The Willow Warbler in Jura, France
Mentioning the name of the Willow Warbler, the first thing that comes to mind is often the difficulty of identifying this bird in nature, especially when you start enjoying ornithology. We will begin by dwelling on this aspect that could be described as "irritating" for the majority of novice ornithologists! This small passerine belongs indeed to a large family that includes many similar species. Thus, the current reaction of a person opening the leaf-warblers section in the "Guide Ornitho" ¹ is often this one: "but they are all the same, I would never be able to identify them in the field!! ". Certainly the first illustrated ornithological guides represented them rather badly but with the boards of the recent works, in particular of the excellent "Guide Ornitho" illustrating all the birds of Europe, we reached the paroxysm of bird drawing and this quality of work is difficulty to find for others continents.
How to identify the Willow Warbler?
Back to our leaf-warblers! Looking more closely (in guides and in nature), there are actually some differences between species. And although these may be difficult to assess because of the liveliness of these passerines, special attention will be paid to details of plumage to appreciate the subtleties in the length, hues and contrast of some parts of the bird. One of the biggest puzzles is the identification of the Willow Warbler and the Common Chiffchaff as their plumage is very similar and these two species are among the most common in the family.
To begin with, one of the best criteria for identification between these two leaf-warblers is the primary projection of the bird: the length difference between primary and tertiary remiges.
Willow Warbler. Photo by Robert Balestra. Observe the ratio between the remiges of the Willow Warbler: the length of the primaries corresponds to about 2/3 of the tertiary remiges.
Common Chiffchaff. Photo by Jonathan Guillot. The primary projection of the Common Chiffchaff is short and corresponds to about half of the tertiary remiges.
The Willow Warbler is a long-distance migratory bird wintering in sub-Saharan Africa. Its wings are proportionately longer than the Common Chiffchaff which winters mainly in Europe and North Africa.
Then, it will be necessary to focus on details and try to group a set of criteria such as the eyebrow, the hue of the legs and ear coverts, etc. These criteria, as a whole, remain difficult to assess in the field with birds constantly moving but these species are also good subjects to practice bird photography and having a good image will make identification certain.
Where to see the Willow Warbler in Jura, France ?
In the wild, leaf-warblers generaly occupy wooded habitats ². The Willow Warbler is a species that appreciates herbaceous and bushy strata and is typically found in shrubby forest recolonization areas. In Jura, France, the Willow Warbler is particularly abundant in altitude and especially in willow marshes and peat bogs ³.
How is the Willow Warbler currently doing in Franche-Comté, France ?
Like many long-distance migratory passerines, the Willow Warbler has declined in recent decades. The species faces the consequences of climate change and the modification of its wintering habitats ². However, in the Franche-Comté region numbers seem stable, probably due to relative preservation or even an increase in its breeding habitats ³.
In the Jura, we are lucky to have an important breeding population ³! Although this bird may not be the most photogenic of the region, it is a particularly interesting subject for photographers because it is quite challenging to put in the frame. In addition, this small ball of feathers of about ten grams which travels thousands of kilometers each year deserves a little attention :)
Join us for our wildlife photo tour in Jura, France to observe the Willow Warbler and discover many other species typical of the Jura mountains.
Emilien
Guide Salva Fauna
¹ Svensson L., Mullarney K. & Ztterström D. (2009). Le Guide Ornitho. Delachaux & Niestlé, Paris, 446 p.
² Issa N. & Muller Y. coord. (2015). Atlas des oiseaux de France métropolitaine. Nidification et présence hivernale. LPO /
SEOF / MNHN. Delachaux et Niestlé, Paris, 1 408 p.
³ LPO Franche-Comté (2017). Les oiseaux de Franche-Comté - Répartition, tendances et conservation. Biotopes éditions. 480 p.
