Invasion dynamics of the European Collared-Dove are explained by combined effects of habitat and climate

Global biodiversity is increasingly threatened by the spread of invasive species. Understanding the mechanisms influencing the initial colonization and persistence of invaders is therefore needed if conservation actions are to prevent new invasions or strive to slow their spread. The Eurasian collared-dove (Streptopelia decaocto, EUCO) is one of the most successful avian invasive species in North America; however, to our knowledge, no study has simultaneously examined the role that climate-matching, human activity, directional propagation, and local density have in this invasion process. Our research expands upon a cellular-automata-based hierarchical model developed to assess directional invasion dynamics to further quantify the impacts of climate, elevation, and land cover type on the spread of EUCO in North America. Our results suggest that EUCO’s dispersal patterns can largely be explained by the effects of habitat, climate, and environmental conditions at different stages of the invasion process rather than some innate preferred north-westerly spread. Specifically, EUCO initially colonized warm and wet grassland habitats and tended to persist in urban areas. We also found that while EUCO were more likely to spread to the northeast of existing habitats, directional preference did not drive persistence and recolonization events. These findings highlight the importance of incorporating both neighbourhood effects and environmental factors in the modelling of range-expanding species, adding to the toolset available to researchers to model invasive species spread. Further, our research demonstrates that historical records of invasive species occurrences from citizen science projects can provide the data resources needed to disentangle the characteristics driving species invasion and enable predictions that are of critical importance to resource managers.

Methods
Dataset Collection:

The primary dataset in this study consists of detection records of Eurasian collared doves (Streptopelia decaocto) spanning from 1988 to 2021 in North America. These records were sourced from the Project FeederWatch database. Accompanying these records are the total number of bird count surveys conducted over this period, enriched with geographic and environmental descriptors of each location.     

Processing and Gridding:     

Temporal Grouping: The detection records were grouped into annual recordings.  

Spatial Gridding: Detection records were aligned using the grid cell structure adopted by the Christmas Bird Count (CBC).   

Filtering: We filtered out grid cells that had no surveys, and cells that were predominantly water-covered (> 50% of their area).     

Environmental Descriptors:     

Climate Data: Average temperature and precipitation data were integrated from ScienceBase North America Climate data (1950–2000).  

Elevation: Elevation data was sourced from ScienceBase North America Elevation data.  

Land Cover: Land cover descriptors, which included forest, shrub, crop, urban, and other land cover types, were integrated using the North American Land Change Monitoring System (NALCMS) land cover map from 2015.