Natale Emilio Baldaccini

Occurrence of a pyrazine binding protein in the nasal mucosa of some vertebrates

The presence of an olfactory protein, specific for 2-isobutyl-3-methoxypyrazine, identified in cow olfactory mucosa, has been investigated in several species of all classes of vertebrates. The methods involved measurement of specific binding with the radioactive ligand and some competitors, as well as SDS electrophoresis on the crude homogenate. The results show that such protein is present only in some families of mammals, with no clear relationship to systematic position or to natural diet. The data suggest the use of more suitable species for in vivo and in vitro studies on the function of this protein.

On the use of pharmacological sterilisation to control feral pigeon populations.

The use of chemosterilisation for controlling feral pigeon populations was investigated by: (1) quantifying the reproductive activity of pigeons in two Italian cities; (2) testing the efficacy of nicarbazin, an anticoccidial drug with rapid and reversible effects on the reproduction of laying hens, on groups of paired pigeons maintained in open aviaries; and (3) simulating the effects of the use of nicarbazin on a hypothetical population, allowing for the reproductive productivity recorded in (1) and the efficacy of this drug as obtained in (2). Breeding attempts were recorded all year round in both study sites with a minimum peak in September-October, a maximum in March-July, but with active nests in winter too. In terms of the sterility activity of the drug, the results showed only a partial inhibition of reproduction of pigeons fed ∼38-82 mg nicarbazin day −1 (kg bodyweight) −1 (500 and 800 ppm in feed), which, according to the simulations, would produce only a fleeting reduction of their abundance in the field. Data do not seem to support the use of this drug as an effective control method for feral pigeons, and they cast doubts on the opportunity to make use of chemosterilants, which produce only partial and reversible effects. The use of this drug could perhaps be considered only as part of an integrated pest-management program, which necessarily has to include the reduction of carrying capacity of the urban environment.

Foraging flights of wild rock doves (Columba l. livia): a spatio‐temporal analysis

Abstract The first spatio‐temporal analysis of foraging flights of wild rock doves is here reported. Birds living in one of the last relatively pure demes of wild Columba livia in the Mediterranean region (Capo Caccia, NW Sardinia) were observed on their foraging routes and in the course of daily movements to and from the colonial site. Foraging sites were located by systematic searches of colour‐marked birds in the study area. The pigeons followed rather stable routes in reaching foraging sites, which are mainly located in agricultural fields up to around 19 km from the colonial site. In autumn, doves tended to reduce the extent of foraging flights, feeding almost exclusively on lenti‐scus fruits located near the colony. Foraging flights in spring and summer differed from those in autumn and winter in the patterns of daily activity, the number of birds moving, and the sizes of the flocks. The possible relationships between the spatio‐temporal characteristics of foraging flights and other aspects of the biology of rock doves, especially in the breeding season, are discussed.

A long term study on initial orientation in sand martins (Riparia riparia)

Over a period of 18 years sand martins (Riparia riparia) were displaced from their breeding colonies and released to investigate the relationship between distance of displacement and initial orientation. The results show significant homeward orientation at the shortest distances of displacement (7.1-18.2 km, series A), but not over longer distances (49-180 km, series B and C). Birds displaced over 49 km from their breeding colonies only seldom show homeward directedness, while pseudo-pooling and second order analysis of their directional choices seem to indicate the tendency to fly in a given compass direction. Possible causal factors that can induce this behaviour in sand martins are discussed, taking into account not only local biasing factors but also the existence of a so called preferred compass direction. These data show that sand martins are able to determine the correct homing direction inside a probably familiar area. The response over longer distances indicates difficulties in determining the appropriate homing course at takeoff.

The possible functions of calls organization in the bittern (Botaurus stellaris)

Abstract During the reproductive period, male bitterns produce repetitive trains of signals (booms) with not yet fully understood significance for their territorial and sexual behaviour. To look for possible functions of these calls in terms of the ‘Honest Advertisement Hypothesis’ or ‘Locatability Hypothesis’, different characteristics and parameters of the vocalizations were analysed and the following evidence was obtained: (1) the number of booms per boom train, as well as the percentage of faint ‘poor’ booms, produced by 12 individuals proved to be uncorrelated with their body size or condition. (2) The highly individual variable parameters of 22 males’ vocalizations were often weakly inter‐correlated and a common organization pattern of the boom train was not recognisable. However, main element duration tended to decrease as the percentage of poor booms and the number of booms per boom train increased. (3) Boom trains of bitterns mixing full and poor booms, were characterised by main elements of variable duration uttered at regular intervals, while, for the other individuals, main elements of similar duration were uttered at longer intervals in the final part of the boom train. Furthermore on the basis of morphological modifications of the neck evaluated in 12 individuals, some considerations on the mechanism of sound production were made. The boom trains organizations did not fully match the expectations of the Honest Advertisement Hypothesis and of the Locatability Hypothesis. Bitterns appeared, in fact, to look for a trade off between boom train length and main element duration: longer boom trains made up mainly of poor booms may be due to the need to prolong the trains, reducing the duration of the main elements (which would then be poor) or to that of prolonging trains formed by shorter casually produced poor booms.

Density and habitat requirements of red-legged partridge on Elba Island (Tuscan Archipelago, Italy)

Abstract The red-legged partridge (Alectoris rufa, Linnaeus 1758, Phasianidae) is a common game bird in Europe and it is classified as SPEC 2 (Species of European Conservation Concern), that is, a species with unfavorable conservation status due to a marked population decline. Loss of suitable habitat and hunting management are considered among the major causes of its decline. Such a decline can be also related to agriculture intensification, changes in agricultural practices and the abandonment of less productive lands. Habitat suitability models are an important management tool to define the potential distribution range of a given species, design a protected area network, and plan appropriate management actions and evaluate their effects. This study was conducted on Elba Island (Tuscany) in spring 2011 to define the habitat factors that affect the A. rufa distribution in a typical Mediterranean landscape. On this island the species is declining, as it is in other areas of Europe. We carried out point counts in a survey stratified according to vegetation. We formulated Resource Probability Selection Functions following a presence vs. availability design by Binary Logistic Regression Analysis to obtain a map of potential distribution of the species. We observed that the red-legged partridge distribution was mainly linked to the natural habitat with garrigue and perennial meadows, whereas woody landscape had a negative effect. To stop the species decline on the island habitat improvement actions are needed, such as the cutting of dense vegetation to create open areas.

Consistency and overlap of the diet of seven passerine trans-saharian migrants during spring stopover at two mediterranean sites

Abstract The diet of seven passerine trans‐saharian migrant species was analysed by means of faecal analysis during their spring passage at an Italian stopover site (Sardinia). Here birds co‐occur at high densities in a mostly unknown and unpredictable environment. This allows us to analyse the consistency of the species’ feeding pattern in different weather conditions (Capo Caccia 1990–1991) and sites (S. Pietro 1992). The diets of the seven species are mainly composed of insects, they are consistent over the three study years and they reflect the birds’ foraging behaviour. The pied flycatcher and the redstart (mostly ants), the garden warbler and whitethroat (varied diets including Formicidae, Coleoptera, Apbidoidea, berries), and the willow and the wood warblers (mostly Apbidoidea) are similar or closely related, and form three species pairs with very similar diets. The spotted flycatcher is similar to the first pair, but with a higher proportion of Diptera and Hymenoptera (non Formicidae). Since speci...

The dusk orientation and the influence of successive tests on Pied Flycatchers (Ficedula hypoleuca) tested in Emlen funnels

Abstract Pied flycatchers were tested twice at sunset under a clear sky, a clear sky with moon, and under artificial overcast conditions. The mean spring direction was W‐NW, with a higher westward bias than in previous tests performed in complete darkness. The activity of single tests was high but their directionality was low, with an inverse correlation between activity and directionality. Under clear skies (with or without moon) the distribution of birds performing a test for the first or second time was not different, with high consistency of individual birds, while in overcast conditions second tests shifted southwards, seemingly a phototactic reaction. Under clear skies (with and without moon), in the second test individual vector lengths increased and there was no correlation between individual activity and vector value, indicating an improvement of the perform ance; in contrast, in second overcast tests vectors tended to decrease and the negative correlation activity/vector was significant. So, alt...

Multilocus approach reveals an incipient differentiation process in the Stone-curlew, Burhinus oedicnemus around the Mediterranean basin

The Stone-curlew Burhinus oedicnemus, a steppe bird species, is mainly distributed in the Mediterranean and Macaronesian regions, which are considered hotspots of biodiversity with priority for animal and plant species richness conservation. In this study, we investigated the genetic diversity of the Stone-curlew in the Mediterranean basin and in the Canary Islands by applying a multilocus approach. We analysed mitochondrial and nuclear markers in order to evaluate the genetic structure and the congruence between morphological subspecies and geographic samples. We found a significant level of genetic differentiation between Mediterranean and Canary Island populations with all markers. Both in the Mediterranean basin and in the Canary Islands, we found a significant level of genetic diversity with nuclear markers only. We identified seven population groups, including insular populations. The four subspecies described for the Western Palaearctic were confirmed with some changes in distribution range. In spite of habitat fragmentation and negative population trend, the Stone-curlew showed a significant level of genetic diversity and gene flow among continental populations. However, islands constitute important reservoirs of genetic diversity and a potential for the evolution of the species.

On the interplay between phylogeny and environment on behaviour of two urban bird species, Columba livia and Corvus corone (Aves)

Abstract Different hypotheses exist to explain the ability of individuals or species to modify their behaviours in response to the urban environment. Our study addresses risk-taking in urban birds as an essential behavioural change in cities allowing the species to manage living in anthropic habitats. Specifically, we tested role of phylogeny and the environment on risk-taking, expressed in lower escape distances. We adopted a comparative approach and compared the flight distance of urban pigeons and urban crows in Paris with rural wild rock doves and crows in Sardinia, thus contrasting environmental conditions (urban or rural), species (columbids vs. corvids) and type (feral or wild). Pigeons had lower flight distance than crows in both rural and urban environments, and rural individuals of both species had higher flight distance than urban individuals. However, this intraspecific difference was higher in pigeons than in crows, and the interspecific difference was higher in urban than in rural areas. Our study shows that risk-taking in birds is the outcome of a complex interplay between several environmental and phylogenetic factors, and confirms the hypothesis of increased risk-taking in urban pigeons as a result of a pre-adaptation due to artificial selection, as often suggested but never scientifically demonstrated.