Terrestrial invertebrates - Udine Cultura

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130 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. 131
132 Lesser white-toothed shrew (Crocidura suaveolens) ■ Mammals Among the various types of wetlands, transition environments host the most interesting communities of mammals. The reed-beds sustain vast populations of harvest mouse (Micromys minutus), widespread both in more internal freshwater areas and in more halophile ones. The greatest density of harvest mice is recorded in the thickest reed- beds, and only marginally in sparse ones mixed with other vegetation. The presence of Miller’s water shrew (Neomys anomalus) is also of great faunal interest: this swimming insectivore, which is closely linked with lagoonal environments, may be very abundant locally. Other recorded species are the common wood mouse (Apodemus sylvaticus) and the Udine shrew (Sorex arunchi), especially where pure reed-beds degrade towards situations with mixed riparian vegetation. In marginally halophilous or more degraded environments the lesser white-toothed shrew (Crocidura suaveolens) predominates. The principal characteristic that determines the high biodiversity of reed-beds is probably the link between this type of vegetation and the damp soil rich in organic matter in which insects abound - the main prey of many shrews. Small mammals in salty meadows are numerically limited but interesting, as these environments are periodically submerged by high tides and have loose silty soils - conditions that do not permit the building of nests and tunnels. The species to be found here are the lesser white-toothed shrew, common rat (Rattus norvegicus), house mouse (Mus domesticus) and, more rarely, the wood mouse, which occasionally visits these habitats to feed at low tide. The richest community of mammals is that of the dry environments bordering the wet areas (lagoon edges, fish-farms, agro-ecosystems) where there are grassy banks, uncultivated land, and clumps of shrubs and trees. Here, the dominant species are the house mouse and wood mouse, which may cohabit but which generally indicate two different environmental situations: the former, degraded situations or early stages of forested environments; the latter, the presence of more highly structured vegetation. Quantitatively, the third place is occupied by the ubiquitous lesser white-toothed shrew. A series of minor species follow, including the harvest mouse and water shrew in marginal reed-beds, and the Udine shrew which frequents wooded areas. The northern water vole (Arvicola terrestris) is well-adapted to amphibian life and inhabits oxbow lakes and channels, even small ones, as long as there is abundant grass cover on the shores. Then there is the field fauna: some species of grass voles (Microtus savii, M. arvalis and M. liechtensteini) and the very common northern mole (Talpa europaea). The bicoloured white- Weasel (Mustela nivalis) toothed shrew (Crocidura leucodon), the tiny pygmy white-toothed shrew (Suncus etruscus), striped field mouse (Apodemus agrarius) and ship rat (Rattus rattus) are more localised. Among medium-sized mammals, the hedgehog (Erinaceus europaeus) is common. Just one lagomorph, the brown hare (Lepus europaeus), is quite widespread. Two other species, neither of them native, are present to a very localised extent: the rabbit (Oryctolagus cuniculus) and the eastern cottontail (Silvilagus floridanus), the latter a native of North America. The coypu (Myocastor coypus), a large rodent of South American origin, whose populations originated from repeated escapes and releases from fur farms, is now very common and at times invasive, especially in the Po Delta and Lagoon of Venice. Five species of carnivores are known in the lagoon fish-farms, especially where there are embankments and hummocks covered in abundant vegetation: the red fox (Vulpes vulpes), badger (Meles meles) and beech marten (Martes foina) are all in apparent increase. The weasel (Mustela nivalis), although to a lesser extent, appears to be well-distributed over the whole area; the western polecat (Mustela putorius) has become very rare and is endangered. The presence of the otter (Lutra lutra) in the past should also be mentioned. The fragmented and degraded landscape of the Veneto-Friuli plain does not meet the ecological requirements of this species (rivers full of fish, with banks thickly covered in woodland), so the possibility of reintroducing it at local level is not promising. Lastly, bats mainly frequent lagoon areas as places to feed and rest. Knowledge of local chiropterans is still very scarce, as bats are one of the most difficult groups of vertebrates to study. As well as species which roost in buildings, such as the serotine (Eptesicus serotinus), Kuhl’s pipistrelle (Pipistrellus kuhlii) and Savi’s pipistrelle (Hypsugo savii), there are others which clearly require woodland. These include the noctule (Nyctalus notula), Nathusius’s pipistrelle (Pipistrellus nathusii), and Daubenton’s bat (Myotis daubentonii), which prefers habitats with plenty of channels and open bodies of water. 133
Page 1 and 2: Terrestrial invertebrates MARCO ULI
Page 3 and 4: 96 ■ Molluscs The malacological f
Page 5 and 6: 100 ■ Heteropterans The typical h
Page 7 and 8: 104 the wet mud on the coastline, a
Page 9 and 10: 108 ■ Dipterans The dipterans of
Page 11 and 12: Terrestrial vertebrates MAURO BON
Page 13 and 14: 116 117 Great crested grebe (Podice
Page 15 and 16: diver (Gavia arctica) and red-throa
Page 17 and 18: 124 Recent artificial environments:
Page 19: 128 aquatic birds, especially dabbl
Page 23 and 24: agriculture and livestock farms sur
Page 25 and 26: 140 These environments are protecte
Page 27 and 28: Teaching suggestions MARGHERITA SOL
Page 29 and 30: 148 How to identify molluscs More t
Page 31 and 32: 152 RELINI G., BERTRAND J., ZAMBONI
Page 33 and 34: 156 Gibbula - 49, 52 Heterocerus -
Page 35: The authors wish to thank the follo

Terrestrial invertebrates - Udine Cultura

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