Volume 36 - N. 2
December 2012

Avocetta
Volume 36 - N. 2



  1. Tuna farms – a seasonal supplementary food source for storm petrels Hydrobates pelagicus melitensis

    Borg J.

    Abstract     Read Article       Download
    9 37

    The area investigated is located about 9 km east from the nearest shoreline at Marsascala (Malta), ca. 30 km from the main
    breeding colony of Filfla, situated 5 km off the south coast of Malta. The use of raw, unwashed fish food is fundamental in attracting storm
    petrels closer to these tuna pens. The same food supply has attracted a constant presence of small fish around the pens which in-turn at

    tract gulls and terns, especially the black tern. Observations have shown that the majority of storm petrels frequenting the area are adult
    birds undergoing primary wing moult, suggesting breeders, probably not venturing far away from the colonies during the chick rearing
    period. While adult storm petrels regularly fall prey to yellow-legged gulls on Filfla, no interactions between gulls and storm petrels were
    ever noted near the tuna pens.

  2. Night surveys and smell, a mixed method to detect colonies of storm petrel Hydrobates pelagicus

    Albores-Barajas Y.V., Massa B. , Lo Cascio P. , Soldatini C.

    Abstract     Read Article       Download
    12 30

    Storm-petrels usually breed in sites difficult to access, making it hard to estimate the number of individuals in a colony or even the presence of a colony. After several years of study in the main colony and diurnal surveys to other caves of the island, we planned an extensive night survey for identifying previously unknown colonies. In the breeding season of 2011 we found 5 new colonies of storm petrels ( Hydrobates pelagicus) at Marettimo island, increasing the estimation of the population on this island to approximately 3000 breeding pairs. We propose the use of mixed methods to locate new colonies, as they can be found by the characteristic smell of storm petrels, but under windy conditions it would be difficult. It is therefore very important to use night surveys to observe night activity by the individuals.

  3. Breeding birds in agro-forest habitat types (Nazzano, Tevere-Farfa Nature Reserve, central Italy): evidencing patterns following a dominance/diversity approach

    Angelici C.,2 , Brunelli M., Battisti C.

    Abstract     Read Article       Download
    9 43

    We analysed bird assemblages breeding in three coarse-grained habitat types (cultivated lands, forests and mosaics) by fol-
    lowing a dominance-diversity approach. Although we did not observe significant differences in mean values of both species richness
    and abundance among habitat types, assemblages of cultivated lands showed the lowest values of all diversity metrics. Low values of
    β-turnover index highlighted low heterogeneity of these anthropic and simple habitat types. The dominance/diversity diagram showed a
    clear difference between slopes of rank-frequency lines of mosaics and forest habitat types when they were compared to cultivated lands,
    indicating low species evenness resulting from the high disturbance, typical of agro-ecosystem assemblages. At this scale when we com-
    pared mosaics to forest habitats, rank-frequency lines appeared over imposed, suggesting that breeding bird assemblages did not perceive
    differences between these habitat types
    .

  4. Spring arched migration of black kite Milvus migrans over the Apuane Alps (Tuscany)

    Premuda G., Baghino L.

    Abstract     Read Article       Download
    11 29

    The aim of this study is to analyse the migration flow of black kite
    Milvus migrans
    observed in Northwestern Italy. Observations were carried out on the western slopes of the Apuane Alps (Capriglia, Pietrasanta, Lucca, Tuscany), over the period 4 March – 1 April 2002-2011, where 189 black kites were recorded. Most black kites observed (N = 176, 93%) had a reversed direction of spring migration, from NW to SE. The regularly observed behaviour of black kites in the Apuane Alps and the positive correlation between the migration trends at the Apuane and Arenzano (Genoa) study sites show an arched migration strategy, performed probably by a small portion of the Central Italian population, which follows the coastline to avoid crossing the Mediterranean sea, and also suggests the occurrence of a spring circuitous migration, as has been documented in the short-toed eagle.

  5. Nuove analisi sulla migrazione post-riproduttiva del biancone Circaetus gallicus nell’Italia nord-occidentale.

    Baghino L. , Premuda G. , Giraudo L.

    Abstract     Read Article       Download
    10 52

    New analysis on post-breeding migration of short-toed eagle Circaetus gallicus in north-western Italy.
    The autumn migration of the short-toed eagle Circaetus gallicus was studied from 15th to 26th September, in 2005, 2006 and 2007, at three sites in NW Italy: Stura Valley (S Piedmont), Arenzano (W Liguria) and Apuane Alps (NW Tuscany). During this 3-year period, 746, 2085 and 2352 short-toed eagles were respectively counted at these three sites: correlations in both time and migration volume were found between the Apuane Alps and Arenzano, but not with the Stura Valley, where the migrating populations are probably of different origins (N Italy, with some reports of birds moving SW already from sites in the NE regions of Italy). Interestingly, the significant counts at the Apuane Alps suggest that birds performing this circuitous migration may involve a rather wide area through Central and Southern Italy; moreover, occasional findings on the Adriatic side of Central Italy (birds heading NW) would seem to show that this circuitous migration may also have a degree of longitudinal extension. During the second half of September a fair proportion (<20% of the whole volume) of juveniles is regularly observed at both Apuane Alps and Arenzano sites, and their migration dates are very close to the main adult movement, in agreement with the strategy to follow the adults performed by a portion of the juveniles.

  6. Year-round use of the Regional Nature Reserve of Nazzano, Tevere-Farfa (Latium, central Italy) by waterbirds

    Angelici C., Brunelli M.

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    10 35

    From 2007-2011, surveys were carried out to describe the presence of waterbirds in the Regional Nature Reserve of Nazzano, Tevere-Farfa. The key parameters of the community were analysed: richness, abundance, dominance, diversity, evenness and daily energy expenditure for each 15-day period in which counts were made. A census for all breeding species was also carried out. Forty-nine species were encountered, the most abundant of which was Anas platyrhynchos,Fulica atra and Gallinula chloropus. There was nega­tive trend in the bird population for all species combined during the years of the study, probably caused by the worsening of the water conditions due to a decrease of aquatic macrophytes. Management actions proposed aimed at improving food availability and creating wetlands with different water levels.

  7. Andamenti di popolazione delle specie comuni nidificanti in Italia: 2000-2011

    Campedelli T., Buvoli L. , Bonazzi P. , Calabrese L. , Calvi G. , Celada C. , Cutini S. , De Carli E , Fornasari L. , F ulco E. , La Gioia G. , Londi G. , Rossi P. , Silva L. , Tellini Florenzano G.

    Abstract     Read Article       Download
    17 50

    Population trends of common species nesting in Italy: 2000-2011 . Since 2000, the Mito2000 project aims to monitor populations of common Italian breeding species. Every year, chosen by means of a randomized design, a variable number of 10×10 km grid squares are surveyed, doing, for each of these, 15 point counts of 10 minutes length. On his twelfth year, 643 are the squares surveyed at least two times and therefore useful to estimate population trends (using the software Trim). At the beginning of the project, 103 target species were identified and now, for 87 of these, defined population trends are now available; in addition, defined trends are also available for other 30 non-target species. Grouping the target species according to their ecology, the results point out a clear decrease in farmland birds (FBI index), and even a greater decrease for the species of mountain grasslands (PM index); by contrast, woodland species index increases sharply (WBI index). These results agree well with the results of sibling projects in other European countries, confirming the known trends in the evolution of environmental systems, stressing the reliability of Mito2000 project for monitoring trends in a group of important biodiversity indicators, the breeding birds.

  8. Prime nidificazioni con successo del Gipeto Gypaetus barbatus  sulle Alpi occidentali italiane

    Fasce P., Fasce L.

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    11 86

    First successful reproductions of Bearded vulture Gypaetus barbatus in the Italian Western Alps. Authors report the first successful reproductions of Bearded vulture in the Italian Western Alps, from a trio in Val di Rhêmes and a pair in Valsavarenche (Aosta Valley). They summarize the history and behaviour of the polygynic trio, from its formation in 2008 through two failed reproductions in 2010 and 2011, till the successful flight of a chick in 2012. Additionally, they summarize the reproduction in 2011 of the pair of Valsavarenche, failed very likely in consequence of the precocious age of both partners, and the successful one in 2012.

  9. Book Reviews – Recensioni

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    18 46