Resumen de Censo de palomas (Columba livia var.) de la ciudad de Barcelona: Aplicación del muestreo estratificado con factor de corrección
Success in the managernent of natural populations largely depends on the precision and accuracy of population size estimations. The number of Feral Pigeons in Barcelona city (NE Spain) was first estimated in 1983 by Uribe et al. (1984). In order to inprove that estirnotion, we carried out a second census of pigeons at the end of 1990 including correction factors, based on the detectability of the soecies. And stratified sarnolina. The cib was divided into 200 u squares; and a random subsarnple of 64 were sun/eyed, following Uribe et al. (1984). Visual sampling (28 transects) of marked birds (N=50 marked birds frorn which 44 were subsequently observed) showed that in any single survey only a mean of 12, 18 (S. E. =O. 87) were recorded. This means that, in any single census, 72% of the population is not visible. Therefore we suggest multiplying the results of the census by a factor of 3.5 (44/12=3.66). The final density was estimated as of 2849 individuals per Km2. The distribution of birds in Barcelona is shown. Highest densities appear in the centresouth of the city (strata I and 11, Fig. I), with a lower density around this area (stratum V), and intermediate densities in the eastern and western parts.
