woodpecker Dendrocopos medius, Komen Karst.

In recent days we also visited the limestone cliffs of the Karst edge between Osp and Hrastovlje, where the main entertainment was provided by a pair of Peregrines Falco peregrinus. They were establishing a territory, calling loudly and were even observed copulating. In the same cliff was also a small colony of Jackdaws Corvus monedula, one of very few colonies nesting in a natural cliff site. Crag Martins Ptyonoprogne rupestris have all returned to their breeding areas and were commonly observed along the cliffs. In the undergrowth, among other spring flowers were also the first orchids of the season - Early Spider Orchids Ophrys sphegodes.
Peregrine Falco peregrinus, Karst edge.
Jackdaw Corvus monedula, Karst edge.
A typical limestone cliff of the Karst edge.
Early Spider Orchid Ophrys sphegodes, Karst edge.
"Pale Birthwort" Aristolochia pallida, Karst edge.
Montpellier Maple Acer monspessulanum, Karst edge.

Now a change of habitat but still remaining in the Karst. The river Reka near Škocjanske jame (Škocjan caves) is one of the rare examples of groundwater on the otherwise dry limestone Karst. It is one of the very few places in our area where Dippers Cinclus cinclus can find the ideal habitat for breeding. During a recent visit we observed two different pairs, one busy constructing a new nest in a cliff above the river.
Dipper Cinclus cinclus, river Reka.

Supporting cast on the river Reka included several pairs of Grey Wagtials Motacilla cinerea, a Kingfisher Alcedo atthis (another very rare species in the Karst), a territorial Goshawk Accipiter gentilis and more Crag Martins Ptyonoprogne rupestris. The wet forest floor close to the river is particularly fertile and supports a lush early-spring flora. The most interesting plant is certainly the Toothworth Lathraea squamaria, an odd parasite found under deciduous trees, widespread in Slovenia, but only locally common.
Toothwort Lathraea squamaria, river Reka.
Alpine Squill Scilla bifolia, river Reka.
Rue-leaved Isopyrum Isopyrum thalictroides, river Reka.
Dog's-tooth Violet Erythronium dens-canis, river Reka.
Ramsons Allium ursinum, river Reka.
Scarlet Elf Cup Sarcoscypha austriaca, river Reka.

Otherwise there's a full range of other wildlife awakening/emerging/flowering in the Karst at the moment, including the first Mountain Pasqueflowers Pulsatilla montana in bloom on dry grasslands, mating amphibians in ponds, reptiles sunbathing on limestone rocks and a variety of birds already busy with breeding. In these first warm sunny days of the year, several freshly-emerged butterflies are finally on the wings including Wall Brown Lasiommata megera, Holly Blue Celastrina argiolus, Scarce Swallowtail Iphiclides podalirius and the lovely Orange-tip Anthocharis cardamines.
Cirl Bunting Emberiza cirlus, Komen Karst.
Mountain Pasqueflower Pulsatilla montana, Komen Karst.
Tommasini's Cinquefoil Potentilla tommasiniana, Komen Karst.
European Green Lizard Lacerta viridis (juvenile), Karst.
Agile Frog Rana dalmatina, Vipava valley.
Holly Blue Celastrina argiolus, Karst.
Serin Serinus serinus from our bedroom window, Karst.

Meanwhile Škocjanski zatok NR has closed its doors to the public because of the virus. Since the creation of the new visitor center and infrastructure a few years ago, the area is often under pressure by crowds of people walking their dogs or doing all sorts of recreational activities. Sadly most of such "visitors" have no real interest in nature whatsoever. Now that the reserve is closed to the public, wildlife is certainly benefitting from an almost complete absence of disturbance. Yesterday we carried out the weekly bird monitoring of the area in absolute peace and tranquility. We were amazed by how many birds were present in the freshwater wetland, along the main path around the reserve. In just a couple of days from the closure, the wetland was alive with migrant waterbirds, which are often shy on migration and need undisturbed wetlands. It was quite a long time since we experienced such a variety of species and numbers. In the freshwater marsh we were immediately greeted by a Spotted Crake Porzana porzana walking on the path. Shortly afterwards a male Little Crake Porzana parva performed brilliantly in front of one of the main hides. After a whole winter with just fleeting glimpses of Bittern Botaurus stellaris, we now finally managed to get long views of a bird that was trying to swallow a giant Marsh Frog Pelophylax ridibundus, while a Marsh Harrier Circus aeruginosus was mobbing it from above (see below). New spring arrivals at the reserve included 2 Spoonbills Platalea leucorodia, about 12 Black-winged Stilts Himantopus himantopus, 3 Little Ringed Plovers Charadrius dubius and 7 Garganeys Anas querquedula. In the brackish lagoon up to 30 Redshanks Tringa totanus were helding territories, while small flocks of Ruffs Philomachus pugnax and Snipes Gallinago gallinago were feeding in the mudflats along with Avocet Recurvirostra avosetta and Shelducks Tadorna tadorna. At least two pairs of courting Great Crested Grebes Podiceps cristatus were also present in the lagoon. Other more or less resident birds at the reserve in this period include small numbers of Pygmy Cormorants Phalacrocorax pygmeus and Cattle Egrets Bubulcus ibis, while one or two Sardinian Warblers Sylvia melanocephala were recently heard in the Spartium bushes (a possible future breeding bird at the reserve?). In the freshwater ponds close to the visitor center it's good to see again small numbers of Smooth Newts Lissotriton vulgaris, as well as the large Italian Crested Newts Triturus carnifex, swimming along the impressive water beetle Cybister lateralimarginalis and the odd Grass Snake Natrix natrix. In the bushes around the freshwater wetland Tree Frog Hyla arborea is commonly heard (although rarely seen), while Italian Wall Lizard Podarcis sicula can be seen on the circular path.
Spotted Crake Porzana porzana, Škocjanski zatok NR.
Little Crake Porzana parva, Škocjanski zatok NR.
Bittern Botaurus stellaris, Škocjanski zatok NR.
Bittern Botaurus stellaris in a threatening posture (with a frog in its beak) against a Marsh Harrier!

Black-winged Stilt Himantopus himantopus, Škocjanski zatok NR.
Great Crested Grebe Podiceps cristatus, Škocjanski zatok NR.
Italian Crested Newt Triturus carnifex (the large one) & 
 Smooth Newt Lissotriton vulgaris (the small ones), Škocjanski zatok NR.
Water beetle Cybister lateralimarginalis, Škocjanski zatok NR.
Italian Wall Lizard Podarcis sicula, Škocjanski zatok NR.