Naturalized species may be a leading threat to global biodiversity, but this contention has been hotly debated. The largest global driver of invasive species management is the Convention on Biological Diversity which called on member nations to identify priority invasive species and control or eradicate them by 2020. About 50 parrot species (15% of all species) have naturalized populations. Two species are particularly successful with over 40 populations each: Rose-ringed and Monk Parakeets. Much has been written about their negative ecological and economic impacts, and in response to their success, they have been repeatedly labeled priority invasives and targeted for control. However, our literature review suggests that few impacts have been quantified by scientific study and nearly all naturalized parrot populations have no or low-level impacts. We could find only two cases where naturalized parrots were having population level impacts on other species: Rose-ringed Parakeets displace greater noctule bats in Sevilla, Spain and slightly suppress periurban nuthatch populations in Western Europe. By comparison, the IUCN Red List shows that 1,312 species of birds and mammals are threatened by non-native invasive species, and our work suggests only two (0.15%) are being impacted by parrots. Economic impacts of naturalized parrots in the US and Europe are similarly small: naturalized parrots cause < 0.005% of the total damage caused by all invasive species combined. Given the very small relative ecological and economic impacts, we feel it is difficult to label naturalized parrots as Priority Invasive Species.

The use of foster parents in avian population management is a technique with great potential to aid in the recovery of highly endangered species. However, few studies have investigated how to accomplish this successfully. Our research shows that Scarlet Macaws in southeastern Peru hatch 2-4 chicks per nest but just 1.4 fledge. Here about 24% of all hatched chicks die of starvation and starvation is the most common cause of chick death. Parents always raise the first chick that hatches, but 27 % of second chicks, 81% all of third and 100% of all fourth chicks are left to starve to death by their parents. Our goal was to develop and test new techniques to increase survival of wild Scarlet Macaw chicks by reducing chick starvation. We hypothesized that we could pull chicks at risk of starvation, raise them in captivity to about 18 days of age then move them to nests with only one chick to increase their chances of survival. Our results show that all relocated macaw chicks were successfully accepted by their foster parents (N=28 chicks, 3 consecutive breeding seasons) and 89% of the translocated chicks fledged successfully. Overall, we increased fledging success per available nest from 17% (1999 -- 2016 average) to 25% (2017 to 2019) and decreased chick death by starvation from 19% to 4%. These findings show that the use of foster parents in the wild is a promising management tool to aid wild parrot population recovery in areas with low reproductive success.