Restoring Food Chains for Monarch Butterflies in the Southwestern United States

Abstract

The migratory phenomenon of monarch butterflies has many threats to its continued existence. To promote the restoration of monarch butterfly floral corridors and food chains in the desert southwestern United States, this study examined the distribution of 50 important nectar and larval host plants known to support monarch butterflies. Using Maximum Entropy (MaxEnt) to model each individual species’ distribution, the study examined the distribution of monarch butterfly plants individually and collectively for cues toward better understanding of potential monarch movement in the desert southwest. The study proposes strategies for protected area management to benefit pollinators and monarchs, as well as for the distribution of monarch food plants at two different geographical scales and throughout the annual yearly cycle of flowering. The results of this study indicate that stacked species distribution models are successful at explaining the presence of monarch butterflies better than a random sample. However, the precision of any predictive value of these findings is limited due to the overall coarseness of the models. The results indicate modeled phenological predictions are generally accurate and overall provide a visualization tool to promote better understanding of the timing and availability of monarch butterfly floristic habitat in the desert southwest. The results suggest an appropriate response for public land managers is to work at increasing the availability of local native plant materials. Whether in the form of wild harvesting or agronomic production, greater availability of locally-sourced native plant materials has the potential to surmount many existing impediments to successful restoration of monarch butterfly populations.