Population size of the Monk Parakeet Myiopsitta monachus in Catalonia

The Monk Parakeet Myiopsitta monachus was first recorded in Barcelona city in 1974, and by 1994 its population had grown to 850 individuals. The aim of the work reported herein was to produce an updated estimate of its current population size both in Barcelona city and in Catalonia, as this information is essential for predicting the spread of this invasive species in the near future. Post-reproductive population size was estimated indirectly during September and October 2001, by counting the total number of nests and chambers present, and estimating the mean number of individuals roosting per chamber (n = 129 chambers). Given totals of 313 nests in Barcelona and 492 in Catalonia, and an occupancy rate of 1.52 (SD = 1.80) birds per chamber, we estimated the Monk Parakeet population in Barcelona city at 1,441±265 individuals and that of Catalonia at 2,199±392 individuals. In Barcelona the detected population growth fits an exponential model, with a current population-doubling time of approximately nine years. From a direct inspection of 146 chambers for breeding activity, we estimated the number of breeding pairs in Catalonia in 2001 at 610-650 pairs, of which 402 were in Barcelona. The Monk Parakeet population has shown a marked range expansion in Barcelona and substantial population growth in several areas around the city. The species has also expanded its range all around Catalonia, and has already colonized important crop-growing areas. This could point towards possible problems in the future, and the advisability of active management of the species before too long.

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