Sunday 23 May 2021

A month with Lilford's Woodpeckers

Although in spring we are involved in many different bird monitorings and projects, Domen's main study focus has remained the White-backed Woodpecker Dendrocopos leucotos ssp. lilfordi. In May we have been tracking down breeding pairs quite intensively and therefore we happened to be in the forests of Snežnik several times a week. Although our researches started quite early in the season (due to the early territoriality and breeding of the species), weather conditions this spring were (and somewhat still are) quite miserable. Countless days spent on Snežnik were cold, foggy and rainy, while in several areas of the upper altitudinal belt (1300-1400 m a.s.l.) snow lingered on the ground. It wasn't until the 18th of May that we experienced the first warm and sunny spring day on Snežnik, but more on that later. Now let's start chronologically, from the beginning. Around the very end of April and the beginning of May we spent a couple of consecutive days on the Snežnik plateau, trying to find occupied White-back's nests. As said, the weather was rather terrible and wandering the vastness of these heavily-karstified mountains, in search of Europe's most elusive woodpecker, seemed as hopeless as looking for a needle in a haystack! Fortunately there were also friends to help us in the quest and to them we send our sincere thanks! Make sure to check their post (in the link) regarding their mystic search for White-backs.

Lovely spring weather at the beginning of May on Mt. Snežnik.
Forest reserve in the habitat of White-backed Woodpecker.
Fresh feeding signs of White-backed Woodpeckers were commonly found, but locating a nesting hole was a completely different matter. In the forest reserve where we've been searching more intensively, every third tree was a dead one, covered in saproxylic fungi and therefore representing a potential nesting tree. Apart from Black Woodpecker Dryocopus martius inhabiting these forests in even lower densities than White-backs, no other species of woodpeckers live in such mountain forest reserves (Great Spotted and Grey-headed usually prefer commercial forests at lower altitudes). Still, tracking down the White-backs that produced these signs was far from easy!
Fresh feeding marks of White-backed Woodpecker
After hours of wandering we were occasionally greeted by the low "chip" of a White-backed last! If the sound was faint and coming somewhere from the ground, then it was a male, feeding on a rotten and usually semi-buried piece of timber. Such males were nice to watch, but when they decided to move on, they were nearly impossible to follow. Moreover individuals in "feeding mode" at the end of April were certainly not yet collecting food for their young. First we thought they might have been already incubating, but later we realised that for most White-backs, incubation this year began later than usual, probably because of the very cold spring temperatures which delayed breeding for a week or two. Females instead were usually feeding higher up on trees and sometimes even in the canopies.
White-backed Woodpecker Dendrocopos leucotos ssp. lilfordi, male feeding on the ground.
White-backed Woodpecker Dendrocopos leucotos ssp. lilfordi, female feeding in the trees.
During a "lovely" misty morning we went to check on the progress of the only White-back's nest we have been able to find a few weeks earlier (see post). It was the 5th of May and while all the other woodpeckers observed so far seemed to have no interest in breeding, this pair was very busy brooding the chicks. Weather conditions were certainly not optimal for watching the birds on the 12 metre-tall tree where the nest was located and even Paul complained about the cold! A stiff, wet southerly was blowing and although nasty, it was the only thing that enabled the forest to clear from the fog from time to time. This allowed us to take a few shots of the male coming to the nest - in the pics you can clearly see it carries a large beetle larva, a typical food item for White-backed Woodpecker.
Touty in the misty forest.
Female White-backed Woodpecker carrying food to the nest.
Male White-back carrying a beetle larva to the nest.
Regardless of the weather, spring is simply too important to stay inactive and sleep, so the birdlife in the forest was nevertheless lively. We were frequently amazed by the presence of both Tawny Strix aluco and Ural Owls Strix uralansis in tha same area - two species that are usually said to exclude each other regarding echological niche. Although Ural Owl is much more of a daily bird and therefore easily seen in early spring, Tawny still remains strictly nocturnal and daytime encounters are rare. Once for a change we were therefore happy to see the commoner species! Tengmalm's Owl Aegolius funereus which is also a nocturnal bird, can be regularly heard singing during the day in early spring and therefore we weren't very surprised when we heard one in a conifer stand.
Tawny Owl Strix aluco
Ural Owl Strix uralensis - male
Note the blood on the bill from its last meal.
Ural Owl Strix uralensis - female.
Forest owls this year are certainly benefitting from the huge numbers of Bank Voles Myodes glareolus noisily roaming around the leaf litter. These rodents are numbering in the millions and are certainly the commonest and most abundant forest animals, wherever beech Fagus sylvatica is the predominant species. Because of this Ural Owls are having an excellent breeding season and although these owls are normally more dependant upon Edible Dormouse Glis glis (emerging in June) for rearing their chicks, this year the abundant food supply enabled them to breed earlier. In fact most Ural Owl's nest are already empty, with some chicks that have left the cavities already weeks ago. Bank Voles are not only supplementing the forest food chain, but also spreading the rather dangerous hantavirus, a quite serious illness affecting the kidneys. Due to this virus around 100 people have been already hospitalized in Slovenia this year.
Bank Vole Myodes glareolus
Red Squirrel Sciurus vulgaris
Edible Dormouse Glis glis - probably a leftover from a not hungry Ural Owl chick.
Red Deer Cervus elaphus
Claw marks of Brown Bear Ursus arctos on a log crossing a path.

The thick, persistent fog, rolling in from the Kvarner gulf (in nearby Croatia) and keeping mount Snežnik constantly in the clouds, also brought many summer migrants to the ground. At the beginning of May we witnessed a little fall of Pied Flycatchers Ficedula hypoleuca, as well as heard our first Golden Oriole Oriolus oriolus of the year. We couldn't see the oriole, this time not because of the thick foliage where the species usually hides, but because of the thick fog! The occasional and quite-unlikely species in this habitat was also Bee-eater Merops apiaster which we heard migrating overhead.
Pied Flycatcher Ficedula hypoleuca
At the beginning of May the forest floor around 1300 m looked still pretty dull with barely any spring flower in sight. The only exception was the occasional Hacquetia Hacquetia epipactis, Drooping Bittercress Cardamine enneaphyllos and Hepatica Hepatica nobilis. A bit better was on slightly lower elevations, where carpets of the beautiful Blue-eyed Mary Omphalodes verna were adorning the sunnier spots. This small plant with tiny blue flowers is such a characteristic species of the Dinaric mountains that it gave the name to the Dinaric beech-silver fir forest association Omphalodo-Fagetum. Near Postojna we also admired the attractive Henbane Bell Scopolia carniolica, another representative of the early spring in Slovenian forests.
Hacquetia Hacquetia epipactis
Henbane Bell Scopolia carniolica
Blue-eyed Mary Omphalodes verna
As the bad weather insisted on Snežnik, we decided to check also the nearby Javorniki mountains for any new White-back's territories. Although these forests are mostly commercial and lack in forest reserves with old-growth trees, we thought it was good to give it a try. Also this time we had some help from a colleague who found a territorial pair during a census. In the late afternoon on the 3rd of May we tracked down the pair and discovered it was excavating a nest-hole on a Sycamore Acer pseudoplatanus. It was a quite late date for nest-excavation, but a few days later, the pair was already incubating. When we visited again on the 21st of May, the chicks were born (probably only a few days earlier) and the parents were already busy feeding them.

White-backed Woodpecker Dendrocopos leucotos ssp. lilfordi, female in the Javorniki Mts.
White-backed Woodpecker Dendrocopos leucotos ssp. lilfordi, male at the second nest.
Nesting tree of the White-backed in the Javorniki Mts.

The Javorniki mountains form, together with the Snežnik's plateau, a large forested mountain-chain. Also here Ural Owls Strix uralensis reach important densities and the bird in the lower pic was spotted & photographed from the car, whilst we were driving on a forest road. When we stopped nearby we found another White-backed Woodpecker, but weren't able to confirm its breeding.
Ural Owl Strix uralensis from the car.
Mt. Snežnik (northern slopes) as seen from the Javorniki mountains.


In the second part of May, the weather started to improve also in the mountains and allowed at least 1-2 sunny days a week. During these days we took the chance and went looking for some more potential White-back's territories on Snežnik, where previously we couldn't find any nests. Driving up from the Reka valley to the Snežnik plateau was (once again) like going back in the season, but this time the difference wasn't so harsh as the beech trees on the plateau were already sprouting green leaves. One early morning around 05.30 we had a close encounter with our first Brown Bear Ursus arctos of the season - a young female, crossing the road in front of our car!

Misty morning in the Reka valley, from the slopes of the Snežnik plateau.
The wooded hills above the Reka valley.
Brown Bear Ursus arctos - young female.

An extensive search in a known White-backed Woodpecker's territory, where the pair eluded us on previous visits, finally produced its results. After following the male while it was collecting food and flying always in the same direction, we finally found its nest, most surprisingly, it was in a dead silver fir Abies alba. The lilfordi subspecies is known for its fidelity to beech as a nesting tree and cases of breeding in conifers are really rare. However, the commercial forest where the nest was found, is rather depleated in terms of dead standing trees and the birds didn't have much choice after all. A few years back the same pair nested in a rotten beech snag (the only one in the wider area) some 100 metres away from the current nest. The breeding phase of this pair was already advanced as both parents were constantly bringing food to the nest. The male usually delivered with an interval of 5-7 minutes, while the female only visiting a couple of times every hour. It was also interesting to note that the male usually brought single items which represented longhorn beetle larvae (Cerambycidae), collected on logs on the ground, while the female brought a mixture of invertebrates, mostly collected on tree branches.
Female White-back bringing multiple food items at once.
Male White-back with single food items.
Male White-back exiting the nest with faeces in the beak.
White-backed Woodpecker Dendrocopos leucotos ssp. lilfordi nesting in silver fir Abies alba.
White-back's nesting tree in a commercial forest.
The forest around the nest felt particularly springy, also because there was a gorgeous male Collared Flycatcher Ficedula albicollis singing in the canopies. Given the fact the species doesn't breed in this part of Slovenia, it is good to assume the bird was only a migrant, singing on its way east. A singing Golden Oriole Oriolus oriolus was also probably a migrant, as this species prefers thermophilous deciduous woodlands in the lowlands and hills, instead of mixed mountain forests. Occasionally Bee-eaters Merops apiaster migrating overhead were also heard and several migrant Spotted Flycatchers Muscicapa striata were also around. Supporting cast of common breeding birds included Mistle Thrush Turdus viscivorus, Treecreeper Certhia familiaris, Bullfinch Pyrrhula pyrrhula, Crossbill Loxia curvirostra, Dunnock Prunella modularis, Willow Tit Poecile montanus, Hawfinch Coccothraustes coccothraustes and several others.
Collared Flycatcher Ficedula albicollis
Crossbill Loxia curvirostra
Roe Deer Capreolus capreolus
May in the forests of Snežnik.
The great thing about the southernmost part of Snežnik's plateau is that you're never too far from the rocky mountain meadows extending from the edge of the forest. These meadows were traditionally grazed and now represent an excellent habitat for a high variety of birds, plants, butterflies and other wildlife. It's good to spend the central hours of the day on these meadows as several raptor species can be seen. We were lucky to spot a pair of Golden Eagles Aquila chrysaetos performing a display flight (nesting in the area), as well as migrant Red-footed Falcons Falco vespertinus and Montagu's Harriers Circus pygargus, plus common species such as Kestrel Falco tinnunculus, Common Buzzard Buteo buteo and Raven Corvus corax. Songbirds included Skylarks Alauda arvensis and Tree Pipits Anthus trivialis, although the meadows, if worked properly could produce Rock Thrush Monticola saxatilis and even the now very rare Rock Partridge Alectoris graeca. The spring flora on these mountain meadows has yet to come alive, but some nice species like Trumpet Gentian Gentiana clusii and Trieste Gentian Gentiana verna ssp. tergestina were already in fine bloom. Needles to say, the panorama was amazing - southwards it was stretching over the Kvarner gulf in Croatia, with several of its islands just "at hand's reach", as well as the Velebit mountain chain in the far south. To the south-west the impressive mount Učka towering above the Istrian peninsula and to all other directions Slovenia - as far north as the Julian Alps.
Mountain meadows on the southern edge of the Snežnik plateau, with the Kvarner gulf in the distance.
Mt. Učka (right) and the Kvarner gulf (HR). In the middle the forested hills between Rijeka (HR) and Ilirska Bistrica (SLO).
The island of Cres in the Kvarner gulf (HR).
Kestrel Falco tinnunculus
Trumpet Gentian Gentiana clusii
Spring Gentian Gentiana verna in a cold dolina on the Snežnik plateau.
Spring colours in the Snežnik-Javorniki mountains.
Meadows and pastures on the southwestern edge of the Snežnik-Javorniki mountain range.
Lower down, where the slopes of the Snežnik-Javorniki descend towards the Pivka valley, an open agricultural landscape opens. The mixture of grazed stony grasslands and wet meadows creates an extremely rich biodiversity. Red-backed Shrike Lanius collurio and Barred Warbler Sylvia nisoria have their highest densities in Slovenia right in this area. Every second bush seems to hold a shrike and wherever there's a shrike in the High Karst, a Barred Warbler is never far away. This interesting silvid seems to often nest beside Red-backed Shrikes, for protection from potential predators. And where there are many shrikes, there are thousands of Field Crickets Gryllus campestris (their favourite food). Other birds found on these meadows include Short-toed Eagle Circaetus gallicus, Woodlark Lullula arborea, Tree Pipit Anthus pratensis, Wryneck Jynx torquilla and probably even breeding Wheatears Oenanthe oenanthe (pairs observed recently in late May). At this time of year several of the late-spring orchids are at large on the meadows, with Fly Orchid Ophrys insectifera being particularly abundant in this area, while Military Orchids Orchis militaris are just beginning to bloom. Late May is surely the best time of the year to enjoy these wildlife rich habitats!
Red-backed Shrike Lanius collurio
Barred Warbler Sylvia nisoria
Field Cricket Gryllus campestris
Brown Hare Lepus europaeus
Lady Orchid Orchis purpurea
Military Orchid Orchis militaris
Fly Orchid Ophrys insectifera