North American Monarch

A small family of tropical or subtropical butterflies with only a few members like the milkweed or monarch species. Their wingspan extends to 7-10 cm, and their annual mass migration is spectacular the North American Monarch butterflies (Danaus plexippus) fly in autumn from southern Canada as far south as Mexico and Florida. 

IRMS has been used as a tool for studying the origin and migratory behavior of various animals, including the North American monarch butterfly [64], bowhead (baleen) whales [65], and birds [66,67]. Muccio and Jackson [11] provide a useful overview of the appUca-tion of IRMS techniques for determining the movement of animals including cattle, elephants, and wild birds. 

Estimates of these duree exposure factors and the estimated contribution of each state and province to approximately 50% of the eastern North American monarch population arising m the portion of the Com Belt, as indicated by Wassenaar and Hobson (27), provides a broad view of potential exposure (Table 1). Our estimates of overlap of the pollen-shed period in each location with the presence of monarch larvae are based partly on the projections of the simulation model described previously and partly on our own observations. In diis instance, our estimate for the exposure of monarchs in the Com Belt states and Ontario is 1.6%. Since monarchs in the Com Belt represents 50% of the total monarch population, the exposure for the entire monarch population would be 0.8%. 

Brower, J. V. Z. (1958) Experimental studies of mimicry in some North American butterflies. Part I. The monarch, Danaus plexippus, and viceroy, Limenitis archippus archippus. Evolution, 12, 32-47. 

Milkweeds exist in cornfields across most of the North American corn-growing regions and monarch butterflies utilize this resource as a host for their... 

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