Terrestrial invertebrates - Udine Cultura

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Similar to the cormorant, but smaller, is the pygmy cormorant (Phalacrocorax
pygmaeus). The most recent data indicate at least 150-200 pairs, which makes
the northern Adriatic fish-farms the most important breeding site in Italy for this
rare species.
The greater flamingo (Phoenicopterus roseus), a species considered extremely
rare in past decades, has increased rapidly, to some thousands of individuals in
the Po Delta and Lagoon of Venice, where the first cases of nesting were
recorded in 2007. This increase may be due to the success of the colonies in
central-southern Italy, or to a different migration strategy adopted by the
species as a result of climate change. The flamingo’s particular method of
feeding, filtering the top centimetres of sediment through its beak, make it
particularly susceptible to lead poisoning caused by the ingestion of shot
contained in cartridges fired by hunters. In recent winters, lead poisoning has
caused the death of dozens of birds in the Po Delta - dramatic evidence of this
problem, which has often been ignored.
The waders found on fish-farms include all those listed previously (grey plover,
curlew, dunlin, golden plover, avocet, black-winged stilt), together with others
more associated with farmland, like the lapwing (Vanellus vanellus), which has
also been nesting for some years, or freshwater environments, like the
common sandpiper (Actitis hypoleucos) and the snipe (Gallinago gallinago). As
well as the lapwing, surveys conducted in 2000-2002 have estimated the
Snipe (Gallinago gallinago)
presence in fish-farming ponds of 300-
400 pairs of black-winged stilt, 150-
200 of redshank, 80-100 of avocet and
a few dozen pairs of Kentish plover.
Also worth mentioning is the recent
nesting of the rare collared pratincole
(Glareola pratincola), present only in
one fish-farming pond of the Po Delta.
There are also various species of terns
which nest on sandbanks, islets and
embankments within the fish-farms:
almost 1000 estimated pairs of common
tern, 600 of little tern and up to 200 pairs
of gull-billed tern (Gelochelidon nilotica).
The last is the tern least linked to the
presence of water, often hunting
invertebrates and small terrestrial
Grey heron (Ardea cinerea)
vertebrates on farmland.
Among the larids, the most common is the herring gull (Larus argentatus),
which is particularly common in fish-farms of the Lagoon of Grado-Marano
and the northern Lagoon of Venice. Much less abundant as nesters are the
Mediterranean gull and black-headed gull.
Of great importance in the fish-farms are heronries, mixed breeding colonies
of ardeids, on trees, rows of tamarisks or reed-beds, mainly the little egret
(Egretta garzetta), grey heron (Ardea cinerea), red heron, great white egret
(Casmerodius albus) and squacco heron (Nycticorax nycticorax), but in some
cases accompanied by other colonial birds like the cormorant and pygmy
cormorant.
Some heronries, especially the largest ones, which may contain up to 800-1000
nests and have been occupied uninterruptedly for decades; others are more
ephemeral. Within a heronry, the distribution of the various species tends to
follow a set pattern: the red heron prefers to build its nest in a reed-bed or on
shrubs and small trees, while the grey heron sites its nest on the tops of
medium-tall trees. The squacco heron, little egret and the other species occupy
intermediate positions.
There are also reed-beds in the fish-farms, sometimes very extensive closest to
the freshwater channels. The bird fauna is that typical of the reed-beds
described above, plus the certainty of the presence of some pairs of bitterns,
one of the rarest birds in Italy.
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