2-Isobutyl-3-methoxypyrazine, a potent bell-pepper odorant, binds to cow olfactory mucosa homogenate. The receptor is saturable in the micromolar range and is competitively inhibited by other bell-pepper odourants, but not by other pyrazines of different odours. Other tissues do not bind 2-isobutyl-3-methoxypyrazine at a significant extent. We suggest that this receptor is involved in odour discrimination.

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.

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 lentiscus 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.KEY WORDS: Rock dove -Columba l. livia -Foraging flightsActivity pattern. ACKNOWLEDGEMENTS

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a viable and efficient alternative to the traditional methods used to estimate feral pigeons 31 population size and to monitor trends.

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Foraging flights of feral pigeon populations may differ in occurrence and extent from town to town. In this paper, the annual pattern of such flights from three medium-sized Italian cities (Venice, Parma and Lucca) is described and compared with that recorded for a Mediterranean population of wild rock doves from Sardinia. The data provide evidence of the similarity of these flights both within urban populations and between feral pigeons and wild rock doves. On the other hand, the presented results point to a noticeable flexibility of this behaviour, whose features seem finely adapted to the environmental features of an urban habitat and its surroundings. In particular, the distribution of food resources and of the annual trend of reproductive attempts appear to exert a leading role in shaping the characteristics of these flights.