Abstract
Abstract The spread and distribution of exotic species depends on a number of factors, both anthropogenic and biophysical. The importance of each factor may vary geographically, making it difficult to predict where a species will spread. In this paper, we examine the factors that influence the distribution of monk parakeets (Myiopsitta monachus), a parrot native to South America that has become established in the United States. We use monk parakeet observations gathered from citizen-science datasets to inform a series of random forest models that examine the relative importance of biophysical and anthropogenic variables in different regions of the United States. We find that while the distribution of monk parakeets in the southern US is best explained by biophysical variables such as January dew point temperature and forest cover, the distribution of monk parakeets in the northern US appears to be limited to urban environments. Our results suggest that monk parakeets are unlikely to spread outside of urban environments in the northern United States, as they are not adapted to the climatic conditions in that region. We extend the notion of “substitutable habitats,” previously applied to different habitats in the same landscape, to exotic species in novel landscapes (e.g., cities). These novel landscapes provide resources and environmental conditions that, although very different from the species’ native habitat, still enable them to become established. Our results highlight the importance of understanding the regionally-specific factors that allow an exotic species to become established, which is key to predicting their expansion beyond areas of introduction.
Highlights
The distribution of an exotic species is the outcome of complex interactions between the species’ biology, the environment into which the species is introduced, and anthropogenic disturbances that create novel ecological opportunities (Thuiller et al 2006)
We examine the factors that influence the distribution of monk parakeets (Myiopsitta monachus), a parrot native to South America that has become established in the United States
We found that a different set of variables explained the distribution of monk parakeets in the southern and northern United States (Fig. 2)
Summary
The distribution of an exotic species is the outcome of complex interactions between the species’ biology, the environment into which the species is introduced, and anthropogenic disturbances that create novel ecological opportunities (Thuiller et al 2006). Because urban landscapes provide such ecological opportunities and are often the point of introduction for new species, many exotic species thrive in cities (McKinney 2006). If environmental conditions in an area are unsuitable for a species, the probability of its establishment at that location is low. Even in suitable environmental conditions, a species introduction may not lead to a viable population due to stochastic die-off events (Simberloff 2009). The temporal and spatial patterns of propagule pressure are thought to play an important role in establishment success (Catford et al 2009; Chiron et al 2009; Simberloff 2009). Greater propagule pressure increases the chance of a successful invasion by increasing genetic diversity and continually supplementing the population (Colautti et al 2006)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
