Relocated, range-limited, but resilient: niche shift and constraints on spread in introduced Nanday parakeets (Aratinga nenday)

Introduced species often encounter novel environments that test their capacity for ecological flexibility and adaptation. We investigated ecological niche dynamics in Nanday Parakeets (Aratinga nenday), a naturalized parrot species in Los Angeles, to assess whether their introduced range reflects a shift from their native range in South America. Using principal components analysis and niche overlap tests, we found that the introduced population occupies a distinct environmental space—cooler, drier, and with less tree cover—with no measurable niche overlap. Habitat suitability modeling in Los Angeles suggests that their current habitat is narrowly concentrated in south-facing coastal canyons and not in more arid inland or high-elevation areas. Data from iNaturalist show that Nanday Parakeets roost and feed mainly in sycamore trees. The 2025 Palisades Fire impacted only 3% of suitable habitat, while the 2018 Woolsey Fire impacted 12%, neither with an observable effect on the population. Our results highlight the contradiction apparent in many species introductions: niche flexibility during establishment combined with ecological constraints on later spread.