Population viability analysis of monk parakeets in the United States and examination of alternative management strategies

In the United States, monk parakeets (Myiopsitta monachus) are expanding their geographical distribution, and their overall population size is growing exponentially. Monk parakeets are causing widespread economic damage in the United States by nesting on utility structures, which leads to electrical fi res and power outages. Although few life history data are available for the species from North America, extensive data are available from the species' native range in South America. Incorporating data from South America into the population viability analysis program VORTEX, we simulated population growth in United States monk parakeets to determine whether it is likely that the United States population shows life history patterns similar to those in the native range. The answer was, no. The intrinsic rate of growth (r) of monk parakeets in the United States (r = 0.119 during the period 1976-2003) was almost double the rate of population growth (r = 0.064) for the simulated population. Modifying the South American data to allow for reduced mortality, higher fecundity, or a greater proportion of breeding females resulted in population growth rates similar to those in the United States. We extended the simulations to examine the effectiveness of alternative control measures on the monk parakeet population by using the modifi ed life history data. Simulations revealed that it would be necessary to remove 20% of the adult population or to destroy 50% of the nests each year to reduce the population size of monk parakeets. In practical terms, such massive management efforts are unlikely to be sustainable. Instead, control of monk parakeets will likely require an integrated approach including removal of local problem nests on a case-by-case basis and long-term population reduction through trapping or chemical sterilization.