The Boreal Owl in Jura, France
The Boreal Owl is a species of nocturnal raptor found in large forest areas mainly in the mountains. Its range overlaps globally with that of the Eurasian Pygmy-owl which was the subject of a previous article (see the Eurasian Pygmy-owl in the Jura mountains). Like the latter and various mountain species difficult to observe, the Boreal Owl is very popular with birders. This owl nevertheless presents a higher difficulty: it has a mostly nocturnal activity, which makes it generally less easy to discovery than its cousin. With a little luck and a lot of perseverance, she can offer us the opportunity to observe it. His discovery is always a magical moment!
I met the Boreal Owl for the first time while birdwatching with friends in a large Jura forest in the spring of 2012. After only a few minutes of research, while we looked at some interesting trees and I told them explain why this or that tree was favorable to host a nest, we arrive in front of our second cavity tree: an especially favorable beech, with several lodges formerly dug by a Black Woodpecker (Dryocopus martius).
I make a quick check of each cavity with the binoculars when my friends hear me say “calmly”: "Boreal Owl !!". She was there, in front of us! The head slightly out of the hole of the cavity, she watched us peacefully. This species is commonly found under these conditions. Curious and unsuspecting, she shows up at the entrance of its cavity when it needs to check if a predator is not lurking. According to some authors³, it could also be placed in front of the entrance of the cavity to obstruct it at the sight of the predator, often a pine marten (Martes martes).
We took a few minutes to observe and photograph it, and we left quietly to avoid disturbing her further.
How to identify the Boreal Owl?
Unlike some other bird families or genera, nocturnal raptors are represented by a limited number of species in France and are relatively easy to differentiate. The Boreal Owl can hardly be confused with other birds except for the Eurasian Pygmy-owl, as they live in similar habitats.
The Boreal Owl is a small nocturnal raptor with a large head, a flat cap and white facial discs creating an "surprised" expression. It is a larger than the Eurasian Pygmy-owl. It has brown upper parts with whitish spots and diffuse pale spots on the shoulders. The underparts are whitish with diffuse brown specks. Its wings are rounded and its flight is direct and straight. On the contrary, the Eurasian Pygmy-owl has short wings and a wavy flight.
Where to see the Boreal Owl in the Jura?
The Boreal Owl is present throughout the Jura Mountains, mainly above 900-1000 m. It also breeds at lower altitudes, for example on the foothills of the first plateau of the Jura where birds are known at 450-600 m altitude.
The forests occupied by this little owl are similar to the breeding habitat of the Eurasian Pygmy-owl: beech-fir and mature beech forest². It often breeds in Black Woodpecker lodges usually carved out of beech trees, and to a lesser extent in Green Woodpeckers (Picus veridis) or in natural cavities.
Status of the species in Franche-Comté and Jura?
The number of Boreal Owls is directly related to the status of forest rodent populations that are dependent on beech fructifications. The Boreal Owl is well studied in the Swiss Jura³ and part of the Jura². An increase in numbers and an extension of its range has been observed in Europe as well as in Switzerland and France in the 1960s, but there has been a steady decline in densities over several decades, irrespective of large fluctuations in breeding populations ²,³.
This decrease in the population is as always, multifactorial:
climate change and competition for breeding sites and food resources with the Tawny Owl (Strix aluco);
climate change, which also plays a role in the availability of food resources;
the disappearance of old trees and more generally trees with cavities allowing nesting ²,³.
Our ethical wildlife tour in the French Jura is a great opportunity to observe the Boreal Owl and discover many other species typical of the Jura mountains.
Emilien
Guide Salva Fauna
References :
1 : Cabard P. & Chauvet B. (1998). Etymologie des noms d’oiseaux. Eveil Nature. 589 p.
2 : LPO Franche-Comté (2017). Les oiseaux de Franche-Comté - Répartition, tendances et conservation. Biotopes éditions. 480 p.
3 : Maumaury L. Valloton L. & Knaus P. (2007). Les oiseaux de Suisse. 848 p.
4 : Svensson L., Mullarney K. & Ztterström D (2010). Le Guide Ornitho. 446 p.
