Ecology of the Monarch Butterfly
North America forms the core of the monarch’s distribution but the overall range extends through Central America and the Caribbean to South America. Monarchs also occur in Hawaii, Australia, and several Pacific islands, as well as parts of Asia, Africa, and southern Europe (Zhan et al. 2014). Several populations outside of the Americas appear to be nonnative, originating from introductions that are thought to have occurred in the 1800s (Vane-Wright 1993), but Zhan et al. (2014) suggests that introductions may have occurred much earlier. Although the precise population size of many island and non-American populations is unknown, native North American monarchs probably represent the vast majority of the total global population.
The North American migratory population is genetically distinct from non migratory monarch populations (Zhan et al. 2014). While small-scale movements and winter roosting have been noted in Australia, only the North American populations are known to be strongly migratory.