Carlo Guzzon’s research while affiliated with University of Pavia and other places

During 2017 a comprehensive census of heron and cormorant colonies was carried out in the whole Veneto, Trentino-Alto Adige and Friuli Venezia Giulia regions (NE Italy). 162 colonies were monitored, with 7460 – 7979 pairs found. In Trentino Alto Adige there were 18 colonies, in the Veneto 127 and 17 in Friuli Venezia Giulia. Nine species were confirmed to have bred: Grey Heron (2516-2720 pairs), Cattle Egret (678-709), Little Egret (953-1036), Night Heron (342-376), Purple Heron (450-464), Great White Egret (2), Squacco Heron (34-38), Cormorant (989-1011) and Pygmy Cormorant (1496-1623), while breeding of Sacred Ibis is considered only possible. For the Veneto only, data is available from 1987-2017: the total number of breeding birds in heron colonies, after a sharp increase between 1987 and 2000, thereafter remained relatively stable at around 4000 pairs. From 2000 at 2017 the trend of individual species is contrasting: Grey Heron and Cattle Egret numbers have grown rapidly or very rapidly, while Little Egret and Purple Heron are in marked decline. For Night and Squacco Herons the estimates are less certain. Cormorant and Pygmy Cormorant numbers, between 2000 and 2017, have risen sharply.

[In 2008-2014 wader and seabird nesting pairs were censused along the 220-km long coastline of the NE Adriatic Sea, in the Veneto and Friuli-Venezia Giulia regions (NE Italy). Fourteen species were regularly breeding, with an annual mean of 20,610 pairs (±1553, 1 SD). The most abundant species was the Yellow-legged Gull (about 13,400 pairs on average, 65% of the whole population of the study area), followed by the Common Tern (1670 pairs, 8.1%) and Common Redshank (1525 pairs, 7.4%). The whole population of waders and seabirds increased with an annual rate, estimated with the TRIM software, of +0.8%, with a greater increase (+4.3%) if the Yellow-legged Gull was not included. Twelve species were stable or increasing; only the yellow-legged gull (-1%) and the common redshank (-2.4%) were decreasing. The populations of several species exceed 10% of those estimated for the whole of Italy; those of the Eurasian Oystercatcher, Common Redshank and Sandwich Tern are among the most important in the whole Mediterranean. On average, about 8860 pairs (43%) nest in the Venice lagoon, 6,400 pairs (31%) in the Po Delta, 5100 pairs (25%) in the Friuli-Venezia Giulia lagoons. Among nesting habitats, semi-natural (such as the fish farms) and man-made sites (dredge islands) make each year about 70% of the nesting pairs. Saltmarsh islets host large numbers of Common Redshank and Sandwich Tern, while along the beach zone the only abundant species are the Yellow-legged Gull and the Eurasian Oystercatcher. The major conservation threats observed in the study area were the erosion of littoral islands, the uncontrolled occurrence of sunbathers along the beaches, the vegetation overgrowth at dredge islands, the increasing frequency of saltmarsh submersion by high tides, the strong fluctuations of water levels inside the fish farms.] [Article in Italian]

Wetlands belong to the most highly threatened habitat types on our planet. In Europe, many wetlands have been destroyed or degraded by human activities, including drainage, agricultural land use, industrialization, regulation and damming of river courses, pollution, eutrophication, invasions of non-native species and other actions. In northern Italy, many wetlands have disappeared and been replaced by intensive croplands or industrial areas, leading to a drastic decline of many wetland species. The Adriatic Marbled Bush-Cricket, Zeuneriana marmorata (Fieber, 1853), is a rare bush- cricket species, which is found in a few wetlands in north-eastern Italy (Friuli Venezia Giulia) and Slovenia. It has a loud and highly characteristic song, which creates a unique acoustic atmosphere in the very few places where it still exists. The species occurs in coastal reed beds (Fig. 1), where it is only found where the reed vegetation is not too dense and the water not too saline. Only four populations of this species still exist with an estimated total of 3,000- 5,000 adult individuals per year (a very small number for an insect species). The entire remaining habitat of this species has a size of 0.57 km² (57 ha) with only ca. 16 ha being left in Italy. Z. marmorata is quite sedentary and sensitive to habitat destruction.

In this paper are reported three new localities of Zeuneriana marmorata (Fieber, 1853), located in two different coast areas in Friuli Venezia Giulia Region. On June 2014 the species was found at the Isonzo mouth, near the village of Fossalon di Grado. On July 2016 Zeuneriana marmorata was discovered in two localities of Marano Lagoon, in the Stella delta and in an area located between Cormor and Muzzanella river. At the present time the known populations of this rare species live in four areas, three in Italy (Marano Lagoon, Isonzo mouth, Lisert near Monfalcone) and one in Slovenia (Ljubljansko Barje near Lubjana). In Italy Zeuneriana marmorata lives in wet meadows and reed-lands, which are periodically flooded and whose vegetation is prevalently constituted by Phragmites australis, Juncus sp. and Carex sp.; in Italian sites located along the Adriatic coast, the species can tolerate a low salinity. The species do not live in sites, which are flooded for long periods during the good season. Zeuneriana marmorata is an endangered species, due to its rarity, its restricted ecological requirements and the vulnerability of its habitat. One of the Italian sites (Lisert) needs urgently interventions to restoring and conserving the wet habitats suitable for this species.

During 2002, we accomplished a new national census of the heronries of Italy, that had previously been undertaken in 1981 and 1986. For the whole country, the number of heronries increased, from 71 colonies in 1981 to 290 colonies in 2002. The grey heron Ardea cinerea expanded its breeding range eastwards and southwards, and increased the number of its nests (13075 nests in 2002) by 20 times compared to its number in 1981; the purple heron Ardea purpurea (2269 nests) increased 2.5 times; the little egret Egretta garzetta (15729 nests) increased by 2.4 times; the night heron Nycticorax nycticorax (13293 nests) is the only species that decreased, albeit not dramatically (by 23% in 2002 compared to 1981). The great white heron Casmerodius albus (38 nests) and the cattle egret Bubulcus ibis (1192 nests) are new breeding species. In north-western Italy, the heronries were 106 in 2003, a remarkable increase from the 46 heronries recorded in 1981. The breeding populations increased greatly during the past two decades for grey herons, little egrets, purple and squacco herons. Cattle egrets began breeding in 1989, and great egrets in 1998. Only night herons decreased in terms of number of nests, albeit increasing in number of colonies occupied. In north-eastern Italy we found 96 colonies, most of which were inside wetlands such as rivers, marshes, lagoons, restored wetlands, abandoned clay and gravel pits. Compared to the 1981 survey, a great increase took place both in the number of heronries (from 16 to 96) and in the number of nests (from 5914 to 10806 for all the seven species). Purple and squacco herons showed the largest increase. Grey and great white herons, and cattle egrets started breeding in the area. Little egrets remained stable, whereas night herons decreased. In central Italy, we found 26 heronries and 3 cases of isolated nests, totalling 2930 nests, again a considerable increase compared to the 1981 census.The heronries, once restricted to the Tyrrhenian sector, are now widely distributed throughout all central Italy. Four heronries were recorded in continental southern Italy. In Sicily, five species of herons and egrets bred regularly at two sites, and sporadically at some artificial ponds. In Sardinia, we recorded 56 heronries, mostly scattered along the coast, or clumped within the main wetlands. The total number of nests in Sardinia increased from 407 in 1986 to 1554-1682 in 2002. Overall, the increase in range and population size observed for 6 species of colonial herons and egrets out of 7 is likely due to multiple factors, including warmer winter temperatures and diminished human persecution, but it is also related to specific actions for their conservation, that included specific reserves for the protection of heronry sites.

Nei periodi ottobre-gennaio 2005/2006 e 2006/2007 sono stati effettuati censi-menti mensili degli Uccelli acquatici svernanti all'interno delle valli da pesca arginate della Laguna Sud di Venezia, estese per un totale di circa 3700 ettari. I risultati hanno evidenziato presenze complessive mensili comprese tra 80381 (ottobre 2005) e 113696 individui (novembre 2006), con una media di 99622 individui. Gli andamenti sono risultati diversi nei due inverni, con una sostanziale stabilità tra novembre e gennaio nel 2005-06 ed una diminuzione nel secondo inverno. Gli Anatidi sono risultati il gruppo più numeroso, con una media mensile di circa 73000 individui. Le due specie più abbondanti sono risultate l'Alzavola (Anas crecca, media di circa 36000 individui) ed il Germano reale (Anas platyrhyn-chos, media di 25724 indd.). La distribuzione degli animali è estremamente disomogenea, con densità minime di 4.6 indd./ha e massimo di 68 indd./ha; si ritiene che ciò sia da attri-buire alle caratteristiche ambientali ed alla diversa gestione antropica di ogni singola valle da pesca. Abstract. Fall-winter censuses of waterfowls in the fish farms of the Southern Lagoon of Venice (Italy): years 2005-2007. Monthly censuses of wintering waterbirds were performed between October and January, in the years 2005-2006 and 2006-2007, within the fish farms of the southern Lagoon of Venice (Italy). These consist of 3700 ha of mostly embanked, brackish water basins. Monthly occur-rences ranged between 80381 (October 2005) and 113696 birds (November 2006), with a mean of 99622. Trends turned out different between the two winters: numbers were stable between October 2005 and January 2006, whereas a decrease was observed in the second season. Ducks were the most abundant group, with a mean occurrence of 73000 birds. Teals (36000 birds) and Mallards (25724 birds) were the most abundant species. Spatial distribu-tion of wintering birds was highly uneven, with densities ranging between 4.6 birds/ha and 68 birds/ha; this was likely due to both environmental aspects and different fish farm mana-gement by owners.