ABSTRACT. One of the most successful avian urban invaders is the House Sparrow (Passer domesticus). Here, we examine House Sparrow numbers in the urban-agricultural landscape of three cities, one where the sparrow is native (Barcelona) and two where it is nonnative (Los Angeles, Mexico City), comparing between five different land classes based on land-use, location relative to urban center, and urbanization intensity. We estimated sparrow densities using distance-sampling corrected procedures and compared sparrow numbers between the three cities and between the land classes within each city. This two-year survey showed the highest density of sparrows occurring in Mexico City and the lowest in Los Angeles. In both cities where the sparrow is nonnative, we recorded the greatest abundances in highly urbanized areas. In Barcelona, where the sparrow is native, abundances did not differ among land classes. We also related sparrow numbers to specific environmental variables, describing vegetation structure, urban infrastructure, and human activity, using classification and regression trees. We found several variables related to differences in House Sparrow abundances among the three cities. For Los Angeles and Mexico City, the most important variables explaining House Sparrow numbers were urban infrastructure (i.e., maximum building height, high urbanization) and/or human activity (i.e., pedestrians), all of which related positively with sparrow abundance. For Barcelona, sparrow numbers showed both positive and negative relationships with vegetation (i.e., tree abundance, maximum tree height, maximum herbaceous plant height) and human-related variables (i.e., cars, pedestrians). Although the scope of this study is geographically limited to three cities, our results suggest that House Sparrow numbers between cities and land classes areas vary considerably, and are likely determined by a complex array of variables. Our study provides some insight to the growth and decline of House Sparrow populations in their nonnative and native ranges, respectively. Alerte aux envahisseurs: Densités de moineaux domestiques au long de trois paysages agrico-urbainsRÉSUMÉ. Un des envahisseurs aviaires ayant le plus de succès est le Moineau Domestique (Passer domesticus). Ici, nous examinons les densités dans les zones agrico-urbaines de trois villes, une où le moineau est natif (Barcelone) et deux où l'espèce est considérée envahissante (Los Angeles, Mexico), en comparant entre cinq classifications terrestres établit selon l'utilisation du territoire, localisation relative au centre urbain, et l'intensité d'urbanisation. Nous avons estimé les densités de moineaux en utilisant la méthode d'échantillonnage selon la distance corrigée et avons comparé le nombre de moineau entre les trois villes, ainsi qu'entre les classifications terrestres dans chaque ville. Cet échantillonnage de deux ans a démontré la plus grande densité à Mexico et la plus basse à Los Angeles. Chez les deux villes où le moineau est considéré comme envahissant, les densité...