Sunday 30 April 2017

Middle Spotted Woodpecker nesting in the Karst!

After the return from the Danube delta we can now enjoy in our favourite environment: the forest! This time of year is particularly busy for the woodland inhabitants, especially woodpeckers. In this post we'd like to share some exciting moments we've witnessed recently at our local patch on the Slovenian Karst, just a few minutes drive from our home.
Since 2015 we've been working on the occurrence of Middle Spotted Woodpeckers Dendrocopos medius in the Karstic region and right now a paper on the species is about to be published. In the last years, we carried out censuses in suitable karstic woods, where this rare oak-tree specialist might be present (see here & here). So far we have only found probable signs of nesting... until a few days ago, when we finally confirmed the nesting of this species in the Karst with the most obvious sign: an active nest-hole!
The activity in and around the nest is frantic, with the parents going in and out of the hole, delivering beakfulls of caterpillars to their chicks...
Despite being an oak-tree specialist, Middle Spotted Woodpecker doesn't always excavate nest-holes in oak, but prefers other soft-wood trees. In fact the choice of a nesting tree is dictated mainly by the state of wood decay, rather than the actual tree species. Having a quite weak bill, Middle Spotted likes to excavate in rotten wood, frequently close to some tree fungi (like Polypores), where the timber is even softer. 
In our case, the nest is located on a rotten branch of a beech Fagus sylvatica in a woodland of sessile oaks Quercus petraea. The hole is about 4-5 meters above the ground. In the first photo below two other larger holes are visible - those most probably belonged to Great Spotted Woodpecker.
In the next photos, note the characteristic erected red feathers on the head of the male (first two pics). Males have brighter crown feathers than females and when erected, they tend to be more conspicuous. The head colour can be easily compared when seeing both sexes together, such in the case of a nesting pair. Moreover when males approach the nest, they tend to erect the crown feathers as a sign of display. If you compare the sexes in all the photos, you will see that the female tends to have a more "gentle" look and not so bright red crown feathers. Note also the facial expression of the bird looking out from the hole (3rd photo below) - it is quite unlike any other woodpecker as it lacks moustachial stripes and the face looks quite plain.
When observing the nesting pair we payed attention not to disturb them and watched from a safe distance. Nevertheless the pair seemed very concentrated in bringing the greatest possible amount of food to the chicks and didn't bother our presence (short VIDEO). Middle Spotted Woodpeckers find their food mostly by gleaning and search the oak bark for small invertebrates and their larvae. At this time of year the main food brought to the chicks are caterpillars found in the tree canopies, but also other small insects (see pics below). In this respect Middle Spots are a bit like Blue Tits Cyanistes caeruleus or other Parus species that need to coincide their breeding with the greatest prey availability - that is, when the new green leaves are full of caterpillars.
The frentic activity of feeding the chicks should continue for at least a week, so we'll keep checking the status of the brood in the coming days.
Meanwhile the forest around the nest is alive with many other species. A Grey-headed Woodpecker Picus canus is "disturbing" the Middle Spots, drumming a few meters away from their tree and a Black Woodpecker Dryocopus martius should also be nesting somewhere in the same wood, together with a pair of Green Woodpeckers Picus viridis. And two more occupied cavities were found not far away...
A female Lesser Spotted Woodpecker Dendrocopos minor is looking out of her nesting hole. Note the tiny beak of the species, not really woodpecker-like. In fact its feeding technique is more similar to that of tit Parus species rather than that of other woodpeckers. But despite this, Lesser Spots still need to build the nest to rise up the chicks and usually every year a new hole is excavated.

Great Spotted Woodpecker Dendrocopos major has a more poweful beak and usually excavates several new nesting holes every year. Here it chose to do so in a rotten beech Fagus sylvatica - such trees have softer wood and in general are preferred by most woodpeckers.

The Karst's woodlands now also resound with the trills of migrating Wood Warblers Phylloscopus sibilatrix and with the songs of Cuckoos Cuculus canorus, while on the ground, some amazing flowers are in full bloom...
Paeonia officinalis with flowers as large as fists!
Rhagium mordax (Cerambycidae) feeding on Paeonia's nectar.
Ophrys insectifera - rather rare on the Karst, but we have it "in the backyard"!
Cephalanthera longifolia - a common woodland orchid.
Orchis purpurea - like woodland edges and sunny open woods.

At the end a note is necessary: all the above woodpecker's holes were found exclusively by Sara, whose primary interest this spring seems to be nest-hole finding! ;-)