Although
the river Elsa is really never more than a substantial stream throughout
most of its length, it nevertheless forms the habitat of a number of interesting
animals species, vertebrate and invertebrate, that can be observed by
anyone following the walking trails through the
Val
d'Elsa. Among the
more interesting are:
Molluscs
The fresh-water mussel (Unio mancus), a bivalve mollusc, can grow as long as 10 cm and lives in the mud or in the sand of the river-bed.
U. mancus is edible.

Unio
mancus
Arthropods
The
river shrimp (Palaemonetes antennarius), a small crustacean which can reach lengths of
3 cm and which feeds on algae and aquatic plants.
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| Palaemonetes antennarius
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Potamon
fluviatile
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Another crustacean, this time much harder to find, is the river crab (Potamon
fluviatile), the carapace of which can be as wide as 10 cm. These
crabs differ from freshwater crabs found in Africa and Asia in that they
do not have to return to the sea to breed. As little as twenty years
ago, they were much more widespread in Italian rivers than they are now
but they are still to be seen both in and often out of the water in the upper
reaches of rivers, including in the seasonal torrents known as borri.
They vary considerably in colour between individuals and seasonally. The
nature park at
Valle del Treja near Rome
is another river crab habitat and they have been reported recently even
in the ancient Roman water ducts in central Rome.
Insects
A great many insects populate the river, and their larvae are even more
numerous. Among them are dragonflies, caddis flies and mayflies.

Italian
dragonfly species
Vertebrata
Many vertebrates also inhabit the the Elsa, and it is easy to come across some of them along the
banks and in the river.
Fish
The chub (Squalius cephalus, also known as Leuciscus cephalus) is the most common fish found in the
Elsa. There are great numbers of chub in this river (often mistaken by
non-fishermen for trout), along with barbel (Barbus sp.) and
carp (Cyprinus carpio), a fish which can grow up to 15 kg in weight in this area.
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| Barbus
barbus
(left) and Squalius cephalus
(right) |
Padogobius nigricans |
The Arno goby (Padogobius nigricans), a type of gudgeon known
locally as ghiozzo di ruscello, is the most unusual fish to be found in the
Elsa. Amphibians
In the streams and borri running into the Elsa and in the headwaters of
the Elsa itself, there is no shortage of amphibians, including the
Italian crested newt
(Triturus carnifex), which can be quite large (20 cm) and the spotted
newt (Triturus vulgaris). In summer, these are usually observed
resting on the bottom of pools of water.
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| Triturus carnifex
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Triturus vulgaris
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The common toad (Bufo bufo) is abundant and there are tree-frogs
(Hyla intermedia), the only tree-dwelling amphibian in Italy, as well as the
common green frog and the Italian jumping or agile frog (Rana latastei), so-called for its
capacity for prodigious leaps.
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|
Hyla intermedia
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Rana latastei |
Reptiles
During summer, two species of snake are commonly seen swimming. These
are the grass snake (Natrix natrix), also known as the ringed
snake from the characteristic yellow ring behind the head, and the Dice snake Natrix tessellata, both of which are
timid and completely harmless. The grass snake lives predominantly on
frogs and hence is so common near water that it is also called the water
snake. The Dice snake eats fish by preference. The common viper (Vipera berus) is
sometimes seen warming itself on rocks near the river. During winter,
all three species hibernate and are rarely seen.
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| Natrix natrix
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Natrix tessellata
eating a goby
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Birds
There are several species of riverine bird to be seen in the Val d'Elsa, drawn by the abundance of
nesting places and food, including a very fine species of grey heron (Ardea
cinerea), which has a wingspan of almost 2
m, and the Little egret (Egretta garzetta), which are seen only in the winter.
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| Ardea
cinerea
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Egretta garzetta
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One can also spot the wild duck (Anas platyrhynchos) and the moor-hen
(Gallinula chloropus), the wagtail (Motacilla cinerea), and finally the kingfisher
(Alcedo atthis), easily recognized by its bright plumage, which is blue-green on its back and orange underneath.
Alcedo atthis
Mammals
The only aquatic mammal present in the Elsa today is the nutria
or coypu (Myocastor coypus), a large, South American rodent imported into Italy after
WW II and raised for its fur. Nutria are around 50 cm long and became widespread as a result of floods
that destroyed the farms along a number of rivers where they were kept and bred, thereby releasing these animals into the wild.
They are now an invasive pest and in Italy during 1995-2000, for
example, despite control activities involving the removal of 220,000
nutria at a cost of over 2.5 million euros, damage to the riverbanks due
to burrowing exceeded 10 million euros value and impact on agriculture reached
about
1 million euros. These are observed mostly in the river with the nose,
eyes and a small amount of back showing. 
Myocastor
coypus There
is a wide range of terrestrial mammalian species in the woodlands
of the Val d'Elsa, including field mice, voles, several species of bat,
squirrels, hedgehogs, porcupines, martens, hare, various species of deer,
and wild boar. For pictures please refer to Tuscan
wildlife
and Bed
& Breakfast Il Cielo.
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