Volume 40 - N. 1
June 2016

Avocetta
Volume 40 - N. 1



  1. Bird Homogenization at regional scale (Umbria, central Italy): a lack of evidence for a change in the 2001-2014 period

    Velatta F., Lombardi G., Sergiacomi U.

    Abstract     Read Article       Download

    The decline of stenoecious species and the development of euryoecious species are causing a flattening of communities, which gradually lose their peculiar characteristics ending up being more and more similar among themselves and causing a general loss of biodiversity. Amongst the various causes of this phenomenon, known as ‘functional homogenization’ (FH), lies the urbanization which is responsible for the alteration of semi natural and natural environment. The environmental transformation is also affecting Umbria (a region in the centre of Italy) where in recent years there has been a significant intensification of this phenomenon. The purpose of the study is to verify whether FH is also happening in this region by analyzing the community of breeding birds to a regional level. Starting from a sample of 1,696 bird watching stations covered between 2001 and 2014, using the software TRIM it was possible to analyze the trend of 132 bird species classified as specialists and generalists in terms of habitat-selection. Furthermore, for each year taken into account it has been calculated the value of Community Specialization Index (CSI – Filippi-Codaccioni et al., 2010), an indicator of the importance of specialist species within the whole regional bird community. Finally, it was considered the degree of difference amongst the bird communities from different parts of the region (subdivided into 102 UTM squares each covering an area of 100 km2) using the average Euclidean distance (AED) between the various squares which was calculated based on the levels of abundance of the different species. The presence of FH would have implied the following: a tendency of increase of generalist species, a decrease of the specialists, a CSI reduction, a AED reduction. During the period considered it was observed that there was an increase of over half (50.7%) of generalist species, whereas just 23.2% was declining. Amongst the specialists, the declining species were equal to those increased (12.7%). Although there was an increment of the generalist species, the indexes CSI and AED did not show any significant trend (Spearman test). Overall, our findings do not describe the occurrence of a homogenization process in the last decade of the regional bird community as a whole.

  2. Seasonal variation in wing length and body mass in the Northern Wheatear Oenanthe oenanthe at the Gran Sasso area

    Strinella E., Pirrello S., Artese C., De Faveri A.

    Abstract     Read Article       Download

    In this study, we use the ringing data on Northern Wheatears captured during the period 2004-2013 in the Gran Sasso area. We considered 3222 ringed individuals to analyze seasonal variation in wing length and body mass of adults (males and females) and juveniles. During the breeding season (7 May-4 August) the wing length of adults was 2.8 mm longer in males, whereas the body mass did not differ between the sexes. The wing length increase in August can be caused by the passage of adults and juveniles from other territories that likely replaced individuals that were present during the breeding season in this area. In addition, the inter-annual fluctuations of captures probably reflected variations in weather condition between years, which is one of the major factors influencing the timing of migration (e.g. bad weather solicits early departures from breeding grounds) and reproduction (e.g. bad weather delays depositions and increases the parental effort) of high altitude bird species.

  3. Comparison between two molecular protocols for sex determination in birds, with implications for the management and conservation of the Eurasian Griffon vulture Gyps fulvus

    Garofalo L., Fanelli R., Opramolla G., Polidori M., Tancredi F., Altea T., Posillico M., Lorenzini R.

    Abstract     Read Article       Download

    Sex ratio is a parameter worth to be monitored in small animal populations, as it has wide implications for their conservation. Morphological sex identification in birds, especially in the Accipitridae, can be difficult if the animals are young or when there is no appreciable sexual dimorphism. Sex determination can be impossible when few and/or degraded biological material (e.g. feathers, blood traces, decomposed carcasses) is available. In this case, molecular markers represent the analytical method of choice. Two molecular Amplification Refractory Mutation System (ARMS) protocols, both based on the amplification of portions of the Chromo-Helicase DNA-binding protein (CHD1) gene, were tested on tissues from 6 Griffon vultures Gyps fulvus of known sex, and subsequently, on 9 shed feathers (i.e. degraded samples from individuals of unknown sex) collected on feeding sites. Protocol 1 consisted of one PCR reaction yielding two amplicons with larger sizes than those produced with Protocol 2, which, in contrast, consisted of two PCRs. Our results show that, overall, both molecular protocols are suitable for sex identification in the Griffon vulture. In particular, when good quality/quantity DNA is available (e.g. DNA from feathers of live animals, fresh or frozen blood and tissues), Protocol 1 was faster than Protocol 2, since one single PCR is performed. On the other hand, Protocol 2 can better suite to poor or degraded DNA (e.g. extracted from shed feathers or decomposed tissues), because the two amplifications produce smaller fragments. We selected Protocol 1 to analyse good quality DNA from feathers of 89 free-ranging Griffons, sampled during capture and ringing activities (years 2013-2015) by the Forest Service within the Monte Velino Reserve (central Apennines, Italy). The sex ratio obtained for this reintroduced population was 1: 2.07 (29 females and 60 males). We also explored the potential of applying this method in other 10 bird species: molecular and morphological identification of sex always yielded concordant results. This study shows that Protocol 1 can be used for sex identification in Griffons and other mainly monomorphic species for which population studies or monitoring programs are planned, or when sex could not be determined from few remains of otherwise dimorphic species.

  4. An exploration of isotopic variability in feathers and claws of Lesser Kestrel Falco naumanni chicks from southern Sicily

    Morganti M., Franzoi A., Bontempo L., Sarà M.

    Abstract     Read Article       Download

    Stable isotopes are nowadays commonly used in the study of many key features of avian ecology. However, the adequate choice of what isotopic ratio to consider and what tissues to sample for assessing specific questions may be tricky. Here, we explored the variation in a suite of stable isotope ratios (δ13C, δ15N, δ34S, δ2H, δ18O) in the feathers and claws of chicks of Lesser Kestrels Falco naumanni from south-eastern Sicily (Italy) sampled throughout colonies of the same population but surrounded by different habitats. Our aims are to provide an insight into the isotopic ecology of Lesser Kestrel and to provide methodological indications for future studies. Specifically, we tested whether stable isotope ratios (i) were consistent between feathers and claws; (ii) differed within and between colonies; (iii) reflected differences in surrounding habitats. We found that all isotope ratios significantly differed between claws and feathers. Hierarchical cluster analyses revealed a high consistency of stable isotope ratios for all the elements between siblings and nests within the same colony. Significant differences in stable isotope ratios emerged among colonies and were associated to differences in the surrounding habitat. The isotope approach has great potential in the study of lesser kestrel ecology, and our results suggest which element should be selected to approach a set of different ecological questions.

  5. Factors affecting the diet of Peregrine Falcon in Italy

    Bondì S., Guzzo E., Vitale E., Baragona A., Grancagnolo D., Sarà M.

    Abstract     Read Article       Download

    The diet of top predators can provide useful information on phenology and abundance of their prey. The cosmopolitan and specialist Peregrine Falcon Falco peregrinus is an ideal model to assess whether food changes have occurred in the long-term. In this contribution, we reviewed all available literature on Peregrine Falcon diet in Italy which contained 11 detailed datasets useful for our review, and also included analysis of pellets, collected at three breeding sites of Sicily during 2014 and 2015. These data allowed us to shed light on the Peregrine Falcon’s diet over the last forty years (1978-2015). We calculated the numerical and biomass percentage of the resident and not-resident prey proportions, as well as the trophic diversity of diet in each site using the Simpson diversity index. To describe the Peregrine Falcon food niche and investigate whether year, habitat and latitude effects existed in its diet, we used a 2nd-degree factorial ANOVA. Over 1,550 prey, 110 bird species accounted for 98.58% of frequency and 99.79% of biomass. Modelling showed a year effect, with the quota and biomass of resident prey species increasing across the forty years of the study period, in a way complementary to the decrease of the quota and biomass of not-resident prey species. Conversely, habitat and latitude predicted significantly trophic diversity that was larger in rural than urban habitats, and at northern than southern latitudes. The strong numerical and biomass decrease of not-resident prey in the trophic niche of Peregrine Falcon in Italy could be related to the negative population trends of both migratory and summer-breeder farmland species. Actually the bulk of prey of the Peregrine Falcon in Italy is formed by a restricted group of resident Corvidae and Columbidae, which have remarkably increased in the last years. This could trigger more dependence on resident prey in the long term, making the Peregrine Falcons more vulnerable to control programs or eradication of specific prey populations or exposing them locally to high risk of infections (chlamydiosis, avian trichomiasis) transferred by feral species.

  6. An unusual nest location in House Martin Delichon urbicum: A case of compensation behaviour?

    Ferri V., Battisti C., Brunelli M., Soccini C.

    Abstract     Read Article       Download

    Short Communication

  7. Columns - Book Reviews

    Abstract     Read Article       Download

    Book Reviews