Monday 20 April 2020

Overwhelming spring

The most exciting and wildlife-filled time of the year has arrived. The second half of April brings with it not only an increased activity of the resident wildlife, but also a wave of migratory birds, including rarities. Understandably our work has now shifted from "office" to "field" mode. We are very glad to say that most of our time is now spent outdoors doing bird censuses. Therefore trying to sum up all the interesting observations from the past two weeks in a single post can be a tough task. But we'll try. In the last two weeks our itineraries have remained mostly the same, as we've been commuting between our home area in the Karst around Sežana, Škocjanski zatok and the Karst edge. We have divided the post in two habitat sections:


One extremely interesting habitat at this time of year are dry karstic grasslands. We visited some fine examples of this precious ecosystem above the Karst edge (between Osp and Črni kal), while carrying out farmland bird censuses for DOPPS. The spring diversity of birds was overwhelming and included species such as Hoopoe Upupa epops, Wryneck Jynx torquilla, Nightingale Luscinia megarhynchos, Cuckoo Cuculus canorus, Turtle Dove Streptopelia turtur, Corn Bunting Emberiza calandra, Cirl Bunting Emberiza cirlus, Skylark Alauda arvensis & Woodlark Lullula arborea, Common Whitethroat Sylvia communis, Stonechat Saxicola torquatus, Linnet Linaria cannabina all singing their hearts out. A typical bird of this habitat is the Tawny Pipit Anthus campestris, a rare breeding bird in Slovenia, confined to the most stony and barren grasslands of the Karst. We were glad to see a pair back on the same territory as last year. In the sky a Short-toed Eagle Circaetus gallicus hovered above its breeding territory, while a noisy flock of 50 Alpine Swifts Apus melba was circling above their well-known colony.
Tawny Pipit Anthus campestris
Tawny Pipit habitat.
Short-toed Eagle Circaetus gallicus
Skylark Alauda arvensis
Common Whitethroat Sylvia communis
Linnet Linaria cannabina
Corn Bunting Emberiza calandra
Nightingale Luscinia megarhynchos
Cuckoo Cuculus canorus

A good passage of migrants resulted in the year's first Red-footed Falcon Falco vespertinus, a Black Kite Milvus migrans, a Hen Harrier Circus cyaneus, Tree Pipits Anthus trivialis going overhead, Whinchats Saxicola rubetra, Wood Warblers Phylloscopus sibilatrix and Garden Warbler Sylvia borin. However on the grasslands near Petrinje we came across two even more interesting migrants. First we saw two female Ring Ouzels Turdus torquatus, a scarce passage bird to the Karst, although a widespread breeder in the mountains above 1500 meters. Then whithin a flock of 10 Northern Wheathears Oenanthe oenanthe there was a really striking black-and-white bird: a stunning male Black-eared Wheatear Oenanthe hispanica of the black-throated form! This is a rare, but annual migrant to open areas of western Slovenia. It doesn't breed in our country, but further south in Croatia, so these spring sightings usually involve overshooting birds.
Black-eared Wheatear Oenanthe hispanica
Ring Ouzel Turdus torquatus
Northern Wheatear Oenanthe oenanthe
Whinchat Saxicola rubetra
Black Kite Milvus migrans

The dry stony grasslands provide habitat also to other wildlife, especially reptiles, which are the main food of the Short-toed Eagle. During our visits we came across the very common European Green Lizard Lacerta viridis, as well as a couple of Dalmatian Wall Lizards Podarcis melisellensis. The latter in Slovenia is only confined to the Karst. Although the real spectacle of blooming flowers on the dry grasslands is yet to come (mid May-early June), some wildlflowers were already putting on a good show.
European Green Lizard Lacerta viridis
Dalmatian Wall Lizard Podarcis melisellensis
Dry stony grassland.
Austrian Vipergrass Scorzonera austriaca
Green-winged Orchid Anacamptis morio
Argyrolobium Argyrolobium zanonii
Silvery Broom Genista sericea
Karstic pasture on limestone (with Istria in the background).
Manna Ash Fraxinus ornus
Dry karstic grassland above Osp, on the border with Italy, with Trieste
in the background and the village of Prebeneg in the foreground.
Karstic shrubland on the Karst edge, looking down towards Istria.
False Vetch Astragalus monspessulanus - likes sandstone rather than limestone,
hence commonly found in Istria and rarely in the Karst.

Birding around home in the Sežana area was also very productive recently. We have a pair of Short-toed Eagles Circaetus gallicus, nesting about 7 km in a straight line from our home and we even spotted the eagle above our garden once. We know the approximate area where they breed and have frequently seen the pair circling together and calling (watch the video below). A pair of Goshawks Accipiter gentilis is probably also breeding nearby.
Short-toed Eagle Circaetus gallicus (turn on the volume!)

Last week during a session of raptor watching we also had an Osprey Pandion haliaetus migrating eastwards not far from Sežana. This species is a regular migrant in Slovenia, but rather scarce in the western part and actually quite rare over the Karst. Nice birds in and around the garden recently also included Hoopoe Upupa epops, Nightingale Luscinia megarhynchos and Cuckoo Cuculus canorus, while Scops Owls Otus scops can be also heard at night. A Griffon Vulture Gyps fulvus was also seen on migration as were flocks of Alpine Swifts Apus melba and House Martins Delichon urbicum heading north. The dry meadows around home have also provided some interesting wildlife, especially in terms of plants like Narrow-leaved Fritillaries Fritillaria orientalis (F. tenella) which have incredibly small flowers this year, and the Illyrian endemic Trieste Spring Gentian Gentiana tergestina (aka G. verna ssp. tergestina), as well as many other commoner plants. The "wild asparagus collecting fever" is also in full swing, although the absence of rainfalls means the production of spring shoots is quite reduced this year.
Osprey Pandion haliaetus
Rock Bunting Emberiza cia
Raven Corvus corax
Mistle Thrush Turdus viscivorus
Narrow-leaved Fritillary Fritillaria orientalis (tenella)
Trieste Spring Gentian Gentiana (verna) tergestina
Green-winged Orchid Anacamptis morio
Mountain Pasqueflower Pulsatilla montana
Weaver's Fritillary Boloria dia
Amelanchier Amelanchier ovalis
Nice Milkwort Polygala nicaeensis
Dyer's Greenweed Genista tinctoria
Hairy Broom Chamaecytisus hirsutus
St. Lucie's Cherry Prunus mahaleb on a typical karstic griža (limestone heap).
Montpellier Maple Acer monspessulanum
Downy Oak Quercus pubescens
Hop-horbneam Ostrya carpinifolia
Wild Asparagus Asparagus acutifolius - spring's favourite wild food for people in the Karst & Istria.
Narrow-leaved Asparagus Asparagus tenuifolius
Overlooking a karstic dolina.
Hidder corner of the Karst around Sežana.


One of the places we also visit on a regular basis include the mixed oak-beech forests in the cooler parts of the Karst. Every year since 2014 we make regular observations of Ural Owl Strix uralensis in these forests, mostly outside of the breeding season. This year we wanted to get an idea about the spring presence of this rare species in western Slovenia, so we carried out an acoustic (playback) census. In one evening we recorded 3-4 birds, including a singing pair. It was interesting to note that where we had Ural Owl response there was also at least one aggressive Tawny Owl Strix aluco responding. It is otherwise known that the two species exclude each other because of predatory pressure by Ural on Tawny. Strange enough at the end of the evening we counted no less than 16 territorial Tawny Owls! Additional atmosphere to the night chorus was provided by some howling Golden Jackals Canis aureus that live in the area. Later we made several visits to the forest by day and at twilight and were rewarded with some close encounters with a female Ural Owl in one of the presumed breeding territories. We still don't know if the area is completely suitable for its breeding, as there are very few large trees with natural cavities or semi-cavities. Further investigation is needed.
Tawny Strix aluco singing & calling and Ural Owl Strix uralensis female barking 
(raise the volume to max).
Ural Owl Strix uralensis
Ural Owl habitat.

The mixed oak-beech forests at this time of year are also otherwise exciting. Returning Cuckoos Cuculus canorus sing in every valley and other birds are busy with breeding activities, while the forest canopies change to a beautiful light green colour. Migrant Wood Warblers Phylloscopus sibilatrix have appeared a few days ago as have Pied Flycatchers Ficedula hypoleuca. Both species like to stop in deciduous forests on their northward migration. On the other hand Collared Flycatcher Ficedula albicollis is a rare passage migrant to western Slovenia and we have never seen it in the Karst before... until a few days ago, when we came across a stunning male, calling high in the beech canopies. The species otherwise breeds commonly in lowland and hilly eastern Slovenia, but is virtually absent in the west. 
In the forest here and there we got the hear the occasional Middle Spotted Woodpecker Dendrocopos medius (mostly egg-laying at the moment), while the pair of Black Woodpeckers Dryocopus martius we have been following for a couple of years is nesting again in their old nest-hole.
Collared Flycatcher Ficedula albicollis
Pied Flycatcher Ficedula hypoleuca
Black Woodpecker Dryocopus martius - egg-laying shift (male going out, female going in).
Black Woodpecker Dryocopus martius - female at the nest-hole.
Black Woodpecker Dryocopus martius - male at the roost hole.
Middle Spotted Woodpecker Dendrocopos medius
Fire Salamander Salamandra salamandra
Water in the forest: a karstic spring, where salamanders larvae develop.
Southern Festoon Zerynthia polyxena - on the woodland's edge.
"Pale Birthwort" Aristolochia pallida - Southern Festoon's larval food-plant.
Mighty beech forests in the hills on the edge of the Karst.
Acidic oak woodland with Bilberry Vaccinium myrtillus in the undergrowth.
Bilberry Vaccinium myrtillus
Narrow-leaved Helleborine Cephalanthera longifolia
Sunset in the beech forest.