Volume 24 - N. 2
The influence of nest site
characteristics on frequency of use and breeding success in the Cory’s
Shearwater Calonectris diomedea
Mougin J. L., Mougin M.C.Abstract Read Article Download21 63
In the Cory’s Shearwater Calonectris diomedea borealis of Selvagem Grande (30°09’N, 15°52’W), information was collected for 15 consecutive years on frequency of use and breeding success at 529 nest sites, the physical characteristics of which were measured or coded as ranked variables. Nest type and presence of material outside the nest site were found to have significant effects on both parameters but there were no effects of location, density, vegetation cover or type of floor. Cory’s Shearwaters being faithful to their mate and nest site, the frequency of use of a nest site is likely to be more dependant on the length of pairings and on the hazards of repairings than on nest qualities. Breeding success is also likely to depend on the qualities of the breeders more than on those of the sites.
Selezione di habitat e riproduzione dell’Averla capirossa, Lanius senator, nel Lazio – Italia centrale
Guerrieri G., Castaldi A.Abstract Read Article Download17 49
The reproductive biology of Woodchat Shrike, Lanius senator, has been studied for seven years (1992-1998) in a sample area of Central Italy. The settlement of the species in Latium, is influenced by May rainfall. The pairs number, greatly variable (+/- 50 %), varies between 1.40 and 2.04 pairs/km2 (max. 5 pairs/km2). Woodchat Shrike, sympatric with two other species of the same genus which nest in Italy (L. collurio, L. minor), seems to prefer xerophytic pastures with scattered shrubs (20 %). The interspecific competition is less intense than the intraspecific one. Nests are preferably located on shrubs which have a mean height of 3.39 m (S.D. = 1.31) and the mean height of nest site is 1.97 m (S.D. = 0.64). During laying of replacement clutches, when pairs are consolidated, singing activity is significantly reduced. If the first hutching is unsuccessful, Woodchat Shrike avoids to place the second nest where predators are facilitated. Average clutch size (4.61; S.D. = 1.01) is one of the lowest in the reproductive areas. The 4.41 of the eggs is sterile. The 41.5 % of the pairs fails the first reproduction and the 13.6 % is not able to reproduce at all. The average number of juv. / pairs successful in hutching is 3.1 juv./pairs (S.D. = 1.16; juv./eggs = 0.575). In this region, adults seem to move away from the reproductive area sooner than juvenes.
The islands of Marettimo (Italy), important bird area for the autumn migration of raptors
Agostini N., Logozzo D., Panuccio M.Abstract Read Article Download26 55
A survey on the autumn migration of raptors over the island of Marettimo (western Sicily) was carried out from 27 August to 9 September 1997, and from 26 August to 14 September 1998. A total of 3177 and 5227 birds was counted, respectively. Each year, nearly all raptors observed were Black Kites Milvus migrans and Honey Buzzards Pernis apivorus. These species showed a strong tendency to migrate in large flocks. During 1998 it was possible to age some migrating birds; a notable overlap in the migration periods of adult and juvenile Black Kites occurred, while nearly all Honey Buzzards aged were adults. This study confirms the hypothesis that adult Honey Buzzards cross the central Mediterranean at its narrowest point, using the same route as in spring and showing true navigational abilities. Finally, on the island of Marettimo, occurs the greatest concentration of Black Kites and Egyptian Vultures Neophron percnopterus during post-reproductive movements on the central Mediterranean. These results suggest that this site should be included among the Important Bird Areas for the autumn migration of raptors.
The Autumnal Diet of Rock Partridge (Alectoris graeca) in the Central Apennines
De Sanctis A., Pellegrini M. ,Biondi M. , Manzi A., Massa B.Abstract Read Article Download27 58
A preliminary study on the autumnal diet of the Rock Partridge (Alectoris graeca) in the Central Apennines was carried out through the analysis of 21 gizzard contents. Considering both the number of species present and the variety of parts of plants consumed the diet was rather diversified. Green parts of plants were always found, especially Cistaceae (Helianthemum oelandicum) and Leguminosae. Seeds and fruits were present in 85.5% of the gizzards and the botanical families represented most frequently were Compositae, Fagaceae (Ostrya carpinifolia and Fagus sylvatica), Cistaceae and Leguminosae. Roots and bulbs appeared less frequently (14%). Coleoptera Chrysomelidae and Orthoptera were found respectively in 43% and 33.3% of the gizzards and constituted 94.5% of the total number of arthropods. Most of these taxa are linked to rocky slopes, xerophilous and short grass pastures, or abandoned fields. These results stressed the importance of maintaining and managing a mosaic of habitats for the conservation of this bird.
Song clinal variability in Passer italiae, a species of probable hybrid origins
Fulgione D., Esposito A.,Rusch C. E., Milone M.Abstract Read Article Download23 69
Songs are commonly used to measure the clinal variation in hybrid zones. The Italian sparrow populations are currently considered as stabilised hybrids. Their range is delimited by two contact zones: Alpine area and Sicily island with two parental species, Passer domesticus (North European species) and Passer hispaniolensis (North African and south Mediterranean islands specie) respectively. The Italian sparrows (Passer italiae) show intermediate traits according to genotypic and phenotypic clinal variation through the Italian peninsula. In an analysis of song display in Italian sparrow we have used the male territorial marker song as distinctive display between populations. We have recorded and compared the song of male Italian sparrows with those of the two parental species using spectrogram analysis. By multivariate analysis we have found a clinal variation from P. hispaniolensis to peninsular Italian sparrow. This pattern is broken in the Alps where Italian sparrow populations and P. domesticus show similar song structure among each other.
Finding out who is nesting where: a method for locating nest sites of hole-nesting species prior to egg laying
Grieco F.Abstract Read Article Download21 49
A method to find out which species is more likely to start egg laying in a certain nestbox is described. Nestboxes were visited daily and the behaviour of the birds (Great, Blue and Coal Tits) that appeared around the nestbox was observed. The birds’ response consisted mainly of giving alarm calls and showing inquisitive behaviour (i.e., approaching the observer and looking at close distance). Proximity of the individual (or the pair) to the nest and inquisitive behaviour of the female bird were found to be associated with nest ownership. Alarm calling and inquisitive behaviour of males were less selective and therefore not diagnostic. Nocturnal check of nestboxes provided useful information about the nest owners, but they were more reliable at late nest-building phases, when the female was closer to egg laying. It is suggested that this observation method may be used in field studies of species breeding in nestboxes or even natural cavities. This work emphasises the importance of observing small details of behaviour as symptoms of the condition ‘inside’ the individual (motivation).
Differences in reproductive performance between two colonies of egrets in two areas with different human influence
Parejo D., Sanchez J. M., Munoz A., Avilés J. M.
Spatial distribution of a Tree Pipit Anthus trivialis population from Lagiewnicki Forest (Lodz – Central Poland)
Nowakowski J. J.Abstract Read Article Download21 69
Spatial distribution of a population the Tree Pipit Anthus trivialis in Lagiewnicki Forest, a wooded area close to Lodz city interested by increasing urbanization was studied. Nearest neighbour distances, population density, “mean crowding” and distribution of territories in relation to the edge of forest were analysed. Population density at the town edge was four titnes lower than that at cultivated fields edge. Frequency distribution of square roots of the nearest neighbour distances was positively and significantly skewed (a3 = 0.81), suggesting a clumped distribution. The centres of singing males territories of were on average 260 m apart. The distances between the territories and the forest edge bordering cultivated fields were positively skewed (a3 = 0.85), whilst the distances between territories and the town edge were significantly and negatively skewed (a3 = 0.42).
Note sul cleptoparassitismo dello Storno Sturnus vulgaris in periodo riproduttivo
Trotta M.Abstract Read Article Download21 44
During a study on the diet of Starling Sturnus vulgaris, several cases of kleptoparasitism, both intraspecific and interspecific, were observed. Information was collected on the techniques and frequency of success, as well as on the taxa of the stolen prey. In the case of intraspecific kleptoparasitism a technique of “threat” was applied which had low energy cost but produced a rather low percentage of success (10,9%). The fact that the prey was given up without any further aggression could be due to the possible existence of a hierarchy within the colony, containing dominant members who have priority over the young and lower ranks. In interspecific kleptoparasitism, which occurred only against Blackbird Turdus merula, the percentage of success was 84%. This was much higher than that recorded by Källander (1988) on Lapwing Vanellus vanellus which unlike Blackbird, used a variety of strategies to escape the attack of the Starling, sometimes crowned with success. In interspecific kleptoparasitism, techniques of “attack” and “chase” were used. The high energy cost incurred by the Starling was compensated by the high percentage of success gained using these two techniques (91,3%) and by the protein value of the stolen prey: 76,2% being earthworms. During the rearing of the young, catching of earthworms was carried out exclusively by kleptoparasitising Blackbirds.
- Column - Uccelli acquatici nidificanti: 1999
- Column - Book Reviews