1,721,062 research outputs found
A comparison of two methods for monitoring migrating broad-winged Raptors approaching a long water crossing
Full text linkObservations on raptor migration were carried out at the island of Marettimo (Central Mediterranean) during the first half of October 2007. Raptors concentrate at this site before crossing the Channel of Sicily en route to Africa (130 km). We used and compared two different census methods in order to limit the problem of double-counting of migrating raptors. A total of 510 and 299 individuals were respectively counted using two different methods: the first one is the standard method in use to count migrating raptors (all-occurrence), the second one consists in considering the maximum number of raptors observed together for each observation day (maximumdaily-count). Raptors observed were almost juveniles and immatures (inexperienced individuals). For short-toed snake eagle Circaetus gallicus, booted eagle Aquila pennata and common buzzard Buteo buteo, the results show signifcant differences in counts. Weather conditions affected observed numbers of these species at the site, although they did so similarly for both methods. Results show that, at Marettimo, it is not possible to make an accurate count of inexperienced broad-winged raptors approaching the long water crossing. For this reason we suggest to consider as an activity index the daily count of the maximum number of birds of the same species observed together during each day of field work
Local and regional wind patterns affect spring migration magnitude, flyways and flocking of European Honey-buzzards Pernis apivorus at the Strait of Messina
No full textSummary . During spring migration, a few tens of thousands of European Honey-buzzards wintering in sub-Saharan Africa cross the central Mediterranean to reach their breeding grounds in central-eastern Europe. In so doing they concentrate passage through the Sicilian Channel but choose different flyways in response to different wind conditions. This study investigated the influence of local and regional wind conditions on the movement patterns of this species along the Strait of Messina, a migration bottleneck located between eastern Sicily and southern continental Italy where some raptors fall victim to illegal shooting by poachers each spring. Simultaneous observations occurred at four watchpoints, three on the Sicilian side and one on the continental boundary (Calabrian side). Although northwesterly winds prevailed at the Strait during peak migration days, slightly different local patterns of both horizontal and vertical winds at each observation site affected flocking and shaped the passage of raptors through this bottleneck, broadening the migration front. The results confirm that the magnitude of Honey-buzzard spring migration at the Strait is strongly affected by wind patterns in the Sicilian Channel. In particular, migrants concentrate at this bottleneck after crossing the Channel in northwesterly winds the previous day. In conclusion, by interpreting migratory behaviour both at local and regional scales, this work can help to plan more efficient monitoring of Honey-buzzards through the Strait and improving the siting of conservationist efforts. - Agostini, N., Chiatante, G., Gustin, M., Cento, M., von Hardenberg, J., Dell'Omo, G. & Panuccio, M. (2021). Local and regional wind patterns affect spring migration magnitude, flyways and flocking of European Honey-buzzards Pernis apivorus at the Strait of Messina. Ardeola, 68: 373-390
Sistematica del Falco pellegrino (Falco peregrinus) in Italia
No full textValidated data and published studies indicate that four subspecies are present in continental
Italy and its surrounding islands. Two of these subspecies (F. p. peregrinus and F. p. brookei) represent
breeding populations, while the other two (F. p. calidus and F. p. pelegrinoides) winter and migrate
in the country. Indeed, the European subspecies (F. p. peregrinus) has the most intriguing status, as it
can both breed and winter. The exact range of the breeding population is not well-defined - it probably
occurs in alpine and pre-alpine areas, perhaps reaching the Apennines of central Italy. Individuals
originating from northern European countries in autumn and winter certainly implement this breeding
population, as shown by ringing recoveries. In southern Italy the range of the breeding European peregrine
is complementary or intergrades with that of the Mediterranean subspecies (F. p. brookei), which
is present also in Sicily and Sardinia. A genetic investigation of a sample of Italian individuals showed
new distinct Sicilian haplotypes, nonetheless the overall allelic patterns and genetic structuring of microsatellites
were similar to those of other European populations. Regarding the other two subspecies:
the Barbary Falcon’s (F. p. pelegrinoides) presence in Italy is purely accidental. The Siberian Tundra
Peregrine (F. p. calidus), instead, is a regular wintering visitor in several regions of the country; several
observations occur every year, and these have been increasing recently, due to a growing number of
amateur and professional birdwatchers
Mercury, Lead and Copper in Feathers and Excreta of Small Passerine Species in Relation to Foraging Guilds and Age of Feathers
No full textIn the present study excreta and feathers of five species of adult passerine birds from Montepulciano wetland (Siena, Italy) were assayed for trace elements between January and August 2006. Lead concentrations varied from 16.31 to 26.50 mg/kg and were found strictly related to the age of feathers. Copper levels were found to be high mainly in insectivorous birds (9.68 mg/kg) and were probably influenced by local use of copper-based agricultural fungicides. Mercury accumulation in feathers varied between species from 0.08 to 0.73 mg/kg. The role of feeding habits on trace elements levels in feathers and excreta is discussed. © 2009 Springer Science+Business Media, LLC
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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