Una serie di cache dedicata alle specie di uccelli che più frequentemente si possono osservare nella Riserva Naturale Pian di Spagna-Lago di Mezzola.
La Riserva, istituita nel 1985, è sito di interesse comunitario (SIC) ed è una delle zone di sosta degli uccelli migratori più importanti d'Europa; a sud dell’arco alpino ne sono rimaste soltanto quattro (le altre tre sono le Bolle di Magadino in Canton Ticino, le torbiere del Lago d’Iseo e i Laghi della Brianza).
Essa si trova lungo uno dei corridoi più brevi per l’attraversamento delle Alpi, quello che passa dallo Spluga.
Il lago di Como circa 2000 anni fa si estendeva verso la Valchiavenna fino a Samolaco; a seguito dei depositi dell’Adda e delle alluvioni del 1600 si formò un’area paludosa che divise il lago in due parti formando a nord il lago di Mezzola; l’aspetto attuale è quello che deriva dall’opera di canalizzazione dell’Adda da parte degli austriaci nel 1858.
Per qualsiasi informazione sulla Riserva Naturale consultate il sito www.piandispagna.it
Forse non tutti sanno che nella Riserva, oltre all’osservazione degli uccelli si possono effettuare bellissime pedalate e passeggiate lungo i percorsi segnalati. Questa serie di cache è stata approntata proprio per suggerire una visita a questi luoghi magnifici.
Le cache sono posizionate in zone liberamente accessibili senza il bisogno di uscire dai percorsi segnalati. Alcune di esse sono al di fuori del perimetro vero e proprio della Riserva.
La Bigiarella (Sylvia curruca Linnaeus, 1758), è un uccello della famiglia Sylviidae, che vive nelle regioni a Nord dell'equatore, di Africa, Asia ed Europa.
Sistematica
Ne sono conosciute sei sottospecie:
-Sylvia curruca blythi
-Sylvia curruca caucasica
-Sylvia curruca curruca
-Sylvia curruca halimodendri
-Sylvia curruca jaxartica
-Sylvia curruca telengitica
Fonte: "Sylvia curruca." Wikipedia, L'enciclopedia libera. 10 gen 2016, 11:25 UTC. 22 feb 2017, 16:22 <//it.wikipedia.org/w/index.php?title=Sylvia_curruca&oldid=77978361>.
A series of caches dedicated to the species of birds that can be observed more frequently in the Natural Reserve of Pian di Spagna-Lake Mezzola.
The Reserve was established in 1985. It's a Site of Community Interest and is one of the most important stopover areas for migratory birds of Europe; in the south of the Alps there are only four left (the other three are: the Bolle di Magadino in Canton Ticino; the peat bogs of Lake Iseo; the Brianza lakes).
It is located along one of the shorter corridors for crossing of the Alps, the one that passes through Splugen Pass.
Lake Como, about 2,000 years ago stretched towards Chiavenna to Samolaco; as a result of deposits of the Adda and the floods of XVII century it was formed a marshy area that divided the lake into two parts, forming the northern Lake Mezzola; the current appearance is what comes from the work of channeling Adda by the Austrians in 1858.
For any further information please visit the Natural Reserve website www.piandispagna.it
Perhaps not everybody knows that in the Reserve, in addition to the observation of birds it is possible to make beautiful bike and walk trails. This series of caches was prepared precisely to suggest a visit to these magnificent places.
The caches are placed in areas freely accessible. It is recommended not to leave the marked trails. Some caches are hidden outside of the Reserve area.
The Lesser whitethroat (Sylvia curruca) is a common and widespread typical warbler which breeds in temperate Europe, except the southwest, and in western and central Asia. This small passerine bird is strongly migratory, wintering in Africa just south of the Sahara, Arabia and India.
Unlike many typical warblers, the sexes are almost identical. This is a small species with a grey back, whitish underparts, a grey head with a darker "bandit mask" through the eyes and a white throat. It is slightly smaller than the whitethroat, and lacks the chestnut wings and uniform head-face color of that species. The lesser whitethroat's song is a fast and rattling sequence of tet or che calls, quite different from the whitethroat's scolding song.
Like most "warblers", it is insectivorous, but will also take berries and other soft fruit. This is a bird of fairly open country and cultivation, with large bushes for nesting and some trees. The nest is built in low shrub or brambles, and 3–7 eggs are laid.
Taxonomy
This species was first described by Carl Linnaeus in his 1758 edition of Systema Naturae, from a specimen collected in southern Sweden. The genus name is from Modern Latin silvia, a woodland sprite, related to silva, a wood. The specific curruca is a Latin term for a bird mentioned by Juvenal.
This species has been commonly assumed to be closely related to the whitethroat, as their common names imply. It was suggested that the two species separated in the last ice age similar to the pattern found in the chiffchaff and willow warbler, with their ancestor being forced into two enclaves, one in the southeast and one in the southwest of Europe. When the ice sheets retreated, the two forms supposedly no longer recognised each other as the same species. However, scientists researching this question have for quite some time realized that these two taxa are not particularly close relatives.
Rather, the lesser whitethroat and its closest relatives Hume's whitethroat and the small whitethroat appear more related to a group of morphologically quite dissimilar species. These vary much in size and color pattern, but also lack chestnut wing patches and have a strong contrast between the usually dark head sides and the white or whitish throat. The latter group occurs from the southern parts of the lesser whitethroat complex' range into Africa and include the Orphean warbler group, the Arabian warbler, and the brown and Yemen warblers sometimes placed in Parisoma. Thus, it rather appears as if the divergence of the lesser whitethroat complex and its closest living relatives is more ancient than assumed, and that it did not involve separation by ice sheets building up in Europe, but by aridification of the Arabian region (which also occurred throughout the Ice Ages).
The lesser whitethroat complex has been split up into the present species, Hume's whitethroat, and the small whitethroat from which the Margelanic whitethroat may also be specifically distinct. In this superspecies, the lesser whitethroat seems to form the basal European lineage. Only two subspecies are nowadays unequivocally recognized for the lesser whitethroat, and they intergrade throughout Central Europe:
-Sylvia curruca curruca – Western lesser whitethroat – western parts of range
-Sylvia curruca blythi – Northeastern lesser whitethroat – eastern parts of range. Has somewhat paler top of head, separated from face sides by white supercilium.
Two more taxa occur in the intergradation zone with the small whitethroat, stretching from the northern Caspian Sea area into Mongolia. The phylogeny of these is not well-researched, and they might eventually turn out to belong to either species or be stereotyped hybrids:
-Sylvia curruca/minula halimodendri
-Sylvia curruca/minula telengitica
Similarly, Sylvia curruca caucasica is intermediate between the lesser and Hume's whitethroats.
A bird which wintered at Landsort Bird Observatory, Sweden, differed in the analyzed mtDNA sequences from all known taxa in the complex, although it most closely resembled halimodendri in the field. As mtDNA is inherited from the mother only, were this bird a hybrid this should have been recognizable.
Source: Wikipedia contributors. "Lesser whitethroat." Wikipedia, The Free Encyclopedia. Wikipedia, The Free Encyclopedia, 23 Dec. 2016. Web. 22 Feb. 2017.
